Never seen a motor wired this way

[StengthThroughUnity]

I have several 3 phase 6 wire motors without nameplates from an industrial freezer. The supply voltage is 208. So I wired a couple motors in Delta for low voltage L1-T1-T6, L2-T2-T4, and L3-T3-T5 only to find the motors overheat and fail. The same thing happened when I tried wiring them in Wye L1-T1, L2-T2, L3-T3, and T4-T5-T6 over heat and fail. The only motor that works and was already on the freezer is wired L1-T4, L2-T5, L3-T6, and T1-T2-T3. This appears to be Wye wired backwards! How is this motor working when my other motors wired in Wye failed?

 

[hbiss]

Did you ever determine what windings are connected to what leads with an ohm meter? I wouldn't assume anything, especially after burning up two motors already.

-Hal

 

[Hv&Lv]

I have found motor data plates wrong and terminal wiring wrong.
Never found both wrong on the same motor though

 

[kwired]

They might be two speed, two winding motors. If so you only supply T1, T2, T3 for one speed or T4, T5, T6 for the other speed and cap the unused leads, or connect to two contactors or drum switch to only supply one winding at a time to select speed.

 

[hillbilly1]

I have found motor data plates wrong and terminal wiring wrong.
Never found both wrong on the same motor though

I had a small transformer that the factory put an incorrect wiring connection label on, it didn't show the windings, all it gave was the wire numbers. Hooked it up, let the magic smoke out. The supply house tried to say it was wired wrong, but the manufacture admitted, no, they screwed up and labeled it wrong. Don't know how many they sent out that way, but they replaced it, and it came with different wiring instructions!

 

[hbiss]

The only motor that works and was already on the freezer is wired L1-T4, L2-T5, L3-T6, and T1-T2-T3.

If you saw how that motor was connected and was working why did you connect the others differently? Did you take current readings on each of the phases of the motors that failed to see if they were all equal or unusually high?

-Hal

 

[StengthThroughUnity]

If you saw how that motor was connected and was working why did you connect the others differently? Did you take current readings on each of the phases of the motors that failed to see if they were all equal or unusually high?

-Hal

The motors don't have data plates with wiring information like most I've seen before. But the terminal windings are labeled coming out of the motor. I never checked the existing motor wiring because I thought terminal numbers were standardized and wired it up like I would any other conventional motor for the voltage.

They might be two speed, two winding motors. If so you only supply T1, T2, T3 for one speed or T4, T5, T6 for the other speed and cap the unused leads, or connect to two contactors or drum switch to only supply one winding at a time to select speed.

I don't think these motors are that fancy but how would I determine if these motors are 6 wire 2 speeds?

Did you ever determine what windings are connected to what leads with an ohm meter? I wouldn't assume anything, especially after burning up two motors already.

-Hal

Yeah lesson learned I think these motors have been rewound. I'll ohm out the windings Monday when I get back to work, and have a talk with the company that rebuilds our motors. Does anyone know the procedure using a battery to determine which end of a winding is which?

 

[hbiss]

Does anyone know the procedure using a battery to determine which end of a winding is which?

Never heard of that. Thinking about it, if you put an AC voltage (maybe 24V) on one winding then, with a 2 ch scope, look at the phasing of that voltage and compare it to the induced voltage on each of the other two you could quickly see which way they go. In phase or 180 deg out.

-Hal

 

[StengthThroughUnity]

Never heard of that. Thinking about it, if you put an AC voltage (maybe 24V) on one winding then, with a 2 ch scope, look at the phasing of that voltage and compare it to the induced voltage on each of the other two you could quickly see which way they go. In phase or 180 deg out.

-Hal

Unfortunately I don't have an oscilloscope yet.

What I don't understand is the only motor working without issue is wired for wye with only 208 volts on the supply? There are no switching contactors in the cabinet for a wye start Delta run type of motor either. Shouldn't this motor have burnt up a long time ago? Just like the ones I wired in wye did.

 

[hbiss]

Maybe the others were no good. How long before they crapped out? Did they run at all?

-Hal

 

[synchro]

Wiring them in Wye L1-T1, L2-T2, L3-T3, and T4-T5-T6, vs. L1-T4, L2-T5, L3-T6, and T1-T2-T3 (what you mentioned was Wye wired backwards) would change the voltage across each of the three windings by 180 degrees. Therefore these two different connections would behave identically because the relative phase between any two windings is the same in either case. Just the absolute phase going to each winding was changed 180 degrees, which certainly doesn't matter for an induction motor which is always slipping phase anyway.

 

[kwired]

Measure continuity between leads.

If you have three pairs with continuity then each pair is one winding. connect them in wye configuration first would be the thing to do as it puts less volts across each coil than connecting them in delta does. Then see how it runs.

If you have two sets of three with continuity between them, then they are two sets of wye connected coils. Good chance this could be the two speed setup if you have this, only connect one set and see how it runs, then connect other set - if speed changes then that is more confirmation it is probably two speed motor.

 

[LarryFine]

Connecting Motors for a Change Of Voltage

AC Motors, electrical basics

www.industrial-electronics.com

 

[StengthThroughUnity]

Maybe the others were no good. How long before they crapped out? Did they run at all?

-Hal

I started the motors long enough to check rotation of the fans. Then maybe ran everything to full speed and checked again without any obvious issues. It wasn't until later production notified me the fans weren't working again and I found some blown fuses and brown liquid oozed from the motors.

This time I'll determine the coils first. Wire them for low voltage, and then check amp draw on each leg. Does anyone recommend anything else to insure no more damaged motors?

 

[StarCat]

What kind of Freezer and who made it?
Condenser or Evaporator fan motors and where were the replacements supplied from? They did not come with wiring diagrams?
What does the OEM say about replcement motors for this application? Are you using NON-SPEC motors? If so this is genrally a mistake on refrigeration gear.
Once you set rotation you must have a current clamp right on and read amps noting starting inrush and stable amps at speed before you walk away from any replacement. You have to know its in range for nameplate or the job is not finished.

 

[kwired]

I have several 3 phase 6 wire motors without nameplates from an industrial freezer. The supply voltage is 208. So I wired a couple motors in Delta for low voltage L1-T1-T6, L2-T2-T4, and L3-T3-T5 only to find the motors overheat and fail. The same thing happened when I tried wiring them in Wye L1-T1, L2-T2, L3-T3, and T4-T5-T6 over heat and fail. The only motor that works and was already on the freezer is wired L1-T4, L2-T5, L3-T6, and T1-T2-T3. This appears to be Wye wired backwards! How is this motor working when my other motors wired in Wye failed?

Are they by chance rated for "air over" use and you are using them for something other than what they are designed for? Not enough air flow to keep them cooled?

You said from an industrial freezer, but didn't make it clear if that is where they originated, if that is your application, or otherwise.

 

[Ainsley Whyte]

I have several 3 phase 6 wire motors without nameplates from an industrial freezer. The supply voltage is 208. So I wired a couple motors in Delta for low voltage L1-T1-T6, L2-T2-T4, and L3-T3-T5 only to find the motors overheat and fail. The same thing happened when I tried wiring them in Wye L1-T1, L2-T2, L3-T3, and T4-T5-T6 over heat and fail. The only motor that works and was already on the freezer is wired L1-T4, L2-T5, L3-T6, and T1-T2-T3. This appears to be Wye wired backwards! How is this motor working when my other motors wired in Wye failed?

do you have the name plate of the motor can share ?

 

[StengthThroughUnity]

do you have the name plate of the motor can share ?

No these old motors appear to have been reconditioned and the nameplates have been removed. I have no information besides numbered wires coming out of the peckerhead.

Are they by chance rated for "air over" use and you are using them for something other than what they are designed for? Not enough air flow to keep them cooled?

You said from an industrial freezer, but didn't make it clear if that is where they originated, if that is your application, or otherwise.

Sorry for any confusion. Yes these motors originated from this big old CES freezer, and are going back into it. However, they appear to have been refurbished. The mass amount of liquid nitrogen they blow around should help keep them cool but I guess these motors melted their insulation before the freezer got down to temperature.

What kind of Freezer and who made it?
Condenser or Evaporator fan motors and where were the replacements supplied from? They did not come with wiring diagrams?
What does the OEM say about replcement motors for this application? Are you using NON-SPEC motors? If so this is genrally a mistake on refrigeration gear.
Once you set rotation you must have a current clamp right on and read amps noting starting inrush and stable amps at speed before you walk away from any replacement. You have to know its in range for nameplate or the job is not finished.

This is a CES industrial freezer. It blows in liquid nitrogen at various points and these motors and fans are responsible to circulate the air. There are no condensers or evaporators. The motors I received appear to be the same OEM motors taken out but they have been rebuilt. I have no clue what nameplate specs are without any nameplates. So should I wire them in the manner that draws the least amount of current?

 

[ptonsparky]

No these old motors appear to have been reconditioned and the nameplates have been removed. I have no information besides numbered wires coming out of the peckerhead.


Sorry for any confusion. Yes these motors originated from this big old CES freezer, and are going back into it. However, they appear to have been refurbished. The mass amount of liquid nitrogen they blow around should help keep them cool but I guess these motors melted their insulation before the freezer got down to temperature.

This is a CES industrial freezer. It blows in liquid nitrogen at various points and these motors and fans are responsible to circulate the air. There are no condensers or evaporators. The motors I received appear to be the same OEM motors taken out but they have been rebuilt. I have no clue what nameplate specs are without any nameplates. So should I wire them in the manner that draws the least amount of current?

That would be my SEWAG. How many more do you have to wire up?

 

[Jraef]

So IF they were originally used as 2 speed motors, you would have had 2 (or 3) contactors in the starter panel and 6 wires going to the motors. Since you said they were removed and refurbished, does that mean that you still have the original controllers for them?

If there were 6 wires going to the motor, you still will need to know if they are 2S2W or 2S1W. If the contactors are still there, a 2S2W will only have 2 contactors, a 2S1W will have 3.

then if you have 3 contactors, you will STILL have two possibilities: 2S1W Variable Torque, or 2S1W Constant HP. Being fans, it is LIKELY Variable Torque.

Here would be the connection patters for 2S1W motors.

IF there is only ONE starter and you only have 3 wires going to the motor, then it is NOT a 2 speed motor. But if it is a single speed motor, there are still several possibilities: Wye Wound, Delta Wound, or Dual Voltage.

Here are the possible diagrams for those.