Repair 3phase electric motor(Unisaw)

Hi Kerry

i would really be interested in the RPC's output at this point. i think you mentioned it worked for other motors.

dumb question what is the RPC rated for or how many HP is the motor on the RPC?
if we are trying to start a 3hp 3phase motor with a 1.5 hp RPC we will have some problems for sure.

we have basically ruled out the unisaw motor fault, the windings are not open or highly resistant, there doesn't appear to be shorts to ground.

we are pointing to controls after we determine RPC output
 
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i may be adding too much information here but you can secure the motor to a bench or a vise.
wrap a cord or small rope around the motor's output shaft.
hook single phase220/240v power to the motor Phase 1 (7,1) and phase 2 (8,2) then quickly pull the rope like a rope starter on your lawnmower.
the motor if it is good will run and will generate the third leg itself by induction. shut it down by unplugging power
 
Hi Mike,

I will try that, it's almost the same set up as my RPC. Answer to first question, I've always used the phase converter on the unisaw. The unisaw is
a 3HP motor and so is the RPC. This solution is no so SIMPLE.

Regards..............Kerry
 
I'm running out of ideas here. Maybe start checking the phase to phase voltage in the entire system, starting at the RPC, and work your way through the entire system measuring at each connection point. At some point you may have an open circuit.
 
without doing live testing here we are at an impasse .
we will have to determine whether the RPC is producing 3 phases, then the voltage between phases
before we can really go any further.

any answer at this point is speculation
 
The RPC is working , I've tried it on two other 3 Phase motors worked fine. I value living, I have a very good knowledge of electronics and electricity. I've
always have done well, but it was working on not live current. I have some fear, but let me think about it and try a few more ideas I have in mind.

Regards.............Kerry
 
do what feels comfortable to you. and don't feel the need to impress anyone.

that being said, i can assure you that it can be done with relative safety if you take a few precautions and not actually touch any bare conductors when you are hot.
your leads are insulated, and the wiring is insulated so it won't jump gaps at this voltage and try to bite an unsuspecting victim.
direct contact would be your greatest concern


any decision you make,
i'll be happy to lend a hand or explain, my thimbleful of knowledge, to you .
 
Hi Mike,

I had another 3 phase switch which worked on another 3-phase motor I tried to test the RPC, by chance I thought
to connect the switch to the Unisaw motor in question -IT WORKED!!. I suspect it was either the external switch to the Unisaw
motor or the electrical line/3-phase outlet that was non-functioning - Who would ever think?
Once again thanks for your help- Guiding me through it all- I'll know for the NEXT time.

Regards................Kerry
 
razinman said:
Hi Mike,

I had another 3 phase switch which worked on another 3-phase motor I tried to test the RPC, by chance I thought
to connect the switch to the Unisaw motor in question -IT WORKED!!. I suspect it was either the external switch to the Unisaw
motor or the electrical line/3-phase outlet that was non-functioning - Who would ever think?
Once again thanks for your help- Guiding me through it all- I'll know for the NEXT time.


Regards................Kerry
Click to expand...

hey Kerry,you are welcome.
anytime you need help shoot me a message, always happy to help out.
 
Mike,
I appreciate that , I'm sure we'll "talk" again!

Regards...............Kerry
 
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