PM-1236 motor issue

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:
 
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
 
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.
 
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
 
OK I checked the capacitors, they look ok.

That is the wiring sticker :
33589xy.jpg


And that is the actual wiring :
23r4knt.jpg


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)

33589xy.jpg


33589xy.jpg


23r4knt.jpg


23r4knt.jpg
 
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. :)
 
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.
 
It could be a bad winding causing the motor to run out of balance and with less output which could cause overheating.
 
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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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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