Shorting relay?

[Electron_Sam78]

Troubleshooting a control panel and came across this contactor (KM3). It looks like when activated it shorts all phases? What is the deal?

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[Electron_Sam78]

It looks like the pic came out fuzzy but it's the one connected to M1 on the far right.

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[winnie]

Yes, the job of that contactor is to short all three phases.

The reason is that this is a wye start/delta run motor.

With KM2 open and KM3 closed the motor is connected wye.

With KM2 closed and KM3 open, the motor is connected delta.

-Jon

 

[Electron_Sam78]

Ok. I don't have a lot of motor experience so I just like to figure out how the systems I work on are supposed to operate. I tested operation and KM3 and KM1 come on at the same time and then KM3 kicks off at the same time as KM2 comes on. Looks like it fits your explanation. Thanks!

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