Motor or Pump Application Error?greenspun.com : LUSENET : Elevator Problem Discussion : One Thread
For some reason on one of the hydraulic elevators we maintain there is excessive arcing during wye-delta starting on the delta contacts. A peculiar thing is that this arcing occurs about every other time and not everytime. We checked the starter ratings and although a little undersized a lot of the elevators we maintain also have an undersized starter without this problem of excessive arcing. Would someone be able to help? Our contacts here are burning out every two months!!!
-- Noel T (email@example.com), January 10, 2005
Is this a 6 or 12 wire motor?, get an ampmeter and check each wire to see if amperage is balanced when starting and running, should be prety close to each other. Did you just change this motor or has it been online for sometime.? Jim
-- Jim (firstname.lastname@example.org), January 10, 2005.
If you have similar units in service, you could compare running currents. Also check to see if the oil pressure is high. The problem may be the pump bearings.
-- John (email@example.com), January 11, 2005.
Noel, Trip the over-load so you have total control of the starters. Now, with one hand, manually engage the wye contactor, wait a sec, then with the same hand let go of wye and engage delta. Now look for "excessive" arcing. Do not remove arc shields, ever. If you don't see any, disconnect the wye coil and reset the o-load. Run the elevator making sure the valve coils don't energize until the starter picks. You may be seeing some wye-delta overlap. P.S. While manually operating the starters the elevator should not move at all. P.S.S. With a good peak reading ammeter you'll find the in-rush current on wye is vurtually the same as delta. Usually between 300 and 600 amps for a standard 30-50 H.P. motor. Hat
-- Hat (firstname.lastname@example.org), January 12, 2005.