3 phase single voltage motor

[Postle8]

I have a 3 phase 480 volt 60 hz thermal oil heating unit. The replacement motor is a 3 phase single voltage 6 wire motor. Do I connect it Wye or Delta. Or for that matter, how do you determine if a 6 wire motor is single voltage motor and what voltage to use from the name plate. It is not a Wye start, delta run. It has several nameplate ratings but for 60hz the voltage shows 277/480v. German VEM motor.
I've been involved in small industrial wiring for over 25 years. This is some what new to me and I'm having a hard time finding information on 6 wire single voltage motor applications.

 

[ActionDave]

Welcome to the forum.

How are the leads labelled?

Typically you would wire up a six lead IEC motor in star/wye for 480V

 

[Tony S]

Drop VEM an e-mail

http://www.vem.fi/en/contact

 

[don_resqcapt19]

I have a 3 phase 480 volt 60 hz thermal oil heating unit. The replacement motor is a 3 phase single voltage 6 wire motor. Do I connect it Wye or Delta. Or for that matter, how do you determine if a 6 wire motor is single voltage motor and what voltage to use from the name plate. It is not a Wye start, delta run. It has several nameplate ratings but for 60hz the voltage shows 277/480v. German VEM motor.
I've been involved in small industrial wiring for over 25 years. This is some what new to me and I'm having a hard time finding information on 6 wire single voltage motor applications.

You need to verify, but it is not unusual for European motors to use two voltages that differ by a factor of the square root of 3. In those cases you connect in a wye for the higher voltage and in a delta for the lower voltage.

 

[Postle8]

Thank you all for the replies.

Thank you all for the replies.

I haven't heard back from VEM. Thermalcare Mayer responded to connect the motor Wye. In this instance, their unit would be a 3 wire Wye without a center tap neutral connection. Being this motor is attached to a small centrifugal pump, I can see that there is no need for a higher torque load. But Wye not connect delta? (excuse the pun).

 

[kwired]

I haven't heard back from VEM. Thermalcare Mayer responded to connect the motor Wye. In this instance, their unit would be a 3 wire Wye without a center tap neutral connection. Being this motor is attached to a small centrifugal pump, I can see that there is no need for a higher torque load. But Wye not connect delta? (excuse the pun).

Wye connected motors (at least those under 600 volts) never connect anything to the neutral of the wye point.

Wye, connect in wye and not delta when you have the ability to configure either way?


draw out the motor coils - in both configurations and assume a 480 volt supply.

If you connect them in delta and apply 480 volts to each corner - you apply 480 volts across each coil - those coils need to be rated to have 480 volts applied to them or they will let smoke out - especially if rating is well under 480.

Now look at those same coils connected in a wye configuration with 480 volts applied to the outer ends of the wye. The voltage from each end to the neutral point will be 277 volts (across the same coil you connected to 480 volts in wye configuration).

It is common for European motors to be connected delta when connected to a 240 volt system but connected in wye on a 415 volt system because of how that works out.

North American wiring systems don't typically have a 1.73 factor difference between nominal system voltages. We typically have nine or twelve lead motors and we either parallel or series connect portions of the windings when we have a dual voltage motor.

A six lead North American motor that is not two speed motor is very likely intended to be used as either part winding or wye -delta starting. The wye - delta is the same thing as mentioned before, when in the run mode it is a delta connected motor - if you apply 480 volts each coils sees 480 volts, but if you connect them in a wye and apply 480 volts each coil only sees 277 across it, which for just a second or so is all they energize it this way for to reduce inrush current, it will not have sufficient torque to continue to accelerate a load if you leave it connected in the wye configuration.

 

[Jraef]

What happens a lot is this:

They make their motors for 380/230V, where you connect in Wye (they call it Star) for 380V and Delta for 230V. Motors provide torque based on a ratio of Volts and Hertz being constant, +-10% in most cases. So a 380V 50Hz motor is designed around a ratio of 380/50 = 7.6V/Hz. If you connect that same exact motor to 460V 60Hz, the ratio is 460/60 = 7.67 V/Hz, almost identical. So you can use that motor in the EU and North America very easily, only the speed will change (because of the 60hz).

But that same motor, if connected in Delta, is looking for 230/50 = 4.6 V/Hz, and if you connect it here to 230V 60Hz, it's only seeing 3.83V/Hz, 17% less, outside of that +-10% tolerance. So when sold here, it is sold as a single voltage motor because if connected to 230V, it will not have rated torque, the slip will be higher, it will pull more current and do less work and it will burn up under full load. In theory they COULD de-rate it and it would likely work, but the de-rate would need to be about 30% (70% max load) and a lot of people would not understand that.