# HOA wiring help!



## notredave (Jun 25, 2012)

I need help please. Electrical designer needing help with a wiring diagram for the following:

75hp motor, 150A HMCP breaker, an engineer speced out the MCC bucket.

Presently, there is a 30 HP motor with start/stop at the motor but client wants to upgrade motor to a 75 HP with H-O-A and make Hand go to an existing PLC. Can some one please help me with this? I have started a wiring diagram but need help to finish it. Thank you in advance. I am trying to learn and understand all at the same time. If you need anymore information, please ask. Thanks again.

http://i1295.photobucket.com/albums/b639/notredave/DG-15-330xx_zps2bb5bed7.png


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## Voyager (Mar 4, 2010)

In my opinion, the PLC should be wired to the "auto" position. Are you sure you heard the engineer correctly?


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## notredave (Jun 25, 2012)

Yes, you are correct, it will bired to the PLC in the auto position


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## Peewee0413 (Oct 18, 2012)

Common feeds the start stop. Input from off the stop button, and input off the start button. TRIAD to the HOA. One common and H/A inputs. The programmer should do the rest. Running the start/stop wire through safety devices? Was the PLC already there controlling the motor? You almost gave plenty of info, but there can be other factors.


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## RonBaggett (Jan 9, 2013)

With a PLC you can do several different things. The auto function can incorporate interlocks. The hand position can bypass some or all of the interlocks. In this case the Hand and the Auto would be wired to the PLC. The PLC output could be wired to an isolation (slave) relay to energize the contactor coil. Another way is to wire the Auto only to the PLC and wire the Hand contact to the contactor coil placing the hand contact in parallel with the slave relay contact.


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## Peewee0413 (Oct 18, 2012)

Depending on your E-Stop design, you might have play around with it. You might want indication for your e stop?


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