Changing Star Delta Motor Direction

With a 3 phase motor, connected in Star or Delta, you can change the direction of rotation with reversing 2 wires. (2 out of 3, no matter which ones) It can be done at the connector side or on your contactor, that switches the motor on. Do not play with star/delta configurations, unless the motor is built for it and works with your supply voltage.

However, what is shown in your diagram, does not reverse the motor. Both details do the same.

Alright so you can change at the main contactor side . Just to make my self sure ,is the pic that i posted right for changing motor terminals at motor side.?

If you look at the diagrams one by one, they reverse compared with non crossed lines. The block looks like the connector block in the connection box of the motor. These blocks have most of the time 3 copper jumpers in it that you connect parallel in case of delta - when you have to reverse the motor it is easier to do it with the feed wires, instead of doing it with the coil (internal) wires. However, the effect is the same.

Your diagram wont change motor direction, because you undo your change on the opposite terminal. For a star delta direction change it is best to change the 2 wires at load side of your isolator. That way the swap will be correct all the way through.

Simply put and to avoid mistakes:

If your Star/Delta connection is working correctly (because if you mess up the delta contactor wiring you might have the motor reversing sharply when going from star to delta AND THAT CAN BE DESASTROUS FOR YOUR MOTOR OR THE DRIVEN MECHANISM), then all you need is exchange two phases ONLY at the power input lines, at the main contactor (M) without changing the interconnecting wires to the Delta contactor.

As a precaution, you should try your changes with the motor mechanically unloaded and briefly close the (M) & (Star) to check direction, then the (M) and (DELTA) after allowing the motor to stop before doing it. Only briefly. The two rotations should be in the same direction. Don't forget: Motor unloaded, disconnected from the mechanical load.

Thanks for the inputs everyone. Here is the link i found which discusses star delta in detiail .

If you want to change connections only at the motor terminal, then: exchange U1 with V1 and W2 with U2

I have shown the motor coils and the normal terminal numbering that allows Delta connection by straight bars (3), and Star connection by crossing W2-U2-V2.

This is equivalent to exchanging L1 & L2 to reverse the rotation.

You could xchange L1 & L2 at the [M] contactor input Only = Same.

A little imagination and redrawing will be enough to confirm.