# PM-1236 motor issue



## tino_ale (Oct 22, 2014)

Hi guys,

I'm still in the process of properly setting up my PM-1236 but I suspect I have something wrong with my motor.

I noticed the machine would run quite loud and has some strong vibrations. I machined a titanium bead that came out as you see below : huge pattern is transfered to the finish.







I proceeded to check the spindle bearing preload :
- I did the "one finger spin" test, I get about 1 turn of free spining, that's supposed to be right. The chuck is not that free to spin.
- I chucked a 40mm rod in the 3-jaw chuck, grabbed with both hands that bar 400mm away from the chuck. DI positionned above the centerline, tip on the spindle cam lock area. Vertically I get about 0.0003" in the down direction; a little less around 0.0002 up. That makes sense, as it is easier for me tu push down than pull up. So 0.0005" overall. Not sure how much is acceptable but doesn't sound that much.

So I rulled out a sloppy spindle.

I then removed the belts and ran the motor alone. Left the sheave on. This is what I found :
- the noise and vibration is mostly still here, so the issue is narrowed at the motor+sheave level
- by hand, it is very easy to turn, no noticeable grit feeling, smooth (but not entirely silent ?? maybe normal, I speculate I hear the balls running in the bearing)
- *when powered on, the loud humming is back along with the vibration*
- I feel vibration on the motor body itself. The lathe yes but not that much. The stand, a lot. The stand acts like a resonator of some kind.
- *as soon as I stop the motor power, the humming and the vibration stops eventhough it is still spinning fast*. Then the motor continue to turn freely, for about 5-10 seconds. During that time, I only hear what I think is the bearings running, but the machine is silent otherwise and vibration free.

conclusion : the issue is at the motor level and only there when the motor is powered on. That pretty much rules out a defective bearing or an imbalanced rotor.

Here is a video of the sound.

Did any of you have had that kind of issue ? What is the fix ? I have a metric machine in 220V, could it be related ?
I speculate the issue is electrical but I do not know that for a fact.

Any advise welcome !
Thanks !


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## JimDawson (Oct 22, 2014)

I think you have found the problem, but I can't tell you exactly what is causing it.  Based on your excellent troubleshooting, it must be electrical and internal to the motor.

The only fix I can think of is to replace the motor, or isolate the motor with rubber mounts.


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## tino_ale (Oct 22, 2014)

Thank you.

Actually another PM1236 owner has heard my video and says the free spinning sound (right after I shut the motor power off) doesn't sound normal to him.
If you hear close enough, there is a noise even in the free spinning phase indeed.

So it seems I may have ruled out the motor bearing and/or balance a little too fast.

Anyhow, I cannot run the lathe with so much vibration from the motor. It is a brand new machine, I'd rather have a normally running motor than a lemon mounted on rubber pads.

There's another thing : I wonder if the motor is not running too hot. When I did the break-in procedure, the 3 jaw chuck was on but empty. I ran the lathe for 5 min on each speed, forward and reverse. So it took a while. I then noticed the shop was getting warmer, I touched the motor and almost burned myself. Pulled an IR thermometer, found the motor body was 90°C (almost 200°F). That sounds really hot for a machine that is running with no actual cutting load. Oil levels are spot on and oil type is good. I don't know what is going on.

I have enquired Matt about that motor issue and waiting on his reply.

Any thoughts are welcome


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## coolidge (Oct 22, 2014)

Yes, given the 200 degree temp unplug it before something melts and you get an electrical zap. Water boils at 212 degrees.


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## Morgan RedHawk (Oct 22, 2014)

You probably already thought of this, but aren't yall on 220v 50 Hz?  Is it a 60 Hz motor?  Don't know if it would make a difference or not, just a thought.  The bead looks cool with those lines in it, though!


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## JimDawson (Oct 22, 2014)

90C does seem way to hot.  I wonder if the motor has a dead winding?  Bad run capacitor?  Bad (sticking) centrifugal switch?


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## gregg (Oct 22, 2014)

Always told if you cannot lay your hand on it its to hot. Some times cannot lay your hand there on motor very long but can lay your hand on it . Should be a temp rise for the motor above the room temp? Bottom line you need new motor.


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## GA Gyro (Oct 22, 2014)

I agree... there is something wrong with the motor.  

The hum sounds like an electrical issue... as thought the motor is fighting with itself.  And the temp is WAAAY too hot, even if you were dogging the lathe doing cuts too deep.  
Might try running the motor (with the belt removed) for about 1/2 hour continuously... then take its temp again.  A motor running with NO load, should not heat up at all... that would be a significant clue. 

Not sure if you have any motor shops in your area... we have them around me and they could tell if I took the motor to them... or you Emailed them the video.
Might find a motor forum and post the video to see what you get back.

Contact Matt... he has always been straight with me.  

And let us know what you find.

THX

GA


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## mksj (Oct 23, 2014)

As mentioned, most of the EU is 230v 50 Hz. This will cause the motor speed to be less and in some cases some motor derating, but unlikely to be the cause of the issues mentioned. Although it sounds like a replacement motor would be appropriate as opposed to repair,, changing to a 3 phase inverter motor with a VFD would probably be a better option. This would afford you a wider speed range and better surface finish.


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## John Hasler (Oct 23, 2014)

Doesn't sound right.  I'd say you have a stuck centrifugal switch, but I think I hear it operating when you turn the motor off and it spins down.   Have you made sure it's wired correctly?


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## tino_ale (Oct 23, 2014)

Hi guys,

Thanks for all the feedback.



> Might try running the motor (with the belt removed) for about 1/2 hour continuously... then take its temp again. A motor running with NO load, should not heat up at all... that would be a significant clue.


I'm going to try that good idea.



> Not sure if you have any motor shops in your area... we have them around me and they could tell if I took the motor to them... or you Emailed them the video.


Unfortunately no, there are no small shops around here anymore.



> You probably already thought of this, but aren't yall on 220v 50 Hz? Is it a 60 Hz motor? Don't know if it would make a difference or not, just a thought. The bead looks cool with those lines in it, though!


During the ordering process Matt told me 50/60Hz would be fine, and I don't think it would mess up with the motor like that. I'm not an expert though.
Yeah the finish really came out funky. Funny thing is, with a smooth running machine, I would be absolutely clueless if someone asked me to make another one like that.



> Doesn't sound right. I'd say you have a stuck centrifugal switch, but I think I hear it operating when you turn the motor off and it spins down. Have you made sure it's wired correctly?


I also think I hear it operate at the end of the free spinning.
About the wiring : how could it possibily be badly wired ? There is only neutral, phase and ground right ? I don't know what kind of incorrect wiring would produce that issue 



> The hum sounds like an electrical issue... as thought the motor is fighting with itself.


I completely agree with you. At the second I shut the power off, 90% of the sound and vibrations immediately stop.


I have contacted Matt yesterday and waiting on his reply.

Will keep you posted!
thanks again


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## mksj (Oct 23, 2014)

<!--[if gte mso 9]><xml>  <w:WordDocument>   <w:View>Normal</w:View>   <w:Zoom>0</w:Zoom>   <w:TrackMoves/>   <w:TrackFormatting/>   <wunctuationKerning/>   <w:ValidateAgainstSchemas/>   <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid>   <w:IgnoreMixedContent>false</w:IgnoreMixedContent>   <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>   <woNotPromoteQF/>   <w:LidThemeOther>EN-US</w:LidThemeOther>   <w:LidThemeAsian>X-NONE</w:LidThemeAsian>   <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript>   <w:Compatibility>    <w:BreakWrappedTables/>    <w:SnapToGridInCell/>    <w:WrapTextWithPunct/>    <w:UseAsianBreakRules/>    <wontGrowAutofit/>    <w:SplitPgBreakAndParaMark/>    <wontVertAlignCellWithSp/>    <wontBreakConstrainedForcedTables/>    <wontVertAlignInTxbx/>    <w:Word11KerningPairs/>    <w:CachedColBalance/>   </w:Compatibility>   <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel>   <m:mathPr>    <m:mathFont m:val="Cambria Math"/>    <m:brkBin m:val="before"/>    <m:brkBinSub m:val="--"/>    <m:smallFrac m:val="off"/>    <m:dispDef/>    <m:lMargin m:val="0"/>    <m:rMargin m:val="0"/>    <m:defJc m:val="centerGroup"/>    <m:wrapIndent m:val="1440"/>    <m:intLim m:val="subSup"/>    <m:naryLim m:val="undOvr"/>   </m:mathPr></w:WordDocument> </xml><![endif]-->  [FONT=&quot]After some additional research, there were three points that came to light and could account for your motor issues.[/FONT]
  [FONT=&quot]A single phase 60 Hz motor can be run on 50Hz if the voltage is proportionally reduced (V/Hz ratio), so in this case you would need to run the motor on something like 190V. The motor will run 20% slower and the Hp will be derated by 20% or more. Running a 60 Hz motor at 50Hz on 230V means that during part of every power line cycle the magnetic structure of the motor will probably be overloaded.   This will cause excessive current to flow heating the motor quickly, which is what you are reporting. I have also seen this in various types of transformers in equipment, they quickly burn up.[/FONT]
  [FONT=&quot]When a 60Hz single phase motor is brought down in frequency the centrifugal start switch may not ever reach opening speed.  Given that the switch opening speed setpoint is usually set at around 80% of running speed, it may not be disengaging.  If it doesn't reach switch speed, smoke is definitely on the way!  
 [/FONT]
[FONT=&quot]Single phase motor start and run capacitor are designed for a specific frequency and voltage, when  lowering the frequency their affect is reduced, and can derate the performance of the motor. Usually incorrect sized or damaged start/run capacitors will result in motor overheating.[/FONT]

 [FONT=&quot]Check the name plate ratings on your motor.  It specifies 220V at 60Hz, then you probably need to replace the motor if you do not reduce the mains voltage. In most cases, this simplest and most cost effective solution is to replace the single phase motor with a 220-240V 50Hz model. The alternative is to go to a 3 phase motor with a VFD, which is what I did on my PM lathe.[/FONT]


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## tino_ale (Oct 23, 2014)

Ok so I checked both the Lathe ID plate and the motor plate. Both say 220V and 60Hz. Not 50Hz.

Here is the motor plate :






Those are not really reassuring news... don't know what to think!
I came home too late tonight to run the motor free of any load and recheck the temp.
I am sure about the very high temp when I broke the lathe gears in, and back then oil level was normal, oil viscosity ISO 68, nothing in the chuck and finally I have checked my spindle preload and all seem fine.

The centrifugal thing, honestly I don't even know what this is, but I think I hear it click near the end of free spinning after I shut the motor off in my video. As if it was re-engaging. It is there in the video. Not sure if it is enough to rule out that possible issue.

Let's see what Matt thinks about that motor.

What I know for a fact is that I asked about both the voltage and frequency to Matt prior to ordering and he was clear that would be no problem at all to run under 220V and 50Hz.

Now, I have not run the lathe for dozen of hours yet, but I have broken-in the gears and used it a little (to make the Ti bead and a few other parts). If I do fix it with a new cap or whatever it would be, I hope it has not suffered some permanent damage.

It also occurred to me that the rest of the lathe is 60Hz spec, I hope other electrical components will not suffer from an improper frequency supply.


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## John Hasler (Oct 23, 2014)

While that motor might not deliver a full 1.5kW on 50Hz it should idle just fine without making a lot of noise or getting hot.  Can you measure how much current it's drawing?


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## tino_ale (Oct 23, 2014)

I have one of those watt-meter that I plugged between the lathe and wall outlet.

Lathe ready, all off :
0.35A / Power factor 22

Lathe light turned on :
0.45A / Power factor 75

Motor on (no belt on) :
19.5A / Power factor 30

No do not quote those numbers, I don't understand why the power factor changes like that.
I don't know if that is normal or if the meter is fooling around.

Tried it on a light I have (40W bulb), said 0.2A / power factor 100
Then on my dyson fan :
off : 0.01A / PF 30
on : 0.2 / PF 70

Don't know if that helps. Again I have my doubts on that meter and I don't know if it can be trusted. Unfortunately I have no other mean to measure the actual current draw of the motor.


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## John Hasler (Oct 23, 2014)

The numbers for the fan and the light are as I would expect.  Something in your lathe is drawing a little bit of current when it is "off".   The numbers for the motor indicate that it is defective.  I think that your centrifugal switch is stuck or somehow bypassed so that it's in the circuit all the time: that's about how much current it would draw.  Perhaps they swapped the start and run capacitors at the factory?

I'd open that motor up and check the wiring.


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## tmarks11 (Oct 23, 2014)

tino_ale said:


> Motor on (no belt on) :19.5A / Power factor 30


:yikes:

What ever you do, don't run the thing any more until you solve the problem.  That is almost 3x the label plate current (7.3A)... it is drawing more current than a 5HP fully loaded motor.

200F? While the NEMA Class B Insulation is rated at 266F, I bet the internal temp of the motor is near or past the limit.  Any additional operation is going to kill the motor... and probably start a fire. Fire extinguisher handy?

Do you have a phototach?  Bet you the motor is NOT spinning at 1680 rpm.


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## GA Gyro (Oct 23, 2014)

tino_ale said:


> I have one of those watt-meter that I plugged between the lathe and wall outlet.
> 
> Lathe ready, all off :
> 0.35A / Power factor 22
> ...





tmarks11 said:


> :yikes:
> 
> What ever you do, don't run the thing any more until you solve the problem.  That is almost 3x the label plate current (7.3A)... it is drawing more current than a 5HP fully loaded motor.
> 
> ...



I agree, that motor is drawing WAAAAY too many amps... and will self-destruct if you continue to run it.

I would send those amp ratings to Matt in another Email... This is definitive information.

OTOH: The wavy finish looks good!


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## tino_ale (Oct 27, 2014)

Ok I got a chance to do the test I wanted and ran the motor free of any load. No belt, just the sheave on.
As before, the motor seem to run pretty free of any resistance by hand.

Started at room temperature 17°C. Used an IR temp device, at the middle of the motor body, underneath the casing (easiest access).
5 min : 35°C
10 min : 44°C
15 min : 56°C
20 min : 62°C
25 min : 69°C
30 min : 75°C
35 min : 79°C
40 min : 84°C
45 min  : 88°C

I stopped there. It was pretty obvious where this was going, somewhere north of 90°C.

Matt replied to my request. He said he was sure the 50/60Hz difference would definitely NOT explain the issue I'm having. Motor are stamped 50 or 60Hz depending on where they are going to be sold, but they are the same.

He said he wasn't sure the free load test would mean much but I ran it anyway because it's an easy and repeatable data point.
He said he's not sure about the temperature.

What I need to know is if those temperature are a hard evidence that the motor is not running normally. Would someone with a PM1236 be kind enough to try the same test ?
Not on purpose but on occasion, next time you need to change the belt setting ?

BTW, running the motor in forward or reverse doesn't make any difference at all.


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## John Hasler (Oct 27, 2014)

The current measurements you made previously suffice to conclude that the motor is defective.


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## tino_ale (Oct 27, 2014)

I needed the temp test because I don't trust the Amp meter that I have used for the current measurements. It's been showing really funny numbers some times... but now it seems both tests indicate something is wrong unfortunately.

Next investigation, looking into the wiring... duh... I wish I could just be turning parts :whiteflag:


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## GA Gyro (Oct 27, 2014)

I would look into the wiring... it is possible the motor is wired incorrectly.  

There is a junction box on the side of the motor... 

AFTER REMOVING ALL POIWER CONNECTIONS FROM THE MACHINE (UNPLUG IT); open the cover and take some pictures of both the wiring inside and the diagram that explains how to wire the wires coming from the inside of the motor... and post the pictures.  

Lets see how it is wired.

Another thought would be to obtain (borrow or buy) a clamp style amp meter, and run an amp test.  Note that when running an amp test, one must isolate ONE WIRE to the motor, clamp the meter around that ONE WIRE, and read the meter while the motor is running.  Clamping the meter around more than one wire, will result in a totally worthless reading... and of course the ground wire is not a wire to read.  

Note to turn off ALL power (unplug the machine) before fiddling with the wiring.  It would really be better if you had someone there who understands electricity and motors... as there is a HUGE potential for danger and injury messing with electricity.  Better safe than sorry... or hurt.  

Be interesting to find the amp draw with the motor free (no belt).  If it is more than 10% above the nameplate... then IMO either the wiring is wrong, or the motor is bad.  

Hope this helps.

GA


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## mksj (Oct 28, 2014)

The issue on 50 and 60 Hz single phase motors being the same, is only if they are designed so. There are motor designed as such, and also a voltage operating range. The voltage range is usually more forgiving (+/-10%, but does effect longevity). I checked Marathon Electric motors for similar single phase 2HP 4 pole motors, only 1 out of 9 was specifically stated to operate at 50 or 60 Hz, and its horsepower is derated 25%. There is enough postings on the issue to see if it is hit or miss in different situations, and quite a few where it doesn't work. Three phase motors are a different animal.  

The bottom line, there is nothing special about the single phase motor connections (i.e. two wires). There rest of the control system could care less about 50 or 60Hz supply voltage. I wouldn't waste anymore time on what is a defective or incorrectly rated motor, it happens. So either get a replacement sent, or work out a credit and get a local 50Hz replacement motor. Alternatively a three phase motor with VFD will give you a wider speed range, but you need to be comfortable with the conversion.


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## GA Gyro (Oct 28, 2014)

Just my $0.02 worth:

If I were faced with having to replace the motor... and I could find the tech support to do it... I would seriously consider the 3PH motor and VFD.  Yes, there are some wiring issues, and yes there are some software programming issues... the latter would drive me up the wall.  
HOWEVER:
IMO the results would be well worth the weeding through the issues.  

Just my thoughts.

GA


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## tino_ale (Oct 29, 2014)

OK I checked the capacitors, they look ok.

That is the wiring sticker :






And that is the actual wiring :





From the lathe electrical box to the motor :
- RED goes to U1 (brown on the motor side)
- WHITE goes to Z1 (black on the motor side)
- BLUE goes to Z2 (red on the motor side)
- BLACK goes to U2 (grey on the motor side)


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## mws (Oct 29, 2014)

If the wiring appears OK and the caps seem to be in the right places I strongly suspect that the centrifugal start switch is failing to open.  I hear the switch clicking in your video as the motor spins down, but that's no guarantee that the contacts are not fused shut.  If that's the case it should be an easy fix to pry them apart and burnish with a small file.  It's not uncommon for start windings two burn these contacts, although they usually char and fail to close.  Either way, that's my first suspicion and I'm sticking to it.


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## mikey553 (Oct 29, 2014)

I can believe the factory uses the same motor for 50 and 60 Hz with 220 V service. I had a similar problem with the motor from my PM mill. Matt explained to me that the factory receives the motors without nameplates and puts an appropriate nameplate during the machine assembly, depending of the destination country. A reputable company would never do something like that. Different frequency requires different voltage supply. I have my doubts that a good 220 V, 60 Hz motor will work properly in your machine. Your voltage would be too high for it. Matt should never told you that using 60 Hz motor is OK, but using his own words, he is not an expert, he is just trying to sell more machines...

Regardless of the frequency the reported current is way too high for a good motor with no load. I would say you should be seeing around 4 Amps, and not 19.5 A. This is the reason for overheating. It could be a bad motor or a bad running capacitor or a bad centrifugal switch inside the motor. Please make a demand to Matt to replace the motor with a good 50 Hz, 220 V one. And let us know how he responded to that.


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## borris (Oct 29, 2014)

It could be a bad winding causing the motor to run out of balance and with less output which could cause overheating.


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## tino_ale (Oct 30, 2014)

Thanks all for your input.

The factory has replied to Matt that the temp are "normal", but he is having a hard time believing that is correct for a free running motor. Even if that is true, that would be heck of an inefficient setup IMO !!
Matt is going to try the temp test, to compare with my results, as soon as he can get an IR temp device. I am glad he is trying to figure out what is going on with me.

I realize most of you think I should get the replacement motor right away and stop wasting my time with what appears to be a defective unit, BUT being in France :
- shipping a new motor involves some cost and delay
- I don't know if customs will want to charge the 20% tax, being a replacement unit (don't know about that one really), that is a possibility
- if the problem is the 50Hz vs 60Hz issue, I would have the exact same issue with the replacement motor. I don't think Matt has "proper" 220V/50Hz motors. I suppose what I will get is an identical spare unit.
- Matt will not be able to test the replacement motor on 220V/50Hz prior to shipping it to me

This is why I am trying to push the investigation on my end. It is not my job and in an ideal world it should not be my problem but if I find the issue and if it is an easy fix, it would be a preferable outcome than swapping the motor out. Especially if the new motor doesn't solve anything, which is a possibility.

Matt has sent me a picture of the wiring on another PM1236. It is not identical. Maybe this is where the issue is, but maybe not. The factory may not be consistent in the wiring color they use. I need to open the electrical box and find out where my motor wirings come from.

OK there might be an issue with the centrifugal start switch, I would like to check that one too, if I can access to it : where is it located ?

Lastly, I have seen some VFD videos on youtube. Man, those motors seem to run butter smooth. I am tempted. I am now chewing on the idea of an upgrade.
For $333 I can have the standard 3-phase motor with a Hitachi VFD shipped. For $150 more I can upgrade for the better Leeson 3 Phase Motor. So for a little less than $500 I would get a good quality VFD setup for my PM-1236 and I would rule out any 50Hz VS. 60Hz issue.


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## tmarks11 (Oct 30, 2014)

mikey553 said:


> I can b machine. Your voltage would be too high for it. Matt should never told you that using 60 Hz motor is OK, but using his own words, he is not an exper.... This is thet could be a bad motor or a bad running capacitor or a bad centrifugal switch inside the motor. Please make a demand to Matt to replace the motor with a good 50 Hz, 220 V one. And let us know how he responded to that.



Here is an interesting bit of info:

If a single phase motor is moved to a new frequency domain the operation of any rotational switch must be checked.  A 60Hz motor in a 50Hz application turning 20% slower may not achieve a speed sufficient to open the centrifugal switch.  This would likely result in an immediate burn out.

Hmm, sounds familiar.  Some more good info here:
http://www.eng-tips.com/faqs.cfm?fid=1224


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## John Hasler (Oct 30, 2014)

In my experience the vast majority of small single phase induction motors are designed for 50/60 operation even if they aren't labeled that way.  It's cheaper than producing two motors of very slightly different design.


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## GA Gyro (Oct 30, 2014)

Again, just my $0.02...

If you decide to go the $$$ route (that is, get a 3 PH motor and Hitachi VFD)... I would go ahead and spring for the Leeson motor.  

The subtle details of better quality things working properly, to me, are worth the extra $$$.  

Be interesting to hear what Matt learns from the 'temp test'.


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## tino_ale (Oct 30, 2014)

Indeed IF I go with the VFD I'll get the better motor.

I usually prefer the "buy once, buy good" strategy, whenever I can.


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## mksj (Oct 30, 2014)

The VFD route gives very smooth and stable lathe RPM at various speed setting, you get soft start and with the added advantage of using it for  braking (You cannot use the manual foot brake and VFD brake at the same time, so a foot operated brake switch would need to put the VFD into free run stop). With a braking resistor (an inexpensive 50ohm 500W off of eBay), my lathe stops within ~1 second up to 1200RPM. I just installed a MacTach meter (see below) and get almost no deviation in RPM with the VFD (with the proper program settings).

The Leeson and Marathon Metric series 3 phase motors are reasonably inexpensive in the US, probably would use something along the lines of the Leeson 1992205.00 or Marathon R319A (2HP). You need to verify the motor frame type. With a VFD you are running variable frequency, the base frequency for the motor would be 60Hz, 230V. The usable frequency range for this motor would probably be 10-90Hz, so probably around 250-2500 RPM. My understanding from what Marathon motors literature has indicated that the maximum RPM is ~2X the base of 1800, but I wouldn't want to push them that high. You might see if this vendor ships to France? 

http://www.electricmotorwholesale.com/LEESON-192071.html
http://www.electricmotorwholesale.com/MARATHON-R319A.html

You might be able to work something out with Matt and get a Hitachi WJ200 VFD, either the -015S or -022S model. I have spent quite a few hours tweaking the program parameters for the WJ200-15S on my 2Hp lathe and would be happy to share the settings, or send the VFD motor settings in a file. Of course there is some individual tuning for the specific motor used and controls. It is very important that you are comfortable with the installation, as wrong wiring could be very dangerous. There is a lot of information on the web about lathe/mill VFD installations, this is a nice installation review for a Grizzly Lathe http://www.projectsinmetal.com/wp-c.../Install-VFD-on-Grizzly-G0602-10x22-Lathe.pdf .

There is also this posting for installing a VFD on a PM1236 with PDF instructions for the WJ200. Very nice, although there is no reason to cut a hole in the door for the VFD. Mine is also mounted in the cabinet, the door closes completely over the VFD. Under normal use, you do not need direct access to the VFD or it's display.
http://www.chaski.org/homemachinist/viewtopic.php?f=42&t=96363
PDF Instructions: 
http://www.chaski.org/homemachinist/download/file.php?id=36080&sid=e411b7d0d43ddd6cf089ce6cc6baed6c


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## mikey553 (Oct 30, 2014)

mksj,

I've got a Hitachi WJ200-022SF VFD for my mill with 3 HP motor. It is not operational yet, but I would appreciate if you can share the VFD settings with me. I realize my motor is different, but programming should be similar. Hitachi manual is not very user friendly and I would welcome any help I can get.


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## GA Gyro (Oct 30, 2014)

mikey553 said:


> mksj,
> 
> I've got a Hitachi WJ200-022SF VFD for my mill with 3 HP motor. It is not operational yet, but I would appreciate if you can share the VFD settings with me. I realize my motor is different, but programming should be similar. Hitachi manual is not very user friendly and I would welcome any help I can get.



My PM935TS (belt/pulley drive, 3HP, 3PH) with VFD just arrived today... have not unpacked it beyond removing the plastic and getting it inside the basement (had to remove the door and put it back in); will start a new thread on it.  

In a few weeks, I probably will contact you if you are willing to share the fruits of your understanding of the Hitachi VFD.  

THX

GA


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## mws (Oct 30, 2014)

tmarks11 said:


> Here is an interesting bit of info:
> 
> If a single phase motor is moved to a new frequency domain the operation of any rotational switch must be checked.  A 60Hz motor in a 50Hz application turning 20% slower may not achieve a speed sufficient to open the centrifugal switch.  This would likely result in an immediate burn out.



Acknowledging that the reduction in operating parameters for a 60Hz motor operating at 50Hz is significant, it is NOT "dramatic" for this application.  If this motor were operating at full load, 100% duty cycle in a pump or blower application it would be far more pressing. In an intermittent machine application like this I would be reluctant to attribute much, if any, of the problem on design operating frequency.  
As far as the centrifugal switch is concerned, these switches are intended to open as soon as the motor achieves positive rotation, maybe no more than 20% of their operating speed; this is well within the reduced speed envelope of a 60Hz motor operated at 50Hz. 
Such a high operating current (19.5 Amp @ no load) is indicative of a very high magnetic current in the motor. This can be caused by a)mechanical load, b) a reversed run winding c) a shorted run capacitor, d) shorted turns in a winding or e) a bucking winding (start winding energized).

Without belaboring the various intricacies of  each circumstance... a) is eliminated, b&c) would likely result in a locked rotor or trip a breaker, d) is a definite possibility although shorted turns usually result in smoke after a short time, which this hasn't. That kind of leaves e) as the remaining culprit.  

To answer your question regarding where the centrifugal switch is, it's usually located in the rear bell housing of the motor. The weighted mechanism is on the motor shaft and the switch resides on a fixed position in the bell housing. They're pretty simple.  

I'll be eager to find out just what is the actual problem.  As much as I'd like a VFD on my machine, I think I'd spend a little time wrenching on this problem before I threw in the towel if this were in my shop.    Best of luck to you. 

Mark


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## mksj (Oct 31, 2014)

The centrifugal start switch is a function of motor speed, load should have no effect on it. "After the motor has reached approximately 75 percent of synchronous speed, the main winding can develop nearly as much torque as the two windings. Thus, an electromechanical centrifugal switch mounted on the rotor can be a simple and effective speed sensitive mechanism to cut out the auxiliary winding once the motor has picked up 70 to 80 percent of synchronous speed." http://dspace.jdvu.ac.in/bitstream/123456789/19524/1/Acc. No. DC 264.pdf

Better built motors may be more tolerant of variations in frequency and voltage.  Given that the individual mentioned in my posting above on the PM1236 VFD conversion went through two stock single phase motors in a short time period before Matt recommended switching it to a 3 phase unit, does not instill confidence in the quality or reliability of the motors used. A defect in the wiring or windings would cause smoke, or the motor not achieving rated speed for the 50Hz. A bad motor start capacitor, the motor would not start. The high running current draw is consistent with the usual motor start amperage "current draw may be as much as 3 times the FLA (full load   amps) during startup", so agree that the most likely issue is the centrifugal switch.  Take the motor apart and see what you can do with it, possibly the centrifugal switch is sticking or sticking contacts. I do  not think it is reasonably to try to change the switch release characteristics or alter the motor, for an item covered under warrantee. A replacement motor may not be subject to VAT  "Replacement goods exchanged for goods exported for repair", but France may be different. So you may only have to pay the cost of shipping a new single or three phase motor if you go that route.

I will post the suggested WJ200 VFD programing parameters once I get time to put it in a tabular format.


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## tmarks11 (Oct 31, 2014)

mws said:


> As far as the centrifugal switch is concerned, these switches are intended to open as soon as the motor achieves positive rotation, maybe no more than 20% of their operating speed; this is well within the reduced speed envelope of a 60Hz motor operated at 50Hz.



Baldor and Leeson both spec their motors with a centrifugal switch that opens at 75% of rated speed.  

http://www.leeson.com/TechnicalInformation/sphase.html

A 60 Hz centrifugal motor built for 3450 rpm speed operated at 50 Hz will be running at (50/60)*3450 =2875 rpm.

10 Hz decrease in frequency = (10/60) = 17% decrease in speed.

So the centrifugal switch SHOULD be opening. So if the centrifugal switch is a bit off (on a Chinese motor? unthinkable), the switch could stay shut.  Leaving that starting winding engaged could easily explain the extra current draw.

I personally would source a local 3 phase motor and VFD, and stop wasting time.  See if Matt will refund you the cost of the replacement motor he would have supplied. You will be happier with the performance in the end as compared to whatever cheap motor came installed on the machine.  This is a common upgrade to get rid of vibrations (3 phase motor is smoother) and give you finer control of spindle speed.


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## tino_ale (Oct 31, 2014)

Thanks for the thoughts folks.

I'm waiting for Matt to perform the temp test.

I'm chewing the VFD idea. Matt proposes Hitachi WJ200-015SF for $280 + a Leeson 2HP 3 phase motor for $150 if I want that better motor instead of the replacement 1 phase motor, or standard 3 phase motor. With shipping that will set me back just a tad less than $500, that was not an expense I expected to make that soon, so it gets me thinking. Dilema dilema! It would be a nice setup though.

Thanks for offering help on the Hitachi VFD. Seems several people are insterrested too, might be the time to create a thread for that Hitachi VFD topic, there's probably much to say about all those settings.

I also need to get comfortable with the lathe wiring to modify it to VFD. I need to go through the stock wiring diagram, see if I can relate to what I see on my lathe. If I do then I should be able to modify it to VFD. Kudo on the PDF documentation, that will be a huge help if I go that route.


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## tmarks11 (Oct 31, 2014)

tino_ale said:


> Matt proposes Hitachi WJ200-015SF for $280 + a Leeson 2HP 3 phase motor for $150 if I want that better motor instead of the replacement 1 phase motor, or standard 3 phase motor.


That would be a killer upgrade if he offered it to every new purchaser.  Except for the overseas shipping costs (ZOINKS!) it would be a no-brainer.


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## chuckorlando (Oct 31, 2014)

I commend you on your patience. I'm not sure I could jump through so many hoops if the machines under warranty. If you done nothing wrong, I dont think you should incur any cost at all. If it was me I would see about a credit for replacement cost then source my own set up and use the credit on other things.


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## Falcon67 (Oct 31, 2014)

tino_ale said:


> I'm chewing the VFD idea. Matt proposes Hitachi WJ200-015SF for $280 + a Leeson 2HP 3 phase motor for $150 if I want that better motor instead of the replacement 1 phase motor, or standard 3 phase motor. With shipping that will set me back just a tad less than $500, that was not an expense I expected to make that soon, so it gets me thinking. Dilema dilema! It would be a nice setup though.
> 
> .


That's a real good price on those pieces.


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## tino_ale (Oct 31, 2014)

Matt is offering to replace the motor at no cost for me, including shipping costs, although they are normally not covered. What is left to me is a possible 20% customs tax that I'm not sure about, depending on my luck I guess.
So I have that option available.
Or, I can use that credit for a better deal on the VFD upgrade. That's where the dilema kicks in !

About my patience, hell yes, I think I have been patient... actually you have no idea. That motor issue is almost nothing.
The order of my lathe has been extremely long, for various reasons, it made it to my door one FULL YEAR after the full payment.

I found out right here on this forum (Matt never told me) that it seems it is my order that triggered the whole metric machines story. There has been other issues with my order (missing parts among other things) that have now been resolved. Now the motor issue... Looks like there is some really bad karma surrounding my first machine purchase.
It is safe to say it's been a major PITA for both Matt and I, but I've waited so long to place that order, years litteraly, that I want to make things right even if it takes some additionnal efforts.


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## John Hasler (Oct 31, 2014)

> I personally would source a local 3 phase motor and VFD, and stop wasting time.



I personally would tell Matt that the motor is clearly defective under warranty and that I want a replacement.

I would also want to know why the machine is drawing .35A when supposedly turned off.


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## GA Gyro (Oct 31, 2014)

IMO the upgrade to a 3 PH motor and VFD is an idea worth seriously considering!  

AS I understand the thread:  Matt is offering to either send you a new 'stock' motor, or credit you for that motor towards the VFD and Leeson.  

IMO the latter might be worth serious consideration.

There is a thread somewhere in the PM forum, by MJKS (did I get that screen name wrong), about his mods to a 1340GT with a VFD.
IMO the VFD upgrade is gonna be some serious elec work, it will stretch the average person who does not understand electricity well.  
Having said that... I suspect the folks on this forum will help.  
Personally, I would do all the research until I felt like I understood how to do it... Then find a local person who understands these things and pay them to come over and help with the wiring.  In US$'s; an investment of around $50 for a couple of hours help... would IMO be money well spent.  

Just my $0.02 worth... 

Glad Matt came through for you on replacing the motor... a significant part of why I chose to go with PM products was/is Matt being an honest guy that understands customer service.  Usually, one gets what they pay for... rarely does one get the lowest price with the highest customer service... 
For me, the customer service is more important than getting the rock bottom deal.  

Hope this helps.

GA


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## mksj (Oct 31, 2014)

In the long term, reading the motor issues with the stock single phase Chinese motor, a VFD conversion may ultimately be in the cards. That is excellent pricing for a WJ200 VFD and 2HP 3 phase Leeson motor.

I went over the top in my VFD conversion, mostly because I had a specific set of functions and interlocks I wanted to incorporate. I also had the time and background to do a more complicated set-up, and I would not recommend that level of complexity/build unless you are very familiar with doing so. It is always a learning exercise, at first I was quite intimidated by the whole process and the complexity of the command structure of these types of VFDs. That being said, it is a problem solving challenge, and you do it in a stepwise fashion. 

I would keep things simple for most VFD installs, the PDF description for the PM1236 is very straight forward and very cleverly done.  I would get rid of the Jog direction switch and the green wire connection to the reverse terminal 10, see revised schematic adaptation. Also note that one should not use a manual lathe brake and the VFD brake at the same time. This is not addressed in the original schematic. I do not see this as a big issue, it may or may not be cause a problem, but the VFD brakes using a programmed algorithm you specify. If the manual brakes is faster than the VFD electronic brake, the VFD may add power to match the programmed braking curve.  I use an electronic 1 second braking time so probably not a problem with this quick an interval, and may not require the additional foot switch/command.

It is possible to do the VFD conversion in a basic form with very little effort or changes to the system. If the most rudimentary conversion form, one could easily remove the 220V power to the forward/reverse contactors. Then connect P24 to one set of the contacts in the forward and reverse contactor  to send commands to the VFD for the forward/Reverse commands. This retains all the safety and interlock features. The Jog function on the Hitachi requires two commands to be sent to the WJ200, Jog command and Forward or Reverse command at the same time. I see no reason to have a reverse Jog, so one just powers the existing jog switch from P24. When the jog button is engaged it connects P24 to the VFD terminal 3 JG and a diode (1N4001, 1N4004 or similar) wired to VFD terminal 1 (FW). The diode must be used, otherwise when the forward signal command is engaged it would backfeed the Jog command. Been there, done that.

The VFD is direct wired to the motor, 3 wires (should be shielded 14G). You need a breaker/on off switch to power up everything. Take it one step at a time. I will post the suggested programming variables when I get time. 

Mark


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## mws (Oct 31, 2014)

tmarks11 said:


> Baldor and Leeson both spec their motors with a centrifugal switch that opens at 75% of rated speed.
> 
> http://www.leeson.com/TechnicalInformation/sphase.html
> 
> ...



Yep, the switch SHOULD be opening.  Given the distinct click heard on the video when spinning down I think the mechanism is definitely tripping on start-up. Whether the contacts open...  Also, the motor appears to be a "cap start/cap run motor. A shorted run cap would be as bad, or worse, than a stuck start switch.  75% rated speed sounds like a lot for the start winding to drop out from my experience but I can't argue with the manufacturer.
Thanks for the link.


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## jgedde (Oct 31, 2014)

19.5 amps no load is DEFINITELY an issue.  That motor has a shorted winding or a miswired loop.  I think if Matt sends you a replacement all will be OK.  That motor is no good for sure!  Even at 50 Hz, the motor should work fine (albeit with reduced efficiency).

All in all, if it were me, I'd consider a 3 phase motor and a VFD.  Motor vibration from the single phase motor does put a limit on surface finish....

John


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## tino_ale (Nov 2, 2014)

Hi guys,

I've checked my motor wiring, it is correct. Not identical to the pic Matt sent me, but correct none the less. The issue seems internal to the motor, definitely.

Now considering that motor has to be replaced, I can either use the credit for a spare unit, or use it towards the VFD and better motor upgrade.
I did not plan for that expense that soon, but I felt it would be somewhat a waste to use that credit for a low quality single phase motor, even one running ok, considering I would like to upgrade to VFD eventually. Well it's going to be sooner than later !

So, you got it, I bit the bullet with the 2HP Hitachi VFD and 2HP 3-phase Leeson motor. :shush:

The installation will be an experience and probably a learning curve but considering the very helpful crowd I find here, the schematics... I feel I will make this happen. I will take my time and go step by step. I'll share how it goes for sure.

Thanks again all.


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## chuckorlando (Nov 2, 2014)

You made the right call. If I have a motor or engine go south prematurely, I always feel uneasy with the same style replacement.


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## GA Gyro (Nov 2, 2014)

Both of my PM machines were ordered with 3PH motors... added the VFD's.


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## mksj (Nov 6, 2014)

Programing parameters and instructions for Hitachi WJ200 poster here: http://www.hobby-machinist.com/show...-to-the-control-switches-on-a-PM1340GT-lathe?

Hopefully you can use these parameters as a starting point for your PM1236. Let me know if you have any questions.


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## tino_ale (Jan 24, 2015)

Ok update time :whistle:

I have received the Hitachi VFD along with the Leeson 3 phase motor.

I have wired just the two of them, on a bench just like a mockup, also with the 1k pot. I have wired the motor for low voltage. Then changed the few mandatory parameters to make it work, fired it up : it is alive !
So far so good!

Now I need to do all the wiring on the machine. I was going to wire it exactly like described in this PDF disconnecting the mechanical foot brake and adding the reverse jog selector.
I have noted the schematic noted in this PDF and for the most part I think I understand it but I realized I could not be easy on my gears and have a fast and strong emergency stop. So, I would like to make something slightly different and I could use your help.

I would like to have a normal operation brake setting, say 5 seconds, separate from an emergency brake setting that will be as fast as the VFD can take (I know I will need to source a braking resistor), 1 second or so. That emergency brake will never be used except, well, in case of an emergency.

The emergency stop has to be activated if :
- E-stop is triggered
- foot brake is activated
- gear cover is opened
- chuck guard is opened
Basically any danger situation triggers the emergency brake. Normal operation uses the soft stop to prevent wear and tear to my gears and make my lathe last for years .

Does anyone know how I should wire this string of 4 interruptors ? The emergency stop has to override any other input including jog, and use a separate brake setting. Also after an emergency stop (any of the 4 interruptors), the lathe should not resume power unless I return to neutral first.

Has anyone done this before ?
Any advice welcome!


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## mksj (Jan 24, 2015)

I do not feel that it causes any problem to have a 1 or 2 second stop time programmed in. Even with a 1 second programmed in the WJ200 (which is what I use), the faster the RPM the longer it takes to stop, so at least 2-3 seconds from the higher RPMs and it is very linear as opposed to jarring like the mechanical brake. (I set my deceleration to a linear line as opposed to the S curve).  When you consider what the gears go through with the starting and stopping without the VFD, it should not be an issue for the gears with a VFD.  

Should be very easy to have two different braking speeds, which schematic are you working off? I need to look at the programming, but one should be able to switch between a 1 step (quick) and a 2-step (default, slower) deceleration using an additional programmed input terminal.


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## mksj (Jan 25, 2015)

<!--[if gte mso 9]><xml>  <w:WordDocument>   <w:View>Normal</w:View>   <w:Zoom>0</w:Zoom>   <w:TrackMoves/>   <w:TrackFormatting/>   <wunctuationKerning/>   <w:ValidateAgainstSchemas/>   <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid>   <w:IgnoreMixedContent>false</w:IgnoreMixedContent>   <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>   <woNotPromoteQF/>   <w:LidThemeOther>EN-US</w:LidThemeOther>   <w:LidThemeAsian>X-NONE</w:LidThemeAsian>   <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript>   <w:Compatibility>    <w:BreakWrappedTables/>    <w:SnapToGridInCell/>    <w:WrapTextWithPunct/>    <w:UseAsianBreakRules/>    <wontGrowAutofit/>    <w:SplitPgBreakAndParaMark/>    <wontVertAlignCellWithSp/>    <wontBreakConstrainedForcedTables/>    <wontVertAlignInTxbx/>    <w:Word11KerningPairs/>    <w:CachedColBalance/>   </w:Compatibility>   <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel>   <m:mathPr>    <m:mathFont m:val="Cambria Math"/>    <m:brkBin m:val="before"/>    <m:brkBinSub m:val="--"/>    <m:smallFrac m:val="off"/>    <m:dispDef/>    <m:lMargin m:val="0"/>    <m:rMargin m:val="0"/>    <m:defJc m:val="centerGroup"/>    <m:wrapIndent m:val="1440"/>    <m:intLim m:val="subSup"/>    <m:naryLim m:val="undOvr"/>   </m:mathPr></w:WordDocument> </xml><![endif]-->  Two braking algorithms for the WJ200:

To use two different braking algorithms (short 1 second and long 5 seconds), connect a wire from terminal N-13 in the above diagram (any point after the last interlock switch) to the next unused VFD terminal input (assume this is 4). You could also add a toggle switch in that input wire line, so for something like threading, you hit the toggle to the open position to get 1 second braking.


  [FONT=&amp]In the diagram above, this would be Input 4 (BR). Reprogram input 4 per page 4-22 of the manual, "Two Stage Acceleration and Deceleration" so set with option code "09". Set A093 to 4 seconds and set A094=0. Set first step of the deceleration F003 to 1 second (set F002 acceleration to 5 seconds, second acceleration time to A092 = 1 second). So whenever the relay is latched, and there is power to N-13, this signals the VFD to use 2-stage braking of 1+4 seconds. Anytime power from P24 is interrupted (or the signal to input 4 "BR" is broken), the machine would revert to 1 second braking (single stage). You could also still use the mechanical brake if you wanted to, you would just need the switch in the schematic that signals the motor to free run (no braking B091 setting 01 programmed to a separate input terminal), and this should engage when you press on the brake.[/FONT]<!--[if gte mso 9]><xml>  <w:LatentStyles DefLockedState="false" DefUnhideWhenUsed="true"   DefSemiHidden="true" DefQFormat="false" DefPriority="99"   LatentStyleCount="267">   <w:LsdException Locked="false" Priority="0" SemiHidden="false"    UnhideWhenUsed="false" QFormat="true" Name="Normal"/>   <w:LsdException Locked="false" Priority="9" SemiHidden="false"    UnhideWhenUsed="false" QFormat="true" Name="heading 1"/>   <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 2"/>   <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 3"/>   <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 4"/>   <w:LsdException Locked="false" Priority="9" QFormat="true" 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Let me know if this is clear, and if you want it added to wiring diagram/list of suggested VFD parameter changes.


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## tino_ale (Jan 26, 2015)

Hello,

This is the schematic I would base my wiring on (PDF file) :

http://www.chaski.org/homemachinist/viewtopic.php?f=42&t=96363

Thanks for the suggestion. I think I understand how it works. I'll edit the schematic later and post it here for a last review before I start crimping wires :talktogod:


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## mksj (Jan 26, 2015)

Schematic with dual braking adaptation. Do not really see the need for a forward reverse switch for the JOG. Let us know how it works out.


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## GA Gyro (Jan 26, 2015)

mksj said:


> Schematic with dual braking adaptation. Do not really see the need for a forward reverse switch for the JOG. Let us know how it works out.
> View attachment 93449



Thx Mark... may adapt part of this to my 1340 when it gets here.


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## tino_ale (Jan 27, 2015)

mksj said:


> Schematic with dual braking adaptation. Do not really see the need for a forward reverse switch for the JOG. Let us know how it works out.
> View attachment 93449



Looks perfectly fine, thanks !
I did not notice there was no light wiring before you added it, good eye!

I need to order all the missing parts :
- 3 x 1N4001 diodes
- 1 x 4-poles 24V relay
- 1 x 1k pot (got this one already)
- 1 x switch for reverse jog (I can see it usefull for taping in and out, etc)
- connections rail for all the 24V wiring

Looks like I have a plan
cheers


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## mksj (Jan 27, 2015)

With the VFD control, you can run the speed very low or to a stop when threading, then reverse and pick up the speed to back out. Essentially, you can set it like a JOG button, but not a big deal to add a F/R JOG switch. When wiring, I usually use 8 wire cord, so I have some spares (like for a 2 stage breaking switch). I recommend using a LED power indicator light (~30 mA) because of the low power draw, as the VFD bus can only supply 100mA (relay is about 60 mA). Also be aware that the relay connections in the socket are often different then relay itself.

I use a 22mm LED lighted switch for my JOG button, the LED is connected as shown in the diagram to indicate power is active. Use shielded cable for the speed pot and the input terminal controls, ground at the VFD. It is also recommended to use shielded cable between the VFD and the motor.


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## Dan_S (Jan 27, 2015)

mksj said:


> With the VFD control, you can run the speed very low or to a stop when threading, then reverse and pick up the speed to back out.



I wanted to point out, that you have to be careful doing this. Unless the motor is specifically designed to be used with a vfd (inverter duty rated), you can damage it buy running it to slow. Basically You can overheat it, because its cooling fan isn't running at it's designed rpm. 

I've head a lot of people recommend not going bellow 50% of the rated frequency and even then that's assuming your not putting the motor under heavy load.


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## mksj (Jan 27, 2015)

This applies to prolonged use, in this case you are only using the motor for a short period of time (if that). I normally use a range of 30-90Hz on my PM1340GT with no problems on a non-inverter rated motor. The Leeson metric motors he is using is inverter rated, very nice metric sized motor at a reasonable price.  As you mentioned TEFC should not be run for low speed for a prolonged period of time, as opposed to TENV motors.


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## Dan_S (Jan 27, 2015)

mksj said:


> This applies to prolonged use, in this case you are only using the motor for a short period of time (if that).




That's why I also mentioned the cavet about how hard you are working the motor. this page has a good example of another senario that people need to be aware of.
http://ecmweb.com/design/mating-new-variable-frequency-drives-existing-motors



> Using a VFD, with fundamental frequency being reduced to achieve lower speed, the voltage also is reduced in direct proportion to the speed reduction. As mentioned earlier, a 460V motor at half rotor speed will have 230V across its lines. Thus, if the motor's rating is 100 hp at full speed, its output would only be 50 hp at half speed.
> Certain loads, like lathes and grinders, require constant horsepower throughout their operating speed range. Let's assume a VFD is serving a 20-hp lathe motor that's operating at a 25% reduction in speed (3/4 rated speed). The lathe's rotating chuck, which holds some material being worked by a cutting tool, will need constant horsepower over the entire speed range being used. If speed is reduced by 25%, voltage will be reduced by 25%. For the motor to maintain constant horsepower output, it will draw 33% more current (4/3 of normal amperage). Because current produces heat (primarily [I.sup.2]R losses), the motor will have to have sufficient thermal capacity to handle the extra amperage.




with all that being said, the main thing to remember is that a VFD on a regular motor will work well for a long time, as long as you are relastic about what you are asking it to do.


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## AJB (Jan 28, 2015)

Dan_S,

You seem to have a very good understanding of VFD's.  In your opinion, what are reasonable upper and lower frequency settings? 

AJB


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## Dan_S (Jan 28, 2015)

AJB said:


> You seem to have a very good understanding of VFD's.  In your opinion, what are reasonable upper and lower frequency settings?



As my Uncle used to say, I know just enough to be dangerous. )


From what I have read, it has a lot to due with how much abuse the motor in question can handle. I have heard of people using 30hz - 90hz, and I've also heard 45hz - 75hz for a 60hz motor. Hopefully someone with more knowledge than me will chime in and explain how to determine whats a good range.


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## JimDawson (Jan 28, 2015)

I'm pretty much in agreement with Dan_S.  30 to 90 Hz is where I normally run mine.  Sometimes for very light cutting I'll go to 15 Hz for very short periods of time.  A 1800 nominal RPM motor is generally safe to run to 120 Hz, but I would not do that with a 3600 nominal RPM motor.  I do the large speed changes with the belts/gears, then use the VFD to fine tune the speed.


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## AJB (Jan 28, 2015)

Dan and Jim,

Thanks for the VFD advice.  I just installed my first one on a 2hp lathe and set the range for 50-70hz.  I felt like this was very conservative  but I wanted to protect my motor.  Based on what you guys are saying I may increase the range a bit.

AJB


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## mksj (Jan 29, 2015)

The context of the low speed use was for jogging direction, whether this is done by hitting the JOG button or using the variable speed pot is irrelevant. It would be unwise to operate the VFD motor at low speeds for any length of time.

   Just to add some clarity on the discussion of 3 phase motor speed ratings with a VFD, this is specific to the machine design specification,  application requirements and the motor/VFD used. We are talking about non-CNC hobby application type lathes that are not run in continuous mode *at full load*.  If you look at most factory supplied lathes in the 12-14x40 range with variable speed VFD operation, they usually have two mechanical speed ranges to cover a 50-2500 RPM speed range (example: SHARP 1440V with a 3HP motor). In most cases the motor is up-sized by 50-100% to cover the broader operating range needed with 2 mechanical speeds. The VFD operating RPM range is ~10 fold.  There is no free lunch, and one needs to understand that horsepower drops off in a linear fashion below the motor's base speed, and torque falls off above the motor's rated speed in a somewhat linear fashion to 1.5-2.0X the motor's base RPM. That being said, if you have a 6-9 speed lathe, as you go shift to a lower speed range you amplifier the motors rotational force to the lathe shaft. There is also a big difference power requirement difference if your threading a 1-2" rod vs. turning a large diameter piece.

  Regarding operating speed of most inverter rated 3 phase motors, there are many factors that come into play (electrical and mechanical). In my discussion with motor manufactures, many rate their 1800 RPM 3 phase inverter 2-5Hp motors to 1.5-2X their base speed. Vector duty motors are usually rated a bit higher "Vector Duty and Inverter Duty motors from Marathon Motors are designed for operation at 150% of rated load for one minute, up to the base speed of the motor (overload capability declines to 100% as the motor reaches maximum constant HP speed). These motors accommodate constant horsepower operation to 1-1/2 to 2 times base speed, subject to the motor's maximum safe mechanical speed limit." Most 3 phase inverter rated 3 phase motors have constant torque range of at least 10:1, so in theory would allow constant torque down to ~200 RPM.  http://www.marathonelectric.com/docs/2014-SB300.pdf






http://www.vfds.com/blog/vfd-buying-guide
  "Generally speaking, a motor should not be run at any less than 20% of its specified maximum speed allowed. If it is run at a speed less than this without auxiliary motor cooling, the motor will overheat. Auxiliary motor cooling should be used if the motor must be operated at slow speeds".

This is the bases for a 30-90Hz VFD operating range as being a reasonable operating envelope in this particular application.


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## tino_ale (Jan 30, 2015)

Thanks for the good info.

Over here we operate things under 220V / 50Hz.
I'm going to stay in the 25Hz-75Hz range to be safe.



> I recommend using a LED power indicator light (~30 mA) because of the low power draw, as the VFD bus can only supply 100mA (relay is about 60 mA).


Actually, I need the stock 24V AC-DC converter to power the carriage work light, so I'm going to use that output as a 24V source. No issue keeping to non-LED status light.



> Also be aware that the relay connections in the socket are often different then relay itself.


Not sure I got that one, do you have a pic or diagram showing what you mean ?

I have not sources my parts yet. Just too much stuff on my plate at the moment...


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## mksj (Jan 30, 2015)

Hi Tino,

You need to set the VFD settings based on the motor nameplate,  not the line in. So if you were sent a Leeson Metric 3 phase  60Hz motor at 230V, then that is the  base frequency and motor voltage (also check the RPM and Amperage). You can also run an auto-tune to get  additional motor parameters.

If you have a separate 24V power  source for the power indicator light, then you need a separate switch  or relay to connect it. You cannot use two power supplies in the same  circuit if I understand your description. You can use the 24VAC  transformer for the machine work light. 

So you need to wire the relay in accordance with the socket base diagram, not the relay diagram, as the location of the connections are different.


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## Blackhawk (Apr 18, 2016)

So the only option is to replace motor?

I've only used mine to turn about 10 barrels and it has the same symptoms. Of course I'm out of warranty.

Lanham


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## mksj (Apr 18, 2016)

Go with a Leeson/Marathon metric motor and a VFD. World of difference. I have done systems for the PM1236, if you go with a Hitachi WJ200 I have all programming parameters, etc. I can send you. Otherwise, just replace the motor with a good quality single phase TEFC from Baldor. Marathon, Leeson, Lincoln, etc. and move on. The stock 3 phase motors on these machines, tend to be pretty crappy anyway. The problem with the single phase replacements is that they will be NEMA frames sizes, so you may have fitment issues, and need to check the motor dimensions with your machine.


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## tmarks11 (Apr 19, 2016)

Just so you are not shocked: expect your new Leeson motor to say "made in China" on it.  Only a few types of Leeson motors are still made in the US.


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## tino_ale (Nov 4, 2016)

Ok so I'm kinda waking this dead thread because I still haven't performed the VFD conversion. I do have the motor and Hitachi but have not had the time to take care of it. Shame on me !

As I want to move forward, and have used the lathe more, I have an idea of the jog button that I wonder if it makes any sense.

CHANGING GEARS. It can be a PITA to change gears on the 1236, you have to wiggle the spindle to get a shot at gears engagement. It is just not practical at all.

So I am thinking. What if, during forward or reverse operation, say I need to change gear, I press the jog button while still running, that action slows down the RPM to a very low value (only used for a short time and under no significant load so no danger for the motor), I change gears while running super slow, then release the jog button and the motor speeds up to the previous speed setting.

Jog speed would be a fixed parameter, very very low. Jog would run in forward or reverse depending on what was engaged. It would be a kind of temporary speed setting override.

If pressed while in neutral, it would run at the same slow rate in forward or reverse, based on a toggle switch.

Does that make sense and is that even doable ?

I am thinking maybe this need to be addressed by two separate switches :
- the "real" jog (only working when in neutral) as it is in the skematic
- the speed override that only works when running in either reverse or worward
If the two can be combined that would be nice but I don't see how that could be achieved in the skematic.

Any thoughts ?

Cheers


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## tmarks11 (Nov 4, 2016)

tino_ale said:


> OCHANGING GEARS. It can be a PITA to change gears on the 1236, you have to wiggle the spindle to get a shot at gears engagement. It is just not practical at all.....say I need to change gear, I press the jog button while still running, that action slows down the RPM to a very low value...



Very typical to have the JOG button wired to tell the VFD to run the motor at 5 Hz (my VFD even has a connection labelled "JOG" in the manual). I don't think that is slow enough to prevent damaging your gears during engagement, depending on what gears you are talking about.

If you re talking about changing speeds, then the fastest gear in the gearbox at 5 Hz will be running at about 75 rpm... more than 1 revolution per second.  That is very fast to be jamming against another gear.  I don't think you would be happy with that.

If you are talking about the feed/threading gears, those are geared down quite a bit, so at 5Hz on the motor, they are probably only going 10 rpm or slower.  Probably okay.

But lets backup....

First of all, with the VFD, you can (for the most part) leave the gearbox speed selection in one position (except for maybe the HI/LOW gear), and control the speed with the VFD.

Second, what you describe is typical of EVERY gear head lathe, not just yours.  They all require rotating the spindle by hand to get them in gear.  Chances are 70% that when you go to mesh two gears together, the teeth won't be aligned.  Machinists for 70 years have been rotating the spindle to change gears.  "Not practical at all"?  I guess beauty is in the eye of the beholder.

You should try a belt driven lathe where you have to move belts around to change speeds....


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## mksj (Nov 4, 2016)

Agree with Tmarks, you almost always have to turn the chuck to get the gears to engage.

The Jog speed is adjustable, the default is usually 6Hz, how fast it turns the gearbox gears is a function of the spindle speed gear selection, the gearbox speed will vary depending on the gearing. The difference in jog is that there is no braking applied so there is some momentum and the head will spin (free whweel) a bit to a stop. So that would be the time to shift gears, a bit like turning the chuck to get the gears to mesh. Changing the gearbox while pressing the jog may not be such a good idea no matter what the Hz/speed, as the VFD can apply full rated torque almost down to 0 RPM. So if something does not mesh well or binds, it may break. But I do sometimes bump the jog and when the chuck is almost stopped, I will engage one of the feeds if not fully engaged.   Also when Ever I do change gears, either spindle or the gearbox, I always pump the jog to make sure it is fully engaged before running at regular speed. It verifies gear engagement.

I also recall more than one post where there where shifting issues with the PM1236, and it had to do with the key in one of the gear shafts being bent.


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## tino_ale (Nov 5, 2016)

Very right about the spindle speed gears, for the most part VFD will make it a breeze to adjust speed without having to change gear.

What I had in mind was the feed/threading gear box. On the 1236, the carriage power feed is much faster than the compound feed, on any given gear selection. Meaning that when I'm for example finishing a part to what I'm trying to make a "perfect" finish, I have to finish the OD with one feed setting, then swap to another setting and do the facing.

That being said, I think I need to follow your advise here because as you said, if I change gear while under motor power, regardless of the speed at which it is set, any binding or stuck gear will end with something broken.

Thanks for you valuable inputs! Now I need to shop for all those electrical parts and wire up the system. I'm going to stick with the standard Jog function as described in the page 2, post #58.

Just so I get it right : I'm going to disconnect the physical brake and go with the two deceleration rates option :
- If the "forward" or "reverse" signal is simply lost but the BR signal is still here, it means there is no emergency => 5s slow stop.
- if the BR signal is lost, it means one of the security switch is opened (E-stop, cover...), the FW/RV signal is also lost => strong stop in 1s. And, the machine will not restart until back to neutral and ready (all security switches closed first).

If I understand the schematic correctly, I do not need the second foot brake switch, the one at the very bottom of the schematic.
All I need is to wire a "security" string of switches in series, and feed both the FW/RV switches and a custom analog entry (BR) with that signal.

Do I get this right ?


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## mksj (Nov 5, 2016)

Yes, if the brake switch goes open and is serially connected, it acts like an E-Stop. If using 2 stage braking, it will revert to 1 stage when the E-stop or any of the safety switches go open. Its been a long time, and I no longer use the single relay design, so I need to review it. I would leave the physical brake connected and try it as is, since the VFD will stop it quicker than the physical brake. The physical brake is sometimes helpful when the you want to lock the chuck for manual tapping, etc. 

An alternative if you just want it up an running with the VFD, is to just disconnect the high voltage power to KM1 and KM2, and use them to switch input 1 and Input 2 on the VFD. The motor is directly connected to the VFD. Yhe Jog will work at the speed pot setting, if you want the Jog at a Jog speed it needs to be reconfigured to activate input 3 and Input 1 for forward jog.  There is also the issue that the once the contactors have been used for high voltage, the contacts get some resistance from arching and may not conduct low voltage signals.


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## tino_ale (Nov 6, 2016)

Thanks for the confirmation. I like the way it works, it is exactly the behavior that I have now except that all security switches will have brake applied instead of just the foot brake. So it is pretty much an improvement in terms of behavior. I looks like I can do my shopping.

I'm not sure I understand your second paragraph. I just reached the point where I think I understand the schematic you provided, lol. I want to make the conversion with all the safety interlocks and brake abilities that we talked about so I'm sticking with your first schematic.

Thanks for your invaluable help


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## jbolt (Nov 6, 2016)

I set my lathe up with 2-stage braking but kept the manual brake. I prefer to have the manual brake for safety. The manual brake will stop a large chuck from full rpm faster than the VFD. If the VFD faults it freewheels. The foot brake is also quicker than hand lever.


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## tino_ale (Sep 9, 2019)

So.... may sound like a joke, but I'm just completing my VFD conversion now. That's what a newborn will do to your hobbies apparently 

Anyhow, I've done the bulk of the conversion and I have it working 75%

I have a defective jog direction button that I need to replace
I have not re-wired the status light yet, I just need to buy a LED light to limit current draw from the 24vdc VFD supply
I am not entirely sure if the "no resume on startup after power loss" works, I need to double check that one
I have not programmed the two speed dynamic braking but I know what to do (thanks to you), and it's only one wire more than my current setup

I dit not have shielded wires on hands, so I went ahead without, that may be the next upgrade down the road...

I have all these things covered and I can't thank you enough for the inputs. Using the schematics has been invaluable. Now that I've wrapped my head around the global logic of the interlocks, I think it is a KISS implementation, nicely done and elegant.

I am just a little confused about the initial settings that need to be done at the VFD for it to run the motor perfectly.
I have the Hitachi WJ200 VFD drive

I have noted down these parameters to run the motor in the 40-80Hz window :
- A003 Base Frequency : 60 Hz
- A004 Maximum Frequency : 80 Hz
- A011 Start Frequency : 40 Hz
- A012 End Frequency : 80 Hz (redundant with A004 ?)
- A082 Automatic Voltage Regulation : 230 VAC
- B012 Motor Current Rating : 5.4 Amps
- H004 Motor Poles Setting : Four Poles

Am I missing anything that should be initialized ?
Also should I / how do I use the "auto-tune" feature ? Is it actually needed to run the motor at it's peak performance ?

Thanks for any input
BTW, the smoothness of the setup is just beyond my expectations. If I had known I would have ordered the lathe with the VFD setup from day 1.


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## mksj (Sep 9, 2019)

The parameters should be pretty much the same as the Basic VFD COnversion (see below). Top speed on the motor probably 80 hz. The WJ200 just has the motor kW, no amps, 4 pole is the default. Make sure the correct motor voltage is set, I believe it is 220V.   Run the autotune after everything is setup and working.


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## tino_ale (Sep 10, 2019)

Thanks !

I have already set the core parameters (not all that are listed in gree in this document, some of them seem pretty advanced and optinnal), but it already works 100% nonetheless.
I have tested all the interlocks and safety mechanisms, they all work as they should. I have tried combining scenarios, there is no problem whatsoever.
Great stuff !

I have all that I wanted, including the dual speed dynamic brake (harder for emergency, more conservative for normal operation). I need to add an external resistor though as anything shorter than 2 sec. will trip the VFD in dynamic braking.

Looks like I only need to run the auto-tune now. I'm also curious about the A044 V/f characteristic curve 03Sensorless vector parameter, will search about that.

Man that VFD setup really is much nicer that the rest of the lathe is !


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## mksj (Sep 10, 2019)

Sensorless vector give much better motor control, in particular at lower motor speeds. It uses the motor windings/currents  to feedback position of the motor stator to the VFD so it can make continuous corrections which give tighter motor control. The default is what as known as V/Hz control which does not use feedback. Nice that you have it up and running, I recall your situation a number of years ago with a failed single phase motor. You do want to add an external braking resistor, they can be picked up inexpensively on eBay or electronics house, anything in the 50-75 ohms, 300-500W.


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## tino_ale (Sep 22, 2019)

Hi,

I got a 50ohm 500W resistor. But there is a problem...

I connected the resistor to terminals 1 and 3 on the upper connector line. Those are referred to RB and + terminals. I mistaken the first time and connected the load to RB and - terminals (positions 1 and 4) before I corrected my mistake.

Anyway either way the second I plug the machine my 30mA differential trips.

I isolated the resistor and measured 128 volts at the resistor body (ground as reference).

For the sake of the test I set b090 to 10% duty cycle and surprisingly the dynamic brake works ?!

I have tried connecting only one terminal at the time from the VFD to the resistor. Either RB or + terminal connected to the resistor alone produce the same effect which is instant trip of the differential.  I figure some current can leak from either terminal to the ground through the resistor casing.

I have opened the VFD to check of my first mistake did any visible damage but there is no damage to be seen.

With no resistor connected I read those AC voltages at the VFD terminals (ground as reference) :
RB : 34V
+1 : 129V
+ (connected to terminal +1 with a jumper) : 129V
- : 130V
Neutral is approx 1V floating
L1 is at 226V

The 3 motor terminals (while not running) are at 109V.

Do these readings look normal ?

Do I just have a poorly isolated resistor that needs replacing or do I have a bigger issue ?

I tried to measure the isolation of the resistor but I don’t have proper equipment. At 35 volts DC between either terminals and the resistor casing, I barely read 1mA at my multimeter. That is not much but I supposer more than it should!

Thanks


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## mksj (Sep 22, 2019)

If you are looking at leakage with a GFI (neutral wire), they do not work well with VFD's, if one is required then you need an expensive industrial type specifically for use with VFD's. Using a braking resistor should not change things, there should be no measurable resistance between the resistor casing and the leads unless it is defective. You should be ably to measure it with an ohm meter the resistance of either end of the resistor to the case and it should be in the megaohm range. It is DC on the buss not AC, the excess voltage is shunted through the resistor only with fast stopping. It is possible you damaged the resistor when it was connected to RB and - terminal as I believe this would be similar to placing the resistor between the high voltage DC buss and 0V.  When measuring AC you probably need a LowZ voltmeter to eliminate phantom voltages that can be induced in the AC wiring. The braking terminals modulate the voltage/current through the braking resister. The braking duty cycle is the %  varies on a number of different parameters.


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## tino_ale (Oct 5, 2019)

Hi,
I got a replacement 50 ohm resistor and everything is now working as it sould. The first one was either defective or damaged by me. No more differential trips, dynamic braking rocks !

I have set 3 seconds of braking time for normal operation and 1.5 seconds for emergency stop. I feel those are adequate.

As for acceleration time I have set 4 seconds. 3 seconds trips the overload protection at highest gear and highest Hz setting, I am using linear acceleration/deceleration. I’m sure some tuning would allow 3 sec acceleration though. It’s good enough though.

Thanks again ! I am relieved that I have not smoked something in my VFD.


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