A question for the motor Guys....

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AdrianWint

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Midlands, UK
So I have a (new) 1.5kW 3 phase induction motor.

Inspection of the terminal box reveals that all 6 ends (ie. each end of the three windings) have been brought out into the box.

The links have been fitted to configure the windings into STAR.

Normally I would expect the motor plate to give me parameters for this motor when configured both in star & in delta, but the plate only gives me details when configured as a star - even stating 'Wired in Star'.

My question is - why would the manufacturer restrict the use of the this machine to STAR? What bad things might happen if it where configured as delta (and the correct voltage applied for that configuration!)

In particular, this motor is set up for 380V 60Hz in STAR mode. I need a motor which is 220V 60Hz. Normally I would reconfigure this motor into delta & run it on a 220V (line-line) supply.

I'm not arguing with the motor rating plate - the plate says I can't do it, so I won't. I'm simply trying to understand what it is about this motor that makes its use in delta undesirable.

Can any of you Motor guys shed any light on this?
 
Does the rating plate actually say you can't use a delta configuration, or is it just silent about it?

It's doubtful anything bad would happen. It's likely they just didn't mention it because 220-volt supplies don't exist in the country where it was designed, and a motor this small won't need wye-delta starting.
 
drcampbell said:
Does the rating plate actually say you can't use a delta configuration, or is it just silent about it?

It's doubtful anything bad would happen. It's likely they just didn't mention it because 220-volt supplies don't exist in the country where it was designed, and a motor this small won't need wye-delta starting.
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Nope. It doesn't say don't - its merely silent about that configuration. I agree about not needing to do wye/delta starting on a motor this small, thats not what I want to do.

220/380 60Hz is a common supply in parts of Europe. Its a common 'trick' to use a single phase inverter drive to take in 220V single phase & spit out 220V line/line 3 phase. One would then take a 380 Star/220V delta motor, configure it into delta & run this from such an inverter. This is what I need to do.

I've done this many times before, but this is the first time I've come across a rating plate that is silent about the possibility of running in delta even though the terminal box appears to be setup to allow that possibility.
 
drcampbell said:
It's likely they just didn't mention it because 220-volt supplies don't exist in the country where it was designed, and a motor this small won't need wye-delta starting.
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I agree; we never shipped to Europe where the supply wasn't "400/3/50" (call it 380, 400, or 415 or whatever). I can think of no reason it wouldn't be perfectly happy wired delta vs star (I call it wye). I'd ask the motor manufacturer.

But, OTOH, I've never seen a STANDARD motor designed for "400VAC" and 60 Hz either, so who knows. I'd ask the authoritative source, the motor manufacturer.
 
380V 60Hz is not at all common anywhere. It would be 380V 50Hz. So that means if you configure it in Delta, it would be 220V 50Hz for a VHz ratio of 4.4:1. If you try to use it here at 240V 60Hz it would be 4:1, which is 10% low so it would have significantly less torque and IEC motors have very little margin of error in their design. So peak torque, which the motor uses to re-accelerate after a step change in load, wold be reduced to 82% of what the motor should be able to produce. Under the right circumstances that might be acceptable, but the motor mfr cannot assume that a user will understand the ramifications.
 
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The 400V system is the harmonized voltage level in EU countries (380, 400, 415V). If rated at 400V- wye, the phase voltage would be 230V. As I see it, that motor is good for 230V/60Hz, 3-phase (delta).
 
retirede said:
Years ago, we supplied 380/60 equipment to Brazil. I don’t know if they still have that there or not?
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Yes, Brazil is still one of the few odd ones as far as voltage and frequency goes. One of the reasons Weg exists is because Westinghouse decided to build an entire motor manufacturing plant in Brazil because of the oddball V/F situation since the motors basically couldn’t be used anywhere else. The name Weg stems from their castings having WEG molded into them for Westinghouse Electric Group. When Teco bought the old Westinghouse motor division, they didn’t want that oddball Brazilian unit, so it was bought by local Brazilians and since the castings already said WEG, they made that the name of the company.
 
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