Motor Star & Delta Connection

In one of the common "terminal board with jumpers" types:

Star:

O-O-O

OOO
| | |
L L L

Delta:

OOO
| | |
OOO
| | |
L L L

(Sorry about the weak formatting system here. O = motor terminal: L = line: - or | = jumper strip.)

Sorry I forgot to mention that there is no terminal wiring diagram on the motor.

What I gave was just one example I've seen. There may wire leads rather than a terminal block. If so, look for markings on the wires such as U1, U2, V1, V2, W1, and W2. Sometimes such markings are hard to see, but they may be there.

No any other data available dear..........Isn't there any methods for identifying the starting & ending terminals?

The motor nameplate should give important data like connection(star or delta),voltage (single or dual),speed etc. If nameplate is not available ,consult a motor rewinding shop

to check the winding and give you guidance.

An ohmmeter can get you partly there; at least it will tell which wire or terminal pairs are connected to the same winding. But it won't tell you the direction or polarity. There was a CR4 thread about this, but I don't remember the title. This isn't much help, but maybe a start....

I suppose the voltage is a total guess, too?

That's the one I was thinking of; what was the thread's title?

Hi Tornado,

The thread you are referring to was 'Motor Wdg. Start and End Lead Identification' and the OP was 'cmaguna'. This was about a month or so ago and the replies should have answered virtually anybody's questions regarding this problem but there again, perhaps the old adage about 'history repeating itself' rings true again.

My advice to Hardworker2011 is (as suggested by another poster) to take the motor into a competant winding shop and then spend some time improving his search and reading skills. I am not trying to be insulting, dear, but just practical.

But perhaps this is just another homework question from a student who believes they have found an easy way to have someone else do their work?

This the correct procedures for checking of continuity of coils, polarities, and colis connection in STAR or DELTA formation.

HI HARDWORKER

Do some Hard thinking too.

Do you know how to check continuity

If you do -you can tag 3 different pole coils with 2 ends each.

Rest is simple if you know a little about Y AND .

Best of luck

mm

Thanks everybody........special thanks to Brich for the convincing answer.

Dear Tornado"I had already mentioned in the starting that I have identified the winding ends,obviously thru continuity test.

Dear Keith grewar:If you dont want to help,at least don't discourage others for posting questions which many engineers found difficult to answer.

Mukulmahant:I simply didn't get you.(read my question carefully.Already I had told that windings end were identified).

Thanks to all.

1. Question: How to find out Motor Terminal?

Answer:

i) With a multimeter or continuity tester, you can segregate three sets of windings. Can't you?

ii) Now, assume one set of windings to be, say, winding "U" and also, designate its terminals as assumed "U1 & U2".

iii) Take a 9V Cell; Connect + ve of Battery to the assumed "U1" preferably thro a push-switch and - ve to the assumed "U2".

iv) Connect a zero centred galvanometer, to another set of winding, say winding "V" such that the assumed "V1" is connected to the + ve terminal of the galvanometer and the assumed "V2" to the - ve terminal of the meter.

v) Now, when the switch is pressed, the zero centred galvanometer would deflect in the positive direction, if the assumed "U1, U2, V1 & V2" are correct.

vi) Else, if the deflection is on the negative side in the galvanometer, change your assumptions for either one of the winding (That is may be the assumed U1 can be U2 and the assumed U2 is U1 . Or keep the assumptions for U winding as it is and reverse it for the V winding (that is assumed V1 is V2 and assumed V2 is V1).

vii) Repeat this test for applying voltage to other windings and confirm your terminal assumptions.

What I want to know is two things:

1) How is it that so many motors end up with no winding connection information? Are people so ignorant that they think the nameplate is inconsequential in a motor and they remove it?

2) Why would someone persist on using a motor that has no nameplate data and therefore cannot be easily connected? Do they place ZERO value on the amount of time they spend trying to figure it out? To my mind, small motors are too cheap to fuss with, and larger motors are generally associated with high revenue processes, so down time costs should be considered paramount in selecting the proper equipment. Both scenarios preclude the use of junk motors that have obviously already been abused as evidenced by the lack of proper nameplates and connection details.