6 Lead motor connection

[PhaseShift]

We have a 4.16kV 600hp 6-lead motor. We are debating weather to hook it up in the wye or delta configuration.

Since we have a 4.16kV system and the nameplate on the motor only says 4000V then I am saying we connect the motor in a delta config. Only if the motor was a 2300V motor would we connect in a wye config on our 4.16kV system.

Am I correct in thinknig this?

 

[Cold Fusion]

We have a 4.16kV 600hp 6-lead motor. We are debating weather to hook it up in the wye or delta configuration.

Since we have a 4.16kV system and the nameplate on the motor only says 4000V then I am saying we connect the motor in a delta config. Only if the motor was a 2300V motor would we connect in a wye config on our 4.16kV system.

Am I correct in thinknig this?

I take it that it is an old motor, no connection data on the nameplate, nor any literature showing the intended connection, it's been sitting on the shelf long enough that no one remembers how it was hooked up, no similar motor is service, and you can't call the mfg to ask?

Having only a single voltage on the nameplate and all 6 leads brought out sure makes it look like a delta connection. If it was single voltage and wye, I'd only expect three leads - the wye point would be inside. If it was dual voltage then I would expect the nameplate to say so.

However, 600hp is big enough that I'd work at getting another method to verify.

cf

 

[Besoeker]

We have a 4.16kV 600hp 6-lead motor. We are debating weather

Why? Do you think it will rain?
Too amusing to let it pass.

to hook it up in the wye or delta configuration.

Since we have a 4.16kV system and the nameplate on the motor only says 4000V then I am saying we connect the motor in a delta config. Only if the motor was a 2300V motor would we connect in a wye config on our 4.16kV system.
Am I correct in thinknig this?

Tough call for you. A 600 hp motor wouldn't normally be considered a consumable item so cooking it isn't an option.
I also have a concern about the 4000V on the nameplate. The 4160V at nominal voltage would be already 4% above nameplate rating. Add supply voltage tolerances then maybe the situation isn't so good.

Can you provide all the information on the nameplate? A picture of it maybe?

 

[Cold Fusion]

---I also have a concern about the 4000V on the nameplate. The 4160V at nominal voltage would be already 4% above nameplate rating. Add supply voltage tolerances then maybe the situation isn't so good.---

In the US, 4000V is the norm for 4160V systems. It's about the same as 460V motors on 480V systems.

cf

 

[PhaseShift]

It turns out that we recieved a connection diagram from the manufacturer that states the motor should be wired in a wye connection. This motor was confusing to figure out only becuase the datasheet that came with the motor had a "High Voltage" and "Low Voltage" connection listed and only had nameplate information of 4000V. Most 6 lead motor that I have seen are connected in delta unless used as part of a wye-delta start, or a dual voltage european conversion. Is this usually not abundantly clear with larger motors?

I guess this motor was designed to have 2300V across its windings as opposed to 4.16kV as you would with a Delta connection. When we tried to operate this motor wired up in delta we blew the contactor fuses (more voltage at start lead to greater starting current) and we started questioning the wiring. Had we not blown fuses I guess we could have eventually damaged the motor leaving it connected in delta.

I guess the lesson here is to ask the manufacturer when it is not clear.

 

[Jraef]

We have a 4.16kV 600hp 6-lead motor. We are debating weather to hook it up in the wye or delta configuration.

Since we have a 4.16kV system and the nameplate on the motor only says 4000V then I am saying we connect the motor in a delta config. Only if the motor was a 2300V motor would we connect in a wye config on our 4.16kV system.

Am I correct in thinknig this?

As a grossly general rule, large 6 lead single voltage motors are usually used to be ready for Wye-Delta starting in case you want to do it that way. If you are starting Across-the-Line, or with an Autotransformer, Reactor or Solid State Soft Starter, or you plan on using a VFD, you would use the Delta connections.

There is a standard configuration for what is called "Part Winding" start that uses 6 leads as well. You really need to try to discover which way it is.

That said, these would be the NEMA standards, but NEMA standards don't necessarily apply to motors over 250HP. MOST manufacturers will still use that convention just for the sake of consistency, but some do not. That's why it was suggested earlier that you use real motor nameplate or manufacturer's data.

PS: Oops, this response was sitting on my browser for too long... again.

 

[PhaseShift]

As a grossly general rule, large 6 lead single voltage motors are usually used to be ready for Wye-Delta starting in case you want to do it that way. If you are starting Across-the-Line, or with an Autotransformer, Reactor or Solid State Soft Starter, or you plan on using a VFD, you would use the Delta connections.

There is a standard configuration for what is called "Part Winding" start that uses 6 leads as well. You really need to try to discover which way it is.

That said, these would be the NEMA standards, but NEMA standards don't necessarily apply to motors over 250HP. MOST manufacturers will still use that convention just for the sake of consistency, but some do not. That's why it was suggested earlier that you use real motor nameplate or manufacturer's data.

PS: Oops, this response was sitting on my browser for too long... again.

This motor is a GE motor. Manufacturer has said to wire it in a wye configuration. Should I take his word and wire it that way or should I challenge the manufacturer and ask why it is connected in wye?

 

[hillbilly]

I take it that it is an old motor, no connection data on the nameplate, nor any literature showing the intended connection, it's been sitting on the shelf long enough that no one remembers how it was hooked up, no similar motor is service, and you can't call the mfg to ask?

I like that.

steve

 

[Besoeker]

In the US, 4000V is the norm for 4160V systems. It's about the same as 460V motors on 480V systems.

cf

Thank you for the information.
Is there a reason for making the namplate voltage different to the nominal supply voltage?

 

[Jraef]

This motor is a GE motor. Manufacturer has said to wire it in a wye configuration. Should I take his word and wire it that way or should I challenge the manufacturer and ask why it is connected in wye?

They SHOULD know best, I would trust them. There is a valid 6 lead connection called "external Wye" and as I said, motor mfrs don't always follow NEMA conventions on large motors anyway, so their information would be most likely the most accurate.

 

[LarryFine]

Is there a reason for making the namplate voltage different to the nominal supply voltage?

It's a combination of early, non-standard standards, and expected service and supply voltage drops.

I've seen equipment rated 110v, 112v, 115v, 117v, 118v, and 120v. Not devices, utilization equipment.

 

[wirenut1980]

Thank you for the information.
Is there a reason for making the namplate voltage different to the nominal supply voltage?

Utilization voltage versus nominal supply voltage. It allows for voltage drop from the service point to the equipment.

 

[Besoeker]

It's a combination of early, non-standard standards, and expected service and supply voltage drops.

I've seen equipment rated 110v, 112v, 115v, 117v, 118v, and 120v. Not devices, utilization equipment.

Then you have 208, 240, 277, and 480V, high legs... and stuff. It just seems overly complex.

All we have here in UK for LV is 400 3-phase and, derived from that, 230V single phase. Domestic kit from lighting to cookers and hobs is all 230V.
Simple is good.

 

[Besoeker]

Utilization voltage versus nominal supply voltage. It allows for voltage drop from the service point to the equipment.

Allows for......but defines what is expected?

 

[PhaseShift]

We changed the motor connection to a wye connection per the manufacturers recomendations, and it appears to be working fine and pulling the no-load current close to what is listed on motor datasheet.

Is it safe to sumarize that "most" motors below 250hp will be connected in delta for a normal across the line start with a 6-lead motor, however motors above 250hp may not follow any standards and it is best to consult the manufacturer if not clearly marked somewhere?

 

[wirenut1980]

Allows for......but defines what is expected?

ANSI C84.1 Defines what is expected at the service point and also what is expected at the utilization point. There are requirements for utilities to provide a range of voltage at the service point. These requirements vary, but many follow ANSI C84.1. What is expected at the utilization point can vary based on design decisions, but I suspect most will be similar % voltage drop based on NEC conductor ampacity sizing.

Clear as mud?:grin:

 

[Besoeker]

ANSI C84.1 Defines what is expected at the service point and also what is expected at the utilization point. There are requirements for utilities to provide a range of voltage at the service point. These requirements vary, but many follow ANSI C84.1. What is expected at the utilization point can vary based on design decisions, but I suspect most will be similar % voltage drop based on NEC conductor ampacity sizing.

Clear as mud?:grin:

Of course....