Power Feed for 440Y Motors 1

[bwells]

I have been tasked to replace the controls for a European machine that has motors which list the voltage as 440 Y. As someone who has only dealt with typical North American 460V motors, I am unsure if there is anything I need to be concerned with regarding the incoming power feed to the panel that will house the motor starters. Does it matter whether the transformer feeding the panel is wired in a delta configuration or does it need to be a wye configuration?

 

[rbulsara]

No, it does not matter.

 

[waross]

As you know, dual voltage NEMA motors and transformers use two windings per phase.
The windings are connected in series or parallel for a voltage ratio of 2:1 between rated voltages.
The European practice is to use one winding per phase.
The windings are connected in star or delta for a voltage ratio of 1.73:1 between rated voltages.
Your motor should have its windings connected in star for 440 volts. The corresponding rated voltage if it is re-connected in delta will be 254 volts.

Bill
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"Why not the best?"
Jimmy Carter

 

[jraef]

That's correct. The probable reason why they mention the Y connection is because that is telling the installer that they must connect the motor leads in the Y pattern at the motor, not Delta. The cables going to the motor are no different.

 

[ScottyUK]

Are we answering the wrong question here fellas? As I read it the OP needs to know about the supply characteristics, not whether to connect the motor as star or delta.

To replicate the European supply characteristics, so far as possible in a 60Hz country, the transformer feeding the panel should be a Y with an solidly earthed star point because this is the standard European supply. A floating source (delta) feeding an unearthed star (motor) is inviting problems. If there are any auxiliary supplies within the machine then they may well be connected line-neutral anyway so you will need the star connected source or will need to provide an additional transformer.


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If we learn from our mistakes I'm getting a great education!

 

[rbulsara]

Motor itself does not care where the three phases are coming from.

Source grounding or grounded vs. ungropunded system are altogether different issues. A motor would run just as fine as it would on a grounded source.

 

[rockman7892]

Waross

Wouldn't the motor be 440V on the delta configuration and 256 V in the Y configuration other way around from what you stated? I thought that in a delta configuration the windings would see L-L voltage (440V) and in a star configuration they would see 1.73 times less then L-L voltage?

So if the OP only has 460V available as a system voltage, then what is the best configuration to wire the motor to achieve the required 440V?

 

[waross]

Hi rockman7892;
We have two different cases when considering wye delta connections in regards to motors.
The most common configuration in NEMA land is star/delta starting.
In order to reduce the starting current, a motor may be first connected in star and and then reconnected in delta.
If the motor is to be operated in delta then the windings must be suitable for the full line to line voltage.
For a 440 volt motor, each windings must be suitable for the full 440 volts.
When the windings are connected in star, the 440 volt windings each see only 1.73 of 440 volts or 254 volts.

In IEC land it is common to connect motors and/or transformers in either star or delta.
A motor marked 440Y most likely has 254 volt windings. The motor would be connected in delta for use at 254 volts and connected in star for use at 440 volts. This motor may be star/delta started at 254 volts, but on 440 volts it would normally be started across the line. If reduced current start was desired, some method other than star delta starting must be used at 440 volts.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

Unless it's old equipment you'll only find motors plated for 230/400V or 400/690 coming out of Europe unless they are 'specials'. 440V is right at the extreme upper end of the declared European voltage range.

bwells should have a look at faq237-1224 too, just to be sure the machine will actually work as expected after his mods.




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If we learn from our mistakes I'm getting a great education!