How to determine polarity on three phase motor? 7

[cccelcj]

Is there a procedure for determining how to properly identify the leads on a 6 wire 3 phase motor? The motor leads are unidentifiable. The nameplate only shows T1, T2 and T3 connections. This is a 460v, 150hp motor. Any direction would be greatly appreciated.

 

[waross]

A further note, it is possible that the breaker may not trip on the instanteneous trips with the motor on the star connection even with one winding reversed. You may have to trip it manually.
respectfully

 

[wiretwister]

The simple way to determine the polarity of the windings Ie: start and finish, is the inductive kick method.
1> Tools Needed---One old Simpson Multimeter, a 6 volt lantern battery,some gator clip jumpers and a book of tape on numbers.

2> Proceedure---Identify the three pair of leads with the resistance function of the Simpson. Wrap a piece of tape around each pair just so you don't get lost.
Take the lantern battery and connect the negative post to one lead from one pair.Use a Gator Jumper.
Connect the Simpson to one of the remaing pairs. Select the meter to read dc voltage (50v range)
With another gator jumper attach one end to the positive terminal of the battery.Then just touch the jumper to the other motor lead of the first pair.
Observe the meter when you touch the lead. You will see a deflection (forward or reverse). Remove the the jumper and you should see another deflection in the opposite direction.Do this several times to get the feel.
What we are looking for is a forward deflection when you take the jumper off.
Reverse the meter leads if needed to to achieve this.
Mark the first pair [Batt(+)=T1 Bat(-)=T4]. Second pair [Meter (+)=T2 Meter (-)=T5].
Connect the meter to the third pair and repeat the same proceedure as before leaving the battery on the first pair.
Reverse the meter leads if needed.
Mark the third pair [Meter (+)=T3 Meter(-)= T6].
3> Now that you have identified the the T leads, determine from the name plate if this a dual voltage motor or not.
If it is dual voltage, tie T4, T5, and T6 together for the lower voltage.[wye or star]
Tie T1 to T6, T2 to T4, and T3 to T5 for the higher voltage.[delta]
If the motor is a single voltage, connect T4,T5,and T6 together and insulate. Line on T1-T2-T3.

This method is used to determine the polarity of a current transformer.It worked for me in motor applications as well.
Lots of luck!
I hope you gained some useful info.
wt

 

[itsmoked]

wiretwister;.... Very nice! Well stated.

You should convert your post to a FAQ!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[cccelcj]

Thanks guys. I have indeed gained some useful information. I have printed and filed all your replies for future usage. The issue has been resolved thanks to your timely and accurate responses.

 

[waross]

Hello cccelcj
We do appreciate the feedback. Thanks
respectfully