Single Phase Brooks Compton wiring advice please

[Richard B]

I have a Brooks Compton single phase 3hp motor which has just been returned from the repair shop. This model has a start capacitor and a run capacitor. There was a note with the motor (attached) showing the connections, but I am unsure how to wire this up now.

This is in a Colchester lathe and has four wires from the switch gear, a "run" pair and a pair to set it to forward and reverse. I assume "run" is U1 (Live) and U2 (Neutral) as I had previously used, but where does the switch live and neutral go?

If the switch is to the two terminals marked "SW", that is not how it was wired up previously, but it would make sense.





All help gratefully appreciated, as they are now closed for Easter.

I may well upgrade to a 3 phase motor (as per the OE installation) and an inverter at some point, but I would like to get it running now.

 

[jimbo84]

I’ll happily be corrected but that picture doesn’t look right for a Brook, it’s from memory usually terminal designations of Z (1&2) and A (1&2) and SW terminals, do you have a picture of the actual motor and then the diagram on the back of the terminal cover?

 

[Richard B]

Unfortunately, there is not a wiring diagram on the cover, there is this commission plate. The second picture is how it was wired up previously. The two white wires are for the start (rotation direction) circuit.

 

[Brad93]

Cap Run Cap Start

You need to find your switch wires.
Then find your windings. Start and run.

 

[Guineafowl]

What’s the resistor for?

 

[Richard B]

I don't know, but I did find this information on the web, migght be relevant?

"I had to add a braking resistor to avoid over-voltage faults when decelerating from high speeds. I've run the Chippie this way for over a decade, with no problems"

 

[Pete.]

I don't know, but I did find this information on the web, migght be relevant?

"I had to add a braking resistor to avoid over-voltage faults when decelerating from high speeds. I've run the Chippie this way for over a decade, with no problems"

Not relevant that is about not faulting a vfd under braking. The resistor is for discharging the start capacitor.

 

[Guineafowl]

Not relevant that is about not faulting a vfd under braking. The resistor is for discharging the start capacitor.

Why, when it would discharge anyway once the motor spins down - maybe to reduce arcing of the switch?

 

[Pete.]

The capacitor is charged then the switch opens so the capacitor is then holding that charge. I just scrapped a similar motor with a burned winding that had the exact same arrangement.