Need help with unmarked wires on 220 volt motor

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  #1  
Old 03-03-07, 12:11 AM
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Exclamation Need help with unmarked wires on 220 volt motor

I have a paper folding machine which has two motors both identical. One powers the machine itself and the other a vacuum pump. The machine was made aprox. 1950 but still works (built like a tank, new ones are basically still the same today but with more automation & electronics). I acquired it from another print shop closing operation. The machine had power to it and was running, but when I came to pick it up they had already removed the wire nuts from the motor driving the vacuum pump. The other motors is attached to the machine and is still connected. My problem is all 4 wires on the vacuum pump motor are all black and the labels (t1, t2, t3 and t4) have all fallen off due to age. The plate on the motor shows that t2 & t3 should be connected together and t1 and t4 to power wires. I checked continuity using the other motor which still has labels in tack. Here is what I got on it:
t1 & t2 continuity
t1 & t3 no
t1 & t4 no
t2 & t3 no
t2 & t4 no
t3 & t4 continuity

I determined on the other motor which to sets of wires have continuity, but I don't know which is t1/t2 and t3/t4. I know t2 and t3 should be wired together, but if I connect t1/t4 together instead of t2/t3 will it work or short???? I could really use some help on this one.

Thanks
John
 
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  #2  
Old 03-03-07, 02:07 AM
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There's too many variables in motor wiring. You need to take it to a motor shop.
t1 & t2 maybe a thermal overload.
t3 & t4 maybe a starting switch that is normally closed.
Or the other way around.

Continuity is just basic you would also need to match the resistances with a good meter.

Then if your able to identify the coil wires you also need to identify the proper phasing of the coils.
 
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Old 03-03-07, 05:30 AM
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is this a reversible (direction) motor? If so, the only thing that will happen if you connect it back wards is the motor will run back wards.
 
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Old 03-03-07, 06:59 AM
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The motor probably has standard wiring for a dual voltage non reversible motor since it has only 4 leads.

Measure the resistance across each set of wires. One should be different. If it doesn't show "0", then the lower of the 2 is the one with the start winding in parallel with it. If this is what you see, try the following:

Label 1 wire as T1, really doesn't matter which. Label the wire with continuity as T2. Connect one of the other wires to T2. Get a 9 volt battery and connect it to T1 and the wire that's left. Then get a compass and move it around the outside of the motor. The needle should reverse as you move it around the outside (keep the same edge of the compass against the motor). If it doesn't, reverse the 2 unmarked wires. When it compass reverses as you move it around, mark the wire connected to T2 as T3 and the other as T4.

You will need to verify that T1 and T3 connected together and T2 and T4 connected together and connected to the battery doesn't reverse the compass before you connect T2 and T3 together and connect T1 and T4 to line voltage
 
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Old 03-03-07, 08:58 AM
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Take it to a motor sop and have them ring it out .
 
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Old 03-03-07, 11:01 AM
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unk: The motor probably has standard wiring for a dual voltage non reversible motor since it has only 4 leads.
====================================

there is also a 4 lead reversible single voltage motor but I will accept this is more than likely a dual voltage non-reversable since L1 and L2 are tied to a single lead and the 2 remaining leads are tied together. This would be a typical hook-up for the higher voltage of a dual voltage motor. A single voltage reversible would have L1 or L2 connected to 2 leads in either rotational configuration.
=================

How about we do this:

give us all the info on the motor.
give us all the combinations possible listed on the plate

give us the voltage it was connected to (if known) and the voltage you are intending on connecting it to.

(if the voltages are different, you would have to change the connections on the other motor as well lest yoou will let all the magic smoke out. The last shop I talked with charged no less than $500 to put the smoke back in)
 
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Old 03-03-07, 11:10 AM
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Talking

Here is a little more infor for itsunclebill. The motor diagram does also show wiring it for 110 use with t1/t3 connected and t2/t4 connected. I don't know if this motor is reversible or not. Here is the plate specs on the motor if this helps (both motors identical spes.) :

Leland Motor
Type RA
FR 4B66
HP 3/4
V 115/230
Amps 11.6/5.8
RPM 1725
CY 60
PH 1
Rise 40 C
Duty CONT
Ref 11868 DR 10779


If I do take the 50/50 chance at which one is t2/t3 and I have wrong (backwards) will the motor run in reverse or billow out plumes of black smoke?

Thanks,
John
 
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Old 03-03-07, 11:34 AM
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Bill was correct about the dual voltage.
and it is non-reversible( ok bill, you win this one. you were right)

You need to answer the voltage question I asked though. Regardless is you hook it up correctly or not depends on what voltage it was hooked to and what you are intending on utilizing.

if you hook up the wrong voltage, you're going to smoke it.
 
  #9  
Old 03-03-07, 12:32 PM
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The intent is for it to be run one single phase 220. The other motor on the machine is already wired correctly and it's wires are labeled. t2/t3 are together on that motor. Power comes to juction box on the machine which splits off to the two motors with a couple of heavy duty switches in there also for each motor. i don't know why the person that disconnected power from the motor even touched t2/t3, would have saved me all of this if they had just left those two alone. The main power plug is an old stlye dryer plug with 3 wires, ground, hot, neutral.

Hope this helps.
 
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Old 03-03-07, 08:40 PM
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I'd spend the time to verify the polarity on the coils. Some motors (very few, though) will run just fine with one coil backwards - except they run half speed. The majority will either sit and hum or won't start turning rapidly. Neither of these conditions is going to help 50-60 year old insulation on the motor windings and may indeed let some or all the smoke out.

The insulating varnishs used on many old motors doesn't have the flexability the newer ones do and may have developed cracks over the years. Wiring the motor up wrong may cause a spark to jump through one of these cracks or heat the stuff up enough it looses the ability to hold the wires apart. If the motor is old enough it will have a fabric insulation on the coils and this stuff has no tolerance for any abuse.

I suppose the other issue here is that a motor that old could possibly be a repulsion start - induction run type motor with a wound rotor. Wiring the coils wrong could damage the rotor also if this is the case. I don't think you could find a shop that would even attempt winding that. The last motor I wound was over 25 years ago and repairing this type motor was cost prohibitive even then. But, I digress.

Follow the instructions I gave you and you should be fine.
 
  #11  
Old 03-04-07, 01:29 AM
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tsunclebill,
Okay I will and thanks so much for your help. I let you know the outcome.
John
 
  #12  
Old 03-17-07, 03:46 PM
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I would measure on the working motor.
Is it about 50% voltage on between t1 and t2? If not the following is of no interest.

Measure and find the 2 circuits, and connect them in series.
(The vacum pump shold run with nearly no resistance the first few turns.)
So then hook up a suitable resistor in series (eg a hair dryer on at 500-750Watts) and connect to the voltage of the hair dryer e.g. 120V. (max 10sec.)
If the motor spins a few turns you have moast likely done it right, if not (just humming) reverse the wires of one (and only one) of the windings, and test again. No it shold work.

dsk
 

Last edited by d_s_k; 03-17-07 at 04:07 PM.
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