Running a 3-Terminal, 74-KW Motor

Need all of the name plate information--3 Phase, number of poles, Horse power, voltage, Hertz........

Dear Frd,

As you said u hv 75KW Motor with 3 terminals, & u dont hv vtg ratings of it.....

as per logic, 3 phase LV motors are always connected in Delta with six terminals. tht means your motor is not 3 phase.

Motor may be single phase 230 V AC. so connect phase, neutral, earth accordingly.

Even u dont knw which terminal is Phase & neutral & earth....then check the megger on phases...or check the resistance across terminal..... Earth & phase shud be open....

Hope u get the right answer....

Vishal, Shj, UAE

Motor may be single phase 230 V AC. so connect phase, neutral, earth accordingly.

Errr .... single phase ? 75KW ? 230V ... that is errrr ... 75000 / 230 = 326 Amps .... ??????

Where did you last see a 100HP single phase motor? The rest is of course, total nonsense.

Wangito.

zub kci; you could use a electronic soft start control, or a reactor, or a autotransformer starter perry

Hi

Some more data could be of great help...

But suppose that this is all you have...

Any three Phase motor could be connected either in Δ or Υ connections. All conventional three phase motors have 3 windings. and they are marked T1-T4, T3-T6, and T2-T5 .And usually have their connections built on a terminal strip on the motor frame, so you can connect it they way you need. What I think is happening in your case is that the motor is wired in such a way that you can connect it in "star" or Y. That means that the ends T4-T5-T6 are internally shorted fot Y. If T4 is shorted to T3 , T1 to T5 and T2 to T6, internally than you could make a Δ connection. Your connection will be than (by US standards) L1 to T1, L2 to T2 and L3 to T3. If you have to make a Δ or Y connection, you will have to dig into the motor, untie the shorts, and bring the ends out, install an additional terminal strip and wire it the way you want externally. To reverse the rotation, all you need to do is reverse one of the phases. A motor of that magnitude and medium load will need a soft start of some kind, unless your grid can handle it...

Hope this helps.

Wangito.

I agree with wangito that the links have been made internally which would be when it was rewound as I have never seen any manufacturer do this with a new 75kW motor. also the original terminal box must have been damaged or there would have been no reson to make the link internally. Before doing any connection make sure the name plate voltage matches yours in the Y connection or else you could be in all sorts of trouble. If there is as I suspect no name plate then contact the people you bought it from and get them to send you conformation that the motor will run correctley as wired and get a guarantee. If you have enough power available I would use a DOL starter. Because if the motor turns out to be a dud then you havent also destroyed an expensive electronic soft starter.