6 Lead Wye Delta Motor

[AckAttack]

I have a 6 lead wye delta motor. We currently use three contactors to start and run this motor. I am looking at changeing the way we start this motor to a soft start. 1. What is the best way to wire the motor to accomplish this? 2. If I use a bypass relay with the soft start do I still need overloads on the bypass relay?

 

[Jraef]

1. You would connect the motor in the Delta pattern, so all 6 leads would connect to the soft starter, which means some sort of lug arrangement to allow for this.
2. Yes, you would DEFINITELY need for the OL to be in the Bypass circuit. If you use something like an A-B SMC Flex that has the Bypass built-in, then you don't need to worry about it. But if you are "rolling your own" or if you want the Bypass Contactor to be able to start the motor Across-the-Line should the soft starter fail, then it needs to be a Bypass Starter, not just a contactor. The only issue with that is, the second OL relay in the bypass will not have been seeing the motor starting current, so it will "think" that the motor is cold, when in fact it may be really hot when it takes over. The workaround is to use a separate OL relay in ALL cases located AHEAD of both the soft starter and the bypass, then disable the OL protection inside of the soft starter so you don't have a conflict (although that's not absolutely necessary). I recommend a good Solid state OL relay in any case.