single phase reversing contactor

[cadpoint]

Thanks for all the drawing !

It seems that T5 - T8 is always hot in (mostly) all the diagrams is this reflective of what the motor does with these items.

Say for example, these are the bi-polor winding or windings and stator, respectively?

So we'd really have to understand what all the T's are doing to wire this puppy... even better to draw a napkin sketch ...

 

[hillbilly1]

My version...


Quote by Smart $
Note this cannot be accomplished with two 3P (3 ? NO contacts) if the reversing contactors are also the starting contactors, where L1 is also switched, because [motor] T4 is directly connected to L2 and would remain energized in the "OFF" state. So either two 4P-NO contactors are necessary or one 2P-NO starter contactor and two 2P-NO reversing contactor


It is not abnormal for motor control circuits to leave one leg hot, most reversing contactors are two three pole units. Look at a residental single phase A/C compressor, they use a single pole contactor to control a 240 volt compressor. Take note though if the reverse contactor for a single phase motor is activated while the motor is running, it will continue to run in the same direction. direction reversal is only accomplished during start up.

 

[Smart $]

It is not abnormal for motor control circuits to leave one leg hot, most reversing contactors are two three pole units. Look at a residental single phase A/C compressor, they use a single pole contactor to control a 240 volt compressor. Take note though if the reverse contactor for a single phase motor is activated while the motor is running, it will continue to run in the same direction. direction reversal is only accomplished during start up.

From a safety standpoint, I would never design a motor controller that leaves any conductor to the motor hot while in the "OFF/STOP" state. Working on or with 1? motors or motor controllers is quite rare for me, so I forget that it is a somewhat commonplace design. I believe I've never seen it done with 3? motors, yet no motor will run with only one leg energized.

 

[LarryFine]

That's what disconnects are for.

 

[benaround]

Looks like ronaldrc has what the op is looking for. nice drawing ronald !!

 

[ronaldrc]

Thanks Frank


I used as few contacts as I could get by with.
If it where my job I would use four pole contactors.

By the way all the leads coming from the motor
would be hot from backfeed even P2 which is not
used on 240 volts.

 

[Smart $]

Thanks Frank


I used as few contacts as I could get by with.
If it where my job I would use four pole contactors.

By the way all the leads coming from the motor
would be hot from backfeed even P2 which is not
used on 240 volts.

FWIW, because T2 and T3 are connected together at the motor, you only need run one conductor to the contactors for the pair. Granted, terminals at the contactor will also need to be jumpered. But only five conductors are needed from the motor to the controller.

 

[ronaldrc]

Thanks Smarts

Thats true I'm sure there is other refinements I have missed.

 

[cjphelps]

Very Good ideas, I ended up with 2 4 n.o. contactors, and 5 conductors between Motor and Cabinet.

Thank you!