3phase motor wiring codes?

Question

What do W1-2-3 and U1-2-3 refer to on a 3 phase motor winding diagram, and how do you know whether it is connected in star or delta.? Any replies most welcome.

Answer 1

the motor winding diagram shows you the connections of the windings to the terminal block, each winding will have 2 ends U and W (so U1 and W1 are the two connections for winding one).

the motor is designed to be usable in either star or delta mode, choosing which mode to connect it in is left to the specification team.

if you wish to connect the motor permanently in star mode then bridge between the contacts W1 to W2 to W3 and connect your phases L1 to U1, L2 to U2, L3 to U3....

to connect permanently in Delta mode bridge the opposite way, across the termination block, (eg W1 to U2, W2 to U3. W3 to U1) and connect your phase as before.

if the motor spins in the wrong direction then switch any two phases (eg connect L1 to U2, L2 to U1, L3 to U3)

to connect via star delta changeover contactors you will need to run 6 cables to the motor and figure out your connections for the contactors appropriately.

if connecting to an inverter drive the connect in the delta fashion with the inverter supplying the L1, L2, L3

Answer 2

It's best that you read the user's manual.

For an analogy information with no assumptions of liability, it is likely that your motor is a 3 phase with 9 windings, 3 per phase. They allow you to alter between star and delta power, as well as configure the motor to run at different rpm's.

The first letter can be one of U, V, or W: each designates one of the 3 phases.

The second number can be 1, 2 or 3, and designates that the wire is the first, second, or third winding leg of the phase U,V or W.

Because each winding has two ends, to complete a designation some wiring diagrams print the phase letter followed by two numbers, instead of just one: One number designates the beginning of the winding if equal 1 and the end if 2; and the next number denotes the winding leg 1, 2 or 3 of the U, V, or W phase. For example, U12 is the lead to the beginning of winding leg U2, and W21 is the lead ending winding leg W1.

Answer 3

if you want to know how a 3 phase electric motor works look at the nikola tesla patents

Answer 4

You may want to skim through the following web pages and retain the information that you need:


http://en.wikipedia.org/wiki/Electric_motor
http://www.reliance.com/mtr/mtrthrmn.htm
http://www.patchn.com/tutr-mot.htm
http://www.state-electric.com/id11.html