O/T 3rd Contacter with shorting bar

[gbradley]

We recently received a Leroi air compressor with a 3rd contactor with all three leads shorted.
I noticed on the old compressor it was wired up the same, but used a bar to short all three leads.
I think that this is a Wye/Delta starter arrangement.
Is this a pretty common starting circuit for compressor motors?

 

[Aabeck]

yes this is the standard Wye/Delta starter arrangement commonly used on larger motors.

 

[Brijm]

You may also see this called a start/run contactor.