# Cunliffe Mill Electrical Problems



## Brain Coral (Jan 1, 2015)

Hello all,

First, I want to wish all of you a Happy New Year... 

I started a thread about this horizontal mill here...  http://www.hobby-machinist.com/showthread.php/23622-Cunliffe-Horizontal-Milling-Machine

... but decided to start a new thread here, concerning the electrical issues that I am having.

I recieved some replacement fuses from a kind friend in England over the Christmas holidays, to replace the 50 amp fuse that I burned out while trying to start the 2-speed motor on the mill.

Here are a few pics of the electrical panel to start with...

























Here's a pic of the mill...




This mill has a 2-speed motor, rated at 4hp (low speed) and 8hp (high speed). I have it powered with a 10hp RPC. I have no trouble at all in powering it at the low speed setting and can take a good cut with it. But when I try to power it up at high speed, the contactor cuts out. As well, I finally burnt out a 50amp fuse while trying to power it up at high speed after a few tries.

I have to go have lunch and will be back with more info...

Brian


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## Brain Coral (Jan 1, 2015)

Back again...  

There is a main power switch to the panel, that when engaged, locks the panel door closed...




So, once I recieved the new fuses and replaced the one that had burnt out, I decided to open the panel door (disconnected, of course... !!! ) and turn the switch to on with a couple of screw drivers, in order to see what went on upon turning the mill on.

When powering the mill up on the low speed (4hp) setting, the contactor to the right engages and stays engaged while the mill motor is running, and then drops back out once the stop button is pushed.

When attemting to power up the mill in the high speed setting (8hp) setting, the same contactor engages and then drops out on its own with a small puff of smoke coming from the contactor, shutting the motor down. The contactor on the left never engages at any time.

It was suggested that I try starting the mill at the low speed setting, and while it is still running, switch to the high speed setting. All this did, was the contactor let go and the motor shut back down.

I'm beginning to wonder if my 10hp RPC doesn't have quite enough juice to get the mill going at the 8hp setting. I have read recently, that if I have additional equipment of a lower hp running before I start the mill, it will boost the RPC's capacity. If this is true, how exactly is it done ?

At the present, I simply have a heavy gage wire and plug coming out of the RPC panel and a corresponding plug coming from the mill. I also have the same setup on my lathe, shaper, and vertical mill.

I found this link...

" If you have multiple pieces of equipment in your shop that are powered by three phase motors, all of the motors that are running at any one time will act as rotary phase converters, and will improve the quality of the power. Just wire them all including your idler through a single 3 phase sub panel, and power two legs of the sub panel with single phase 240 - the other leg will be powered by the phase converter and any other motors that you have idling. Breaker everything (including the idler) with the normal size breaker for the individual motors.  Then if you have one piece of equipment that draws a lot of current, you can start your phase converter, and then start another motor and let it idle in addition to the phase converter, while you use the high draw equipment. Needless to say you need to address all safety implications of having multiple machines powered up at one time. "

Is this correct ?  I have a lead on a 3-phase electrical panel for $100.00 with what appears to be several breakers. What should I be looking for in the way of the main breaker that feeds the panel ?

Brian


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## Ulma Doctor (Jan 1, 2015)

Hi Brian,
there is a big blue wire behind the contactor on the right that appears to be broken.
or is that a figment of my imagination?


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## Brain Coral (Jan 1, 2015)

Ulma Doctor said:


> Hi Brian,
> there is a big blue wire behind the contactor on the right that appears to be broken.
> or is that a figment of my imagination?



Hello Mike,

I just went down to have a look to be sure.... no, nothing is broken there...

About the 3-phase panel... does it work like the quote and will a 275amp panel work for me ?


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## den-den (Jan 1, 2015)

About the 3-phase panel... does it work like the quote and will a 275amp panel work for me ?

Yes, running motors will help the RPC and smooth out some fluctuations.
275 amps sounds like a lot, but there are more things to a panel in addition to amp capacity
  does it come with breakers?
  Can you get breakers that fit it in sizes appropriate for your needs?
  Does it have space for as many breakers as you need (plus a spare or two)?

I am not convinced that your problem with the high speed is related to your RPC capacity, although that may become a problem if you need the full 8hp of the mill.  You should go through the wiring diagram and verify the controls work before assuming the problem is the RPC.


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## Brain Coral (Jan 1, 2015)

Hello den-den,

Yes, the panel has lots of 3-phase breakers...

Unfortunately, I don't have a wiring diagram and really don't know where to begin to trouble-shoot it...

Brian


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## Ulma Doctor (Jan 1, 2015)

Brain Coral said:


> Hello Mike,
> 
> I just went down to have a look to be sure.... no, nothing is broken there...
> 
> About the 3-phase panel... does it work like the quote and will a 275amp panel work for me ?




i saw a blue wire that was next to one of the contactor coils that looked suspicious , i'm glad it was only in my imagination.

the three phase panel idea is true, 275 would work out great! but it is overkill
 by running more motors in the circuit, the total circuit balance is harder to distort.it becomes a better autotransformer
in other words- you short circuit a motor every time you fire it off, which distorts circuit balance- with a RPC you'll have 2 legs that are supplied and 1 leg that is generated through induction as long as single phase power is not interrupted to the RPC.
the RPC will supply 3 phases of power in relation to each other but the generated leg will not shoulder the load in the same manner as the legs connected to it's input. Added motors help smooth out the balance differences between all motors in the system.


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## Ulma Doctor (Jan 1, 2015)

at this point i'm suspect of the speed selector switch & wiring.
i can't rule out the high speed motor windings at this point, 
but as stated before with some effort we can get to the bottom of it!:detective:


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## Brain Coral (Jan 1, 2015)

Hello Mike,

Thanks for the input. The holidays have been much busier than I would have imagined and there hasn't been much time for the shop. I do intend on moving the motor out of the base, to see how things are wired and will post pics and text as to what I find.

Would that be a good start, or should I start somewhere else first É

Oops... the darned shift and control keys are close to each other and when I hit them both in a certain way, I begin to speak Spanish... 

Brian


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## Ulma Doctor (Jan 1, 2015)

i think yanking the motor or at least gaining access to the leads for testing the windings would be a great start.
if we can isolate the motor and test the high speed windings, we can eliminate the motor as the cause.

as a side note, i can't rule out the possibility of the last owner not having the high speed switch wired correctly, but that will be another discussion.


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## Brain Coral (Jan 1, 2015)

Ok, thanks Mike... 

I'll get to that maybe tomorrow afternoon.

Brian


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## Brain Coral (Jan 4, 2015)

I'm back again... 

I finally had a chance to slide the main mill motor out of the base to get at the nameplate as well as the wiring. The pics aren't great, but might be clear enough to glean some information.













It appears that the motor has been rewound to 208v/ 60 cycles. There are 6 wires coming out of the motor and the connections look straightforward. Maybe you experts can tell if it is wired properly.

I checked the amperages of the RPC and this is what I read...

     L1   Inrush...  140a
           At Idle...       8a

    L2    Inrush...  130a
           At Idle...     8a

I then checked the amperages of the RPC with the mill motor running...

    L1                                              Inrush...  65a
           Mill running without clutch engaged...  17a
                       Inrush with clutch engaged...  22a
                                             Mill running...  17a

L2 was within 1 amp of L1.

I must go snowblow my driveway and will check back in a little while...

Brian


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## den-den (Jan 4, 2015)

It appears that the motor has been rewound to 208v/ 60 cycles. There are  6 wires coming out of the motor and the connections look  straightforward. Maybe you experts can tell if it is wired properly.

Do these six wires go from the motor to the starter panel and if so, do three connect to one of the contactors and the other three connect to the other contactor?


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## Brain Coral (Jan 4, 2015)

Hello den-den,

At this point, I don't have the answer to that. Inside the motor cavity are numerous armoured cables and "T" junctions to supply the other two motors as well as a light. There isn't much room, but I will try and see where the wires go to.

The contactor on the left ( the one that doesn't engage ) has three white wires coming to the bottom of the contactor and there aren't any white wires that are wired into any of the motor leads. In addition, these white wires are of braided wire, while all of the original wiring inside the panel is solid copper, so I assume that this may have been done when the two motors were rewound.

I removed the flash guards on the contactors and found some wear and slight pitting on the contacts, but nothing jumped out at me. I removed each hold-down spring and cleaned up the copper contact areas while I was at it.

Canadian  commercial 3-phase voltages are typically 208v from what I was told. Both of the motors on the mill have been rewound to 208v. Also, the idler motor is a Leeson motor with a 208v rating. My RPC panel was bought out of the U.S.A. and is producing approximately 240v. Is this a concern in the present situation ?

Brian


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## Ulma Doctor (Jan 4, 2015)

Brain Coral said:


> The contactor on the left ( the one that doesn't engage ) has three white wires coming to the bottom of the contactor and there aren't any white wires that are wired into any of the motor leads. In addition, these white wires are of braided wire, while all of the original wiring inside the panel is solid copper, so I assume that this may have been done when the two motors were rewound.
> 
> I removed the flash guards on the contactors and found some wear and slight pitting on the contacts, but nothing jumped out at me. I removed each hold-down spring and cleaned up the copper contact areas while I was at it.
> 
> ...



Hi Brian,
i'm thinking the contactor on the left is the pump motor contactor because the current limit on the 4amp Overload relay is for a small motor- it's probably not going to pull in unless you actuate the pump switch.

slight pitting is completely normal for electrical contacts- no worries there.

US 3 phase Wye Transformed power is also stepped down to 208vac, most of my grocery stores are supplied 208 vac. 
using 240 from the RPC most likely is not going to hurt you in this case. electrical tolerance is usually 10%
240-24=216 or (8 volts beyond tolerance for a milling machine no big deal) i routinely run equipment rated 208 on my 240 supplied RPC.
you'll have the added bonus of total circuit amp reduction, a motor at 240vac will pull less amps than the same motor on 208vac due to the increased voltage
Ohms Law states that amperage is inversely proportional to voltage- 
When volts are higher, the amperage required to do the same work is lower and vise verse, when the resistance is constant.

the blue wires appear to have been added when the 208v rewind was done.

the last picture is really dark for the motor connections , can you take a picture with a flash or a flashlight so i can better see how it's wired?
Cheers,
mike


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## Ulma Doctor (Jan 4, 2015)

as i'm racking my brain on this-
 i started another line of questioning in my head,i'm writing out loud so bear with me.

did the spindle turn in the correct direction when you originally turned on the mill in the high speed position
(when it sounded bad and attempted to run)?


let me know if i'm starting to confuse you, if so we'll take one thing at a time.

 were going to compare some things in a minute...


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## Brain Coral (Jan 4, 2015)

Hello Mike,

Well, that is all good news. I don't have the base filled with coolant, but I might try to start the pump for just a few seconds and see if the left contactor pulls in.

What do you think the next step might be ?

Brian


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## Brain Coral (Jan 4, 2015)

Oh, there you are... 

No confusion here, Mike...   at least not at the moment... 

Yes, the spindle turned in the same direction as when the low speed setting was engaged. On this particular mill, spindle direction can be reversed mechanically through a gear lever.

When the high speed setting was turned on, the motor seemed to take an inordinate amount of time to come up to speed, compared to the almost instantaneous low speed setting.

I did manage to get the high speed setting to run up just the one time and also engaged the clutch and had the spindle turning. It only shut down because I shut it down to change the speed selector and try it in the other settings.

Brian


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## Brain Coral (Jan 4, 2015)

Mike, here's something that I looked at this evening...

C and A in the RPC panel are the incoming single phase lines and B is the "wild leg". Inside the idler motor, I had the "wild leg" hooked up to L2, so to speak. I have since changed that to L3. Then, where the 3-phase power comes out of the RPC to a female plug, I made sure that the "wild leg" goes to L3 in the mill panel terminal.

Before I did this, the "wild leg" went to L2 in the idler motor. Would this have had any affect on the issue ?

Brian


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## Ulma Doctor (Jan 4, 2015)

Brain Coral said:


> Hello Mike,
> 
> Well, that is all good news. I don't have the base filled with coolant, but I might try to start the pump for just a few seconds and see if the left contactor pulls in.
> 
> ...




Hey Brian,
you could try it and see, it won't hurt the pump for a quick check.
i'm not telling you to do this-
 but, in the field if i want to know if a machines' problem is control oriented or motor oriented i take one simple step after exposing the contactor panel, 
i take an insulated screwdriver and physically actuate the contactor with the screwdriver.
if the motor runs, i (or you) then can deduce the control circuit is at fault.
in machinery, 3 phase motor circuits are(generally) supplied with main voltage and broken by means of contactors that are controlled by the control circuit. sometimes the controll circuit is the same voltage as main voltage(as in your case) , most times control voltage is lower than main voltage in machines for US Industry .


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## Ulma Doctor (Jan 4, 2015)

Brain Coral said:


> Mike, here's something that I looked at this evening...
> 
> C and A in the RPC panel are the incoming single phase lines and B is the "wild leg". Inside the idler motor, I had the "wild leg" hooked up to L2, so to speak. I have since changed that to L3. Then, where the 3-phase power comes out of the RPC to a female plug, I made sure that the "wild leg" goes to L3 in the mill panel terminal.
> 
> ...



anytime you change 2 of the 3 hot wires or the 2 supply wires place in relation to each other, you will reverse the rotation of the RPC and any motor hooked up to the RPC.


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## Brain Coral (Jan 4, 2015)

Ok, I see... I did change the location of 2 wires in the plug, previously, so that the mill motor turned in the proper direction in order for the oil pump to work. But would the "wild leg" being hooked up to L2 in the idler have had any affect on the present circumstances ?

Brian


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## Ulma Doctor (Jan 4, 2015)

not likely the problem.
sometimes transformers don't like the generated leg- you don't appear to have a transformer.
 if your contactors are pulling in and aren't buzzing loud i wouldn't be concerned.)


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## Brain Coral (Jan 4, 2015)

Ok, so just now, I went down to the shop, first... to exchange L1 and L2 inside the idler motor to get the proper rotation again... Check... all is well...

I then had the RPC going and tried the pump switch. It sounded like it started, but did not engage the left motor contactor. Then, with the main motor hanging out of the back, but not engaged with the pulleys, I started the main motor in the low speed setting and then engaged the "rapid traverse" motor and, voila, the left motor contactor engages each time I push the button...

Brian


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## Ulma Doctor (Jan 4, 2015)

Duh:headshot:,
i made no consideration for rapid traverse...
we are both learning things here)


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## Brain Coral (Jan 4, 2015)

Hello Mike,

The rapid traverse motor is a sizable motor and it didn't occur to me either at first... I was just running out of motors to try...


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## Ulma Doctor (Jan 4, 2015)

Brain Coral said:


> Hello Mike,
> 
> The rapid traverse motor is a sizable motor and it didn't occur to me either at first... I was just running out of motors to try...





:thumbsup2:
sometimes motors appear big but are deceivingly low horsepower.


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## Brain Coral (Jan 4, 2015)

So, are there any plausible reasons that come to mind that might be causing the motor contactor to "fall out" in the high speed setting ?

Brian


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## Ulma Doctor (Jan 4, 2015)

i'm going out on a limb and saying what a possibilities could be-

a wire somehow got reversed or out of place in the high speed switch or it's connection to the motor.

a faulty overload for the high speed motor control

control wiring issue unknown


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## Brain Coral (Jan 4, 2015)

Well Mike, at least we are getting somewhere. Slowly, but surely, we are eliminating some of the possibilities and learning more about the electrical system. I should keep careful notes for the next guy down the line... 

I might try taking some of the equipment out of the way, carefully photographing and documenting wiring, etc. to have better access to the switching. If there is any measurements that I should take, as in voltages, amperages, ohms, let me know.

Brian


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## Ulma Doctor (Jan 4, 2015)

working without a diagram is like riding a unicycle on a basketball in long distance troubleshooting!:jester:


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## Brain Coral (Jan 4, 2015)

I agree... I wish that I had one. There likely was one on the inside of the cabinet door, but it has gone like the powdered rubber gasket door seal...

Unless I have something specific to look for, I will do some careful investigating. I might not be up on electrical problems, but I am careful and meticulous and will not go beyond what I can put back together.

I am off to bed for an early start to my week. Thanks for all of your help, Mike 

Brian


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## Ulma Doctor (Jan 4, 2015)

i'll stick with you Brian, there are things that would take me seconds to figure out if i were there. but i'm happy to help the hard way )!!!
i'm still thinking wye start/run low/, delta-high speed kinda like this

http://apps.motorboss.com/connections/3226.pdf

we can check out the motor windings, test switches, test wiring, test overload relays and contactor coils whatever is necessary!

Where would you like to start? 
 i'd start with the high speed overload relay and go from there . ohm check pole for pole to see if all poles have continuity.
test overload circuit interrupt terminals - they should be normally closed- if they are open the contactor may drop out.
if the overload has removeable heaters remove them and ohm test them too!

no worries we'll get it tickin' soon enough.
we can get into other things later

no need to say thanks yet, 
you can say thanks to all who help out getting her running- when she's running again!!!!
cheers, and good night sir
m)


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## Brain Coral (Jan 10, 2015)

Hello again Mike 

I haven't checked in on this thread for a few days and didn't see your reply until now. I have been working on a couple of kitchen cabinets for a client and have all of my metalworking machinery all covered up with tarps.

I've tried starting the mill at high speed a couple more times, after cleaning the contactors, but it drops the contactor out every time. I did notice, with the motor hanging out of the back, that it "growls" a little when starting up at high speed, but not at low speed.

Looking at the pics of the panel, where would I find the high speed overload relay and also the overload circuit interrupt terminals ?

Thanks... 

Brian


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## Ulma Doctor (Jan 10, 2015)

Hi Brian,
i think the OL relay is the larger black box at the bottom of the control panel.
this item either comes apart where it sits, but may have to be removed to disassemble.
try to do it the easy way first, in the machine...
there is a most likely 3 coils or heaters as they are called, inside of the OL relay.
visual inspection can often see any suspect overheating or open coils
an ohm test would confirm their serviceability. you would test the interrupt terminals on the same OL relay sometimes marked #'s 95 and 96

in the off chance the OL relay doesn't have removable heaters or is found faulty, replacement would be necessary.


mike)


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## Brain Coral (Jan 10, 2015)

Hello Mike,

This is a start... I think that this is what you were looking for...







This is the method that I used to test it. Is this correct ?







I don't have a handle on all of the jargon and I don't understand the interrupt relays... ?

I have company coming for supper, so I'll have to leave this until tomorrow morning...

Brian


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## Ulma Doctor (Jan 10, 2015)

Brain Coral said:


> Hello Mike,
> This is a start... I think that this is what you were looking for...
> This is the method that I used to test it. Is this correct ?
> 
> ...



Hi Brian,
that is an OL relay, yes sir!!!
I don't like the looks of the heater coil on the right side, if you look at the  heater coil the inner coil appears to be touching the outer coil or are very close to touching and could be a factor in the shut down condition.:thinking:

(i'm assuming you have already disconnected power to the mill)
I am curious also to look inside the little box situated below this OL relay, the one labeled " Danger live Terminals".
if you disconnect the power from the milling machine to the RPC you won't be in danger to remove the cover mentioned above that conceals the guts of the larger black box. there appears to be a dial or knob missing- that throws up a red flag for me...

Yes Brian, you will test each terminal exactly as pictured on  the Rx1 setting(lowest ohm setting for low resistance circuits). you should read very little resistance or no resistance dependent on the sensitivity of your meter on each set of terminals.
the interrupt circuit is the 2 smaller terminals pictured on the left side of the OL relay.
by putting a meter leads on both of the smaller stacked screw terminals and setting the Ohm meter to Rx1(lowest setting) you can test the interrupt. the interrupt should be a normally closed switch thus there should be little or no resistance measured dependent on the sensitivity of the meter.
if this switch should happen to be open, it would need repair or replacement- it is not functioning correctly.

i'll try not to use too many technical electricalisms , let me know if i'm confusing you and i'll take it down a notch.
i make the constant mistake of thinking that others know what i know,:banghead:
(not always a good thing- there are a lot smarter people than I)
mike)


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## Brain Coral (Jan 11, 2015)

Hello Mike 

I'm back with a brief update. I get a Zero reading on all terminals, including the interrupt terminals. I decided to remove the other relay to compare the two and to check if the readings were the same. I realize that the other relay has nothing to do with the main motor contactor, but I just wanted to have a look while I was at it.

I adjusted the spring in all three heaters so that there is no contact at any point. The other two heaters had very close contact, if not actually touching at a couple of points in the spiral when closing the contact.

Before....




After...




Here is a pic of the other relay...




As far as the lower " Danger Live Terminals" box is concerned, there doesn't seem to be anything amiss. There is a screw missing that attaches the front cover... the bakelite housing is broken away at that corner for some reason... The spot that appears to be missing a knob, engages the lever on the door of the panel and is simply an On/Off safety switch. When turned to the On position, the lever is locked onto a cam that won't allow the door to open. I have cheated it for these pics and turned the switch to the On position with a couple of screwdrivers...  NO POWER WHATSOEVER  !!!  to the mill, of course...



















Since I've "adjusted" the heaters, should I go ahead, reinstall and try the high speed again, or should we troubleshoot some more? What kind of damage will there be to the motor with repeated attempts at starting it with one phase seeming to be missing ?

Brian


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## Ulma Doctor (Jan 11, 2015)

Hi Brian,
The repaired OL looks good now after bending the coil.:thumbsup2:

The Danger Live box is simply the on off switch, I see now...i was a little perplexed by the box.


After making the repair to the OL heater, i'd re-install and go for a test run.
you'll want to set the OL to it's highest setting by pushing the indicator lever to the right(i believe it was 14Amps or 16A if memory serves) and try to fire it up once again.

Damaged windings could occur as a result of trying to start the motor with only single phase supplied, if the single phase condition was to last a long time without a breaker kicking out. 
The amps would likely rise in the single phase circuit in attempting to start the motor and kick your breaker.
most likely you won't cause any more significant damage than has already been done, if there already was an existent winding issue.
just don't let the motor try to start in a stall condition for more than a couple seconds without rotor movement , you'll be OK


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## Brain Coral (Jan 11, 2015)

Hello Mike,

Sounds good... I'll re-install the relays and give it a go in the morning. I'm kicking back, after a good supper and a couple of beers... 

Brian


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## Ulma Doctor (Jan 11, 2015)

just another anomaly i saw when re-looking at the pictures,
 i noticed on the second OL you removed as a comparison unit, the right side heater on that OL seems to have had some trauma to it as well. it is visibly "bluer" than the other 2 heaters. it may be indicative of the mills past problems.
if the heater still functions that's great, 
but, we can no longer trust that the questionable OL heaters in either OL relay will operate with the same resistance as the other heaters. 
When heaters overheat, their chemistry changes ever so slightly.

 they become more resistant to electrical flow, which in turn creates heat. 
the heat in the circuit increases the amperage necessary to complete the work of the resistant circuit.
After too many overheats, the heaters become extremely resistant to electrical flow and heat up even more as a result, ad infinitum, all the way to the point of failure.


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## Ulma Doctor (Jan 11, 2015)

Brain Coral said:


> Hello Mike,
> 
> Sounds good... I'll re-install the relays and give it a go in the morning. I'm kicking back, after a good supper and a couple of beers...
> 
> Brian




Sounds good to me too!!
Enjoy the relaxation!!!
I think I'll join you in a long distance beer!!!
:drinkingbeer:
Cheers!
mike)


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## Brain Coral (Jan 11, 2015)

Cheers... Mike :drink2:

Ummmmm... that's me on the right... 

Brian


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## Brain Coral (Jan 12, 2015)

Back again... 

I re-installed the relays and did a test run, but it's still acting the same. I gave it some thought and it occured to me that if the contactor works as it should and the motor fires right up in the Low speed setting, then the relay must be working properly, so I'm leaning towards the switch itself... perhaps one of the contacts in the switch is worn out or burnt. I haven't ruled out the possibility that there might be something wrong with the windings, but I think that I should have a good look at the switch first.

Brian


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## Ulma Doctor (Jan 12, 2015)

I concur, if it still acts the same we didn't find the problem.

we may have something mis-wired in the delta circuit (high speed) or a malfunctioning switch.

i really don't think you have a winding problem, 
just to start the motor in the wye configuration(low speed), 
motor terminals U1,V1,W1 are all connected together(shorted),
 power is fed directly to motor terminals U2,V2,W2 .
 if any one of the low speed windings were burned out, you would get the single phase condition of loud noise and extreme hard starting. we don't have that condition.
there are no additional windings to the motor we only have 3 sets.
 all windings were utilized to run the motor in low speed
through osmosis we determine wye windings are satisfactory. most likely the motor is ok
I'll make that assumption for sake of argument at this point.

what does change is how the motor is wired to run in the Delta configuration
motor terminals U1,V1,W1, are supplied line voltage and U2,V2,W2 are connected (shorted) together.

There is another way of wiring the motor too,

for low speed operation:
Line 1(L1) is connected to motor terminal T1
L2 is connected to motor terminal T2
L3 is connected to motor terminal T3
Motor terminals T4,T5,T6 are left open(not connected to the motor circuit- allows only low speed operation on 1/2 of windings)

for high speed operation
L1 connects to T6
L2 connects to T4
L3 connects to T5
motor terminals T1,T2,T3 are shorted(connected together)- allows operation of high speed only in Delta configuration- all windings are being used.

all this as food for thought.

there may be others that may be able to add additional inspiration or if nothing else a tip or 2.


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## mikedoon (May 23, 2015)

Hey brian a friend of mine asked me to rewire his cunliffe mill a few months back as someone had made an attempt to do it a few years back and never finished it they just ripped out everything as it stands I have the power traverse and coolant pump running but I'm having problems with the spindle motor also from what I gather from testing the motor it has two separate windings for high and low speed if you check the high low changeover switch and take a photo of the connections I can compare it for you as this was the only part of the wiring left intact on the machine


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## Brain Coral (May 24, 2015)

Hello Mike 

If the mill that you are working on is the same as mine, you'll agree that getting a good pic of the switch wiring is difficult, to say the least.... I am quite sick with the flue at the moment, but I will try to get down to the shop and take a picture this afternoon...

Brian


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## mikedoon (May 24, 2015)

Brain Coral said:


> Hello Mike
> 
> If the mill that you are working on is the same as mine, you'll agree that getting a good pic of the switch wiring is difficult, to say the least.... I am quite sick with the flue at the moment, but I will try to get down to the shop and take a picture this afternoon...
> 
> Brian


I found the easiest way is to just rip the switch out the end of the knob on the switch health a hole with a flat head screw undo this and remove the knob and remove the screws on the lebel plate behind this is two more countersunk screws which have nuts on the far end of the switch once these are undone the switch will come out takes approx 3 mins have you managed to get both speeds to run on the mill yet


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## Brain Coral (May 24, 2015)

Hello Mike 

You need to practice some punctuation, dude...  

I was able to power up the high speed setting of the motor only briefly, then the contactor would kick out. At testing, the amperage readings of the inrush, reached nearly 150 amps...  

I didn't feel well enough to tinker with the switch today. I'll have a go at it in a couple of days.

Cheers... 

Brian


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## mikedoon (May 25, 2015)

Ya I know my English writing is terrible. I wouldn't worry too much about inrush current a motor can draw up to ten times its full load current on start up. Can I ask what horsepower your convertor is. the problem I am having with my buddy's one is that when I try and start the spindle motor the voltage collapses and the idle motor in the convertor stops briefly. He has a 15hp convertor

Regards
mike


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## Brain Coral (May 25, 2015)

Ahhhhhh..... that's much easier to read... thanks buddy  

My RPC is a 10hp unit and has no problem in starting the mill in the low speed setting.  I don't believe that the issue is the RPC, at least on my mill. I am wondering if one of the contacts on the switch is bad and not allowing all 3 phases to get to the motor on the high speed setting. Right now, I have the mill just about completely torn down, trying to repair the feed gears for the knee, so the electrical issue has taken a back burner for now.

Brian


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## mikedoon (May 25, 2015)

Brain Coral said:


> Ahhhhhh..... that's much easier to read... thanks buddy
> 
> My RPC is a 10hp unit and has no problem in starting the mill in the low speed setting.  I don't believe that the issue is the RPC, at least on my mill. I am wondering if one of the contacts on the switch is bad and not allowing all 3 phases to get to the motor on the high speed setting. Right now, I have the mill just about completely torn down, trying to repair the feed gears for the knee, so the electrical issue has taken a back burner for now.
> 
> Brian


From what I can gather from testing my mates one it has two separate sets of windings in the motor one for high and one for low. Have you tried disconnecting the motor and hitting the start button this will verify your control wiring is OK if the contactor stays pulled in. After that I would do resistance checks on the motor to check of it is OK I could talk you through this if you wanted and compare readings. I'm thinking of connecting my mates one to a diesel generator to rule out the RPC at least I know that that will hammer the power in and will show any problems I can just check for smoke ha.


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## Brain Coral (May 26, 2015)

Hello Mike 

No, I hadn't even thought of doing that to try the start button with the motor disconnected.  I'll give that a try on the weekend, as this week, I'm working outdoors as a carpenter in 30* heat and battling clouds of blackflies, so by the time I get home I'm beat...

Brian


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## psychodelicdan (Dec 8, 2018)

Sorry this one gets a bit long. Maybe it will be of some help to someone.
Was this trouble ever solved? This reminds me of the troubles with the early Tiawan mill at work. it's old ,has no paperwork ect. Most if the low voltage controls have failed and Ben disconnected. Some by me. I switched wiring so the low speed worked. Eventually the motor starter failed. I switch the high speed for the low speed and it seemed to run fine. 
Then the motor started to smoke and shut down. Turn it on run for 15 20 seconds puff smoke and shut down. 
Sent the motor in for repair and was told all was good with no sign of burning to cause the smoke. Reinstalled it same problem. 
Brought in a service tech that said it was ok good to go.it wasn't.
I then ignored the mill for a year or two.
One day with a fresh mind I went at it and realised that I had both the low speed windings AND the high speed windings wired together. I disconnected the high speed wires and now it runs fine on low. With some new parts and knowledge I would think I could now get the high speed to run.

Sent from my XT1254 using Tapatalk


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