Re: need help rotophase
Here is the scenario for the "Roto-Phase" Add-a-Phase, Phase converter. I recently troubleshot a client's call for help involving their roto phase which let the magic smoke out. The old one was not happy and a replacement was installed, however this replacement was a re-built phase converter which was in a clean condition, owned by the client, but had been sitting for 15 years without operating. In my experience capacitors do not like to sit that long without being energized. The phase convertor had been wrapped in plastic and protected. It was located in a farm shed but not totally protected from moisture, condensation etc.
To continue, the replacement unit was installed and I advised the customer he should be aware there could be a failure of the capacitor bank. A couple of days goes by and then I get a call. A motor fed by this phase convertor began tripping the overloads on its controller.
I checked the amperage draw of the motor and found the following Tested from the load side of the motor controller : 240v 3 phase, abotu 1 hp motor runnign hydraulinc fluid pump T1- 4.8 amps , T-2 12.6, T-3- 10.8 amps. The overloads kept tripping and had to be reset.
To rule out this motor , I went to another motor (different circuit) and tested it underload. The results were the same imbalance as the other motor. I did not think it was the motor.
I advised the client the only variable that had been changed in the whole conveyor system was the add-a-phase and recommended replacement of the add-a- phase most recently installed.
A couple of days went by and I called the customer as a follow up and he had advised me he had called another electrician and had them check it out. This electrician said he did not think it was the add-a-pause and thought it was the overloads of the motor. I did not agree with this as the rule out factor of testing the second motor with the same imbalance leads me to beilieve the add-a-phase is the guilty party.
This electrician attempted to increase the setting of the overloads with no success. I still think because of the currrent inmbalance the overloads are tripping.
I guess the question arises , how is the current unbalanced as it feeds the motor through the phase converter if the capacitor bank has failed.
If you would like to discusss this via telelphone please give me a call, Thank you for your replies. Dan
{Moderator's Note: Edited to remove personal contact information. If you wish to contact this person, please send a Private Message.}
[ June 27, 2005, 10:02 AM: Message edited by: charlie b ]