Good morning fellow elevator techs. Before you jump to conclusions about me burning out 4 hydro motors on an MCE (HMC-1000) read what I tested, replaced and checked and see if you have any ideas. I don’t think I am a total [censored] but if someone can prove me wrong, I’ll be happy to admit it.
duplex 4 stop MCE controllers with Wye/start delta run relays 480VAC/3ph 40HP high voltage motor (wired correctly) 200-amp breaker in the electrical room both controllers are fed from the same buss bars in the main power breaker room 100 fuses in the disconnect switch
1st motor: Went to the job found 200-amp circuit breaker tripped in the electrical room (didn’t blow fuses or trip my overload) then found the original motor shorted replaced the motor, checked main line relays, voltage, wiring amped motor. all checked good. Thought the motor just went bad due to age since nothing was found to be bad. Checked the motor start/run relays and they were binding (Aromart contactor but were not getting stuck in or binding at all) 2nd motor: Went to the job same thing (200 amp breaker tripped) checked overload, fuses and tested motor, found motor burnt out. I was told that the only thing causing this would be the start/run relay hanging up. So, we replaced the motor, overload start and run relay. Wired up (triple checked the wiring) and its good. Amped the motor after the install inrush was like 135amps +-10% from line to line running amps was 35amps +-5%. 3rd motor: Went to the job same thing (200-amp breaker tripped) checked overload, fuses and tested motor. motor shorted internally (winding shorted together). I start thinking my breaker is bad (since its always tripping). I switch the breakers in the electrical room. Installed an overload when L1,L2,L3 come into the controller and set low (like 30amps) in addition to the motor overload that still hasn’t tripped. Megged the wires from the electrical room to the disconnect switch, from the disconnect switch to the controller, from the controller to the motor. Everything reads 600+MEG ohms ~ohms. Hook up the new motor myself (it was previously wired by another mechanic but it was wired correctly). I call MCE to see what they think and they tell me the problem is not from the controller. Hooked up a camera system to watch the elevator run and left the car running. 1 week later we get the call the car is shut down. AGAIN, level at the floor breaker is tripped 4th motor:
Boss sends a team back with a 50hp motor (motor shop told him the lead ins are breaking due to amps/single phasing) I tell him the 50hp can hurt us because of inrush current (but he’s the boss) not to mention the contacts aren’t sized for a 50HP motor. Call up MCE get a soft start (this supposed to help see the issue) . Go to the job install everything, set the settings of the soft start to below name tag. Installed the New MCE relay board that came with the soft start and 4 days later the car shuts down. Level at the 1st floor and the camera shows the car sitting there with custom loading basic house hold items in the elevator. Customer Goes to their car to get more, the doors close and the elevator relevels, the elevator levels up and boom its off.
Here we are today (2/2019) I see that the windings that are shorting are the ones getting power straight from L1L2L3 jumped to the fault contact. ( ill attach a pg of the print) So the windings coming out the t456 of the fault contact is shorting. This is the same case as the start/run relays we swapped out. Almost like the motor is cooking while sitting there not running (but fault contactor is fired all the time as it should be). I am not an electrical engineer but I can only see it being one of two things (and I know the one is a reach).
1 Wiring from the electrical room to the controller (including the disconnect) is intermittently grounding or shorting. I plan on switching the controller feeds and hope the issue switched from car B to car A. The Meg test I did earlier should of picked up on any insolation issues within the wires and disconnect switch. 2 Small transformer on the controller. Off on L1L2 there is a transformer that takes the 480 and drops it to 208 and 120. If somehow this is breaking down and shorting internally, I thought maybe it’s putting high voltage. IDK it’s a reach but I am completely out of ideas on this.
Now 5th motor is ordered and soon I’ll go with a lighter and can off gas and just burn it myself
If you have any ideas or insight please let me know.
If u can get something to monitor power to machine room that would be smart,had a job burn up 2 motors in a year and the 2nd one 2 wks before the full service contract ended.kone took it over and burned 2 motors also,they changed starters, pumps,and the valve only to find incoming voltage was fluctuating.
Wow. I think the only thing left is the disconnect and/or fuses. Do you read any resistance across any of the fuses? You have to be losing a leg somewhere. I don’t think a ground would cause this. I would definitely get a 3 phase voltage monitor on it. You might be able to catch something at the disconnect with a meter set to Max from line to load, one phase at a time. Any resistance will show up as a voltage drop.
What brand Soft start did you install? Do you know if the incomming power wires would shake inside the conduit when the motor starts? There may be a wire shorting in the pipe on start up.
I installed a phase monitor so if the voltage goes to low/high/missing it should trip. Do you know of any line monitor systems? Both elevators share buss bars in the electrical room so I feel it should be a power issue with both cars not just the one. This is also why I will be swapping the L1L2L3 connection at the controllers and trying to get the problem to switch cars. This still wont answer why its happening though. I run the car all day with meter and amp probe and looking at the soft start power but everything looks in order. Lowest voltage I see is 479Vac. With a difference of 7-10V between lines
I feel the meg test should of picked up on any insolation breakdown of the wire within the pipe. Again this is why I am switching power feeds at the controller on motor 5. I shook the crap out of the wires, shake the pipe, stuck my screwdriver in there and twisted.
phase monitor was installed motor 2 or 3 settings for low/high and std missing should trip it out. I don't even see the light flicker on the camera when this happens or before.
Since the units are in the same bus, swells might be occurring internally or harmonics is a possibility. Root cause might be 1) old hydraulic fluid (a slight change(increase) of viscosity can result to increase in pumping load) like a hypertension 2) clogged plunger,valve or hydraulic line, uncalibrated pressure sensors/switches and guages 3) pump issues, like failing bearing or misalignment, or worn impellers 4) Failing Drives (IGBT's tend to short circuit when failing. 3 line has each own set of IGBT's if one is failing its additional load to both remaining)
I would rather recommend owners to isolate each motor/lift with an AVR plus a surge protector. By that, I can be sure that power supply quality is not the issue since harmonics and swells can be directly eliminated with its aid. AVR won't cost much than a burnt motor or control board or drive to replace.
I have no problem with my previous installations I have with AVR, the only sad thing is you don't have much electronic parts to sell cause it does prolong pcb and sensor life. For eight years I have not even changed an LED lights of the cabin. Only mechanical parts.
It would point to a phase loss, but does not have to be incoming power. The last situation we had was a piece of wiring insulation was not stripped all the way back on a new drive to the contactor. The resulting phase loss, opened a coil on the motor and the drive started faulting out. It took a good two days to find it. Of course it seems you would have eliminated all of this by replacing the wye delta with soft stater.
I even did one better by cutting all connections and re-stripping them and reinstalling. This was done in the main electrical room, disconnect switch and all controller connections.
No way it could cook a motor that quick without blowing overload if its a short. Logic says phase loss. But how has nobody stuck a laptop on this thing yet? To record incoming and controller side voltages/amperage. Would've done that after motor #2. Company must be made of money to do all that work without testing. Did you replace valve? Could it be getting down section stuck open, constantly releveling? I'd pull valve apart and be sure.
