STAR DELTA Connection of a Motor

The motor rewinder has told you how to connect it.

If he has rewound it then what makes you think that anyone here would know more than him about how it should be properly connected. It may no longer be wound the same as the original name plate suggests.

I am guessing that since it has burnt out twice already that you are not taking his advice, so you would be unwise to take that of anyone who does not know the motor as intimately as the person who wound it.

But The manufacturer is giving the information that motor is to be connected in Y for 460V power.

If the motor rewinder you are referencing to performed a rewind on the motor in question and is telling you to connect the motor in DELTA I would ask why they altered the winding from OEM specifications.

If permission was not given to the rewinder allowing alteration of the motor winding and you need the motor to be dual voltage as per OEM design, I would return the motor to the rewinder and demand the motor be returned to OEM specifications or find a different motor rewinding shop that is willing to do so.

One alternative would be to get the motor winding detail report and a statement of warranty from the rewinder before applying voltage to the motor so that the rewinder is responsible for any/all motor damage. Make sure to get a hardcopy motor connection diagram from the rewinder illustrating details on their directions for making motor connections as this may be a simple misunderstanding and/or confusion.

I guess if you DIDN"T listen the first two times then the third times the CHARM!

Like this one!

You may be reading the OEM name plate wrong. I have never seen a 230V delta - 460V Wye wound motor before. Not saying such a beast could not exist, just that I have never seen one.

Good point. Recheck the name plate. I recently-just last week- changed out a 3 phase motor and having delta in my shop installed the jumpers accordingly based on the wiring configuration in the connection box. Gave me problems of overheating and tripped overload. A closer look at the name plate and delta was the symbol they used for 460 volt 3ph and the Y was for 600 3ph not for the power supply type. Reconfigured the jumpers and voila, no more problems.

Yes. Crompton Parkinson can and they can do it over the telephone too.

I agree with North of 60 #5. I don't understand 460V/Star // 230V Star. If it's 460V star it would be 460/√3 = 265V delta, or if 460V delta, 460*√3 = 796V star.

If the motor has been rewound as the original, from the nameplate it's most likely 460V/Star is correct, but not certain.

Has it been rewound because it failed in some way? Is it a new installation or has it run OK in the past?

I think you should get the rewinder on site to witness and agree the connection, and take responsibility. And bring his multimeter to check he's happy with the supply voltage!

Maybe there's something wrong with the way the 12 leads are connected to the 6 studs in the terminal box. If so it's down to the rewinder to put it right.

The numbers 460 star and 230 delta don't match. They should be in ratio of sqrt 3 with each other.

Give us the comlplete nameplate data of the motor.

there are 12 leads. that means, each phase has two windings. these can be connected in series or parallel. in parallel, the machine will work on 230v star. in series, it will work on 460V star.

Normally 6 wires are enough for star-delta. 12wires are needed only for dual voltage(220 and 380V)motors like british motors made by GEC. 9 wires are used in US motors. Give us the nameplate data.

it is already given by original questioner.

460 star should work on 230 delta. First run in 460 star check current as per nameplate,if ok connect in delta in 230. If it doesn't work winder has changed something claim damages from him. Name plate should give current rating in 460 as well as 230 star and delta,that's why I asked for it.

The Brook Crompton handbook shows a 12 wire "Dahlander connected" pole change dual speed motor. Get the connections mixed up and you're in big trouble.

http://apps.motorboss.com/connections/390880.pdf

Here is a link to clear up the apparent confusion on 12 lead dual voltage Y motor connections.

Please note there are numerous motor connection illustrations available at the motorboss.com website that pretty much cover all standard motor winding types and connections.

From the limited information you provided it appears to me that you have a Y-Y wound motor which the 390880 connection diagram and information should match.

Note:

When the Y-Y motor is connected for high voltage the windings are connected in a Y+Y series configuration which allows maximum winding impedance.

When connected for lower voltage operation the windings are connected in a parallel Y/Y which allows half of motor winding maximum impedance.

It is possible and very easy to connect the motor wrongly.

Motor horsepower/power (P) is a function of current (I) squared multiplied by impedance/resistance (R) or (Z).

The Volts-per-Hertz ratio factor determines developed motor torque and horsepower especially at lower voltage applications.

In the USA at 60HZ the volts-per-hertz ratio for a 460V motor is: 7.6666

For the same motor operated at 50HZ and 460V the ratio is: 9.2

As you can see it is possible to have a 17% loss of power when operating a 50HZ motor at 60HZ.

It may well be that the motor application power requirements are above 83% due to energy efficiency design concerns.

If so, the 50HZ motor is suffering HP loss and high current loading because it cannot produce enough HP to satisfy the application requirements. (This would account for the high incidence of motor failure you are experiencing.)

I suggest you determine the process application motor requirements then purchase a 60HZ, 460V high quality motor that exceeds those requirements by at least 10% to account for occasional operational and mechanical overloading instead of rewinding the existing motor.

Good luck and stay safe.

Your original post has a discrepancy, one place you say 460 star/230 star and another you say 460 star/230 delta. I'm surprised you didn't just tell the rewinder to make the winding interconnections and you just make the final connections. Have you checked the current draw unloaded and under load? Are the overloads sized properly for the motor? And lastly, maybe the motor is over-loaded. If the motor was sized for the pump at 50 Hz and it's running at 60 that would cause a sizable increase in power demand. And if this is a centrifugal pump and it is running at significantly higher flow than design, the power requirement could be also increased.