STAR/DELTA QUESTIONS

What about other 3 wire ends, U2, V2 and W2 also lost the lables???????

what you mean by three cables?

Starter Panel to Motor terminals or Motor Stator winding to Terminal Box?

Ediri

send me wiring diagram for star deltm & deltm star

I am not sure what you are after here please explain a bit better. If you want to know which ends of the windings are which and you know which are U2 V2 W2 just use an ohm meter or preferably a megger to test the windings and find the correct ends. If you dont understand how to do this then I suggest you get an electrician.

Thank you for your reply

im still not 100% with it.

Perhaps if i decribe it in another way

if on a star/delta motor all the leads are connected to the motor and are in the right place. Leads u1,v1and w1 are connected to the main contacter but the other ends of the three leads w2,v2 and u2 which would come out of the overload have been disconnected then say there are no lables by the overload to say which position they should be in. what is the method used to find out which one goes where.

Many thanks

Tim

You should have 6 cables, three pairs. You can find the pairs with an Ohmmeter. Then, you can connect them as usual.

------- if in doubt:

At low voltage:

It must rotate. Then slowly you will gain confidence.

Then you try Star/Delta -- again at lower volts -3 ph.

What?

In another life, I was a motor-winder. In the situation your describing, we would connect the motor to a 480V test bench that had the terminals label Phase A, B & C. While facing the drive end of the motor, if it spins counter-clockwise, we would label the lead connected to terminal marked phase A, U1. Phases B & C were marked V1 & W1 respectively. If the motor spins clockwise switch two of the labels. If you have incoming in the plant marked brown, yellow and orange you can use that to. I have assumed you have a direction sensitive application.

I hope I haven't missed the mark for the situation you presented. I hope no one fillets me if I have.

Cheers,

Dan

Thank you for your reply

im still not 100% with it.

Perhaps if i decribe it in another way

if on a star/delta motor all the leads are connected to the motor and are in the right place. Leads u1,v1and w1 are connected to the main contacter but the other ends of the three leads w2,v2 and u2 which would come out of the overload have been disconnected then say there are no lables by the overload to say which position they should be in. what is the method used to find out which one goes where.

Many thanks

Tim

Look.

• The U1 is connected via a motor winding to the U2 wire.
• The V1 is connected via a motor winding to the V2 wire
• The W1 is connected via a motor winding to the W2 wire.

So you can buzz them out with a meter to determine which 1 is connected to which 2, and prove the motor. OK? Before you go any further, put a label on the wires so you konw which one is which. Don't worry about the direction of rotation at this time.

OK. Now for the starter. There should be a wiring diagram for it and if there isn't there damn well should be because you need to be able to determine the following:

• In star, U1, V1 and W1 are each connected to a phase via the main contactor, and there should be another contactor, the star contactor, energised at the same time to short out U2, V2 and W2.
• In delta, the shorting contactor de-energises before a third, delta, contactor energises and connects U2, V2 and W2 to the incoming phases, but 120deg out-of-phase forwards relative to their respective 1s. But it needs to be right, otherwise the motor will go from star forwards to delta backwards and the fuses will go if there's a significant load on the motor, and probably if there isn't.
• That arrangement should be driven by a couple of timers in the control circuit, so that star happens while the motor spins up, then there's a short break, then delta happens. The break is there to give the shorting contactor time to drop away.
• Contactor 2 and contactor 3 should be mechanically interlocked so that it is impossible for them both to be closed at once. If the interlock is missing and they do then will happen, and you'll lose the supply fuses and probably your eyebrows, every time.
• Once The Us, the Vs and the Ws are connected properly and the motor spins up in both star and delta, check the direction of rotation. If it's wrong, swap over any two of the phases coming into the starter cubicle.
• Then connect the motor to the mechanical contraption it is driving and walk away in your Clever Clogs.

There. Dunnit. There's life in the old git yet.

Thank you very much for that information

Tim

Sorry, my previous post should have read:

While facing the Opposite drive end of the motor, if it spins

instead of what I actually posted which was "While facing the drive end of the motor, if it spins"

Check sections 5.1.4 "NEMA Standards Publication Application Guide For AC Adjustable Speed Drive Systems" it is a free download from

http://www.nema.org/

Good Luck

At last ,a confession,after all these years of rewound motors which never have the windings marked correctly,and ALWAYS go the wrong way.(unless star/delta when they hum ominously in delta before the overload melts)

Your retraction was too late,now we know it was deliberate,not a 50/50 chance.

"Your retraction was too late,now we know it was deliberate,not a 50/50 chance." Thanks for the fillet, you are so cute. It was my first post and I didn't know there was a time limit. I was actually preparing my lunch.

I was also assuming it was a 6 lead motor and the other sides would "ring out" and be labeled accordingly, then terminated based on the contactor. If it had 9 leads it would have led to a different suggestion.

If you were getting motors rewound and had this problem "wrong way... [Or] ...hum ominously" then either your incoming wasn't phased properly or you picked bad motor shops to do business with. Any motor shop, worth its salt, will have the leads labeled to the NEMA standard connection diagram before it ships.

Also see:

http://globalspec.ip09.com/rd/9z1zitld5a93s7qelrn1f9s2aftnica3ghhtlma8t00

Hi all, we are unnecessary complicating the matter. Looking at the terminal box of motor from left to right U1, V1 & W1 as convention. Verify

please send star delta connection & drawing and how to check winding fault?

I think you have to go for professional consultation.

hi am looking for some

drawings for connecting eletric motors as i need them for study as i dont no were to get them mainly 3 phase like star delta