Sheppard 2 speed ac elevator tripping overloadgreenspun.com : LUSENET : Elevator Problem Discussion : One Thread
We have an old 2 speed ac sheppard elevator that we have no prints for. We could use any infomation or help you can give us. It looks like there are 2 acceleration relays. R2 and R22 that are controlled by RT2 and RT22 timing relays. Does anyone know which one comes in first and what the timing is supposed to be? After the elevator has made 15 trips the U and D contacts get real hot???? Then the overload trips.
-- joe kline (firstname.lastname@example.org), July 24, 2000
Hi Joe: It would appear you have several problems. Heating in electrical circuits is almost always caused by poor connections or undersized components (undersizing on older equipment wasn't normally a problem). A loose connection on an overload can cause enough additional heating that the device will trip even if it is sized correctly, for example. Smooth acceleration was done by inserting resistors or inductors in line with the high speed windings. After a short amount of time a relay would pick and short the current limiting device out, allowing the elevator to run high speed(3-5 seconds)The current limiting device should be sized to allow the elevator to start moving a full load up. Yor customer could benefit from a conversion to vvvf control. in a mod the control only uses the high speed windings. This type of control will run as smooth as D.C. ss drive equipment. It is amazing. I've done several. Happy elevating, Fred
-- Fred Baltes (Elman101@aol.com), July 25, 2000.
Starting and running the elevator should not make the starter relay contacts get hot. (Starting resistors will get hot, but not the contacts.) Look for a loose connection or perhaps worn out contact poles in the starter relay(s). Measure the motor run current amperes. If it is higher that what it says on the nameplate look for other problems - like a dragging brake or bad bearing. DonV
-- Don Vollrath (email@example.com), July 25, 2000.
Hi, those are all good ideas..friction causes alot of problems..gear cases with no oil..thrust bearing not set right..overhed sheve dry..poor connections from your main line to your fuses need to be checked ..poor motor to gear align ment also can play apart,
good luck dan..san francisco<25years exp
-- dan w (firstname.lastname@example.org), March 07, 2003.