Home Forums General Discussion Technical Questions MCE VFMC-1000

I'm having an intermittent problem. Today was the 3rd time in 2 months I found this car tripped the overload. The first two times it was the mechanical on the PM relay. After the second time I enabled the motor overload in the drive and bumped the mechanical overload up 10%. Today I found OL1 on the drive. I reset the drive and put in a up car call. We had direction and PM picked up. But before I could check the brake, OL1 tripped. Since then I've ran the car in test without tripping.

Has anyone had a simulacrum issue?

I've megged the motor.
Checked the motor and brake wiring.
Checked the PM and BR contractors.
Rang out the brake circuit.
Checked the rail guides.
Checked the hoist machine and defector sheave bearings for heat or noise.
Checked my running amps in both directions.

Sounds like PM is single phasing
I know you said you checked it though

Building taking a power hit??
Emergency generator???

Bad BD relay?

I have tons of problems with PM contactors on mce cars especially with the aux contacts on them. I believe theres is an input to the drive based on those aux contacts on the PM contactor. Try to duplicate the fault by pulling one of those input wires off of the aux contacts and see what fault pops up when the PM contactor engages. This problem sounds familiar. I'm sure your brake pick and hold is good. The single phasing is possible but I doubt You would here our favorite humming sound. Also dont trust your meter on ohms w/o power on reading those aux contacts its all about the load those contacts can handle when engaged. Good luck.

Just a suggestion, try loosening and re - tightening all the drive connections. Had a mce with a hpv 900 drive do similar things. One of the phase wire lugs seemed tight enough, but the wire welded itself to the loose lug.

Thank you for your suggestions gents.

I'm babysitting the unit for the second day. Wahoo!

Postal, I was able to see all 3 phases before trying to check the brake. That was my initial thought as well. Great minds think alike. :-)

Sccjr, I lifted B1 and boy does it seen familiar... I'm replacing all of the aux contacts tomorrow after I pick them up. They are showing signs of wear.
Always great advise not to trust the ohm (continuity) readings of a meter. I prefer reading voltage myself. Checking the voltage drop has served me well.

Galaxy, I'll check it out thanks...

Thanks again,

Turned out to be the BR relay. #3 BR contact in the brake coil circuit would fail with no pattern or rhythm. Some times it would be weeks before it would fail. Finally I pulled the relay off the controller and opened the coil & armature up. When I did some debris fell and hit my foot. Looking at the contacts there is some burn. But there is a needle like tip formed on the contact. As if the contact metal heated up and was drawn the follow the arch across the contacts. I'll post a picture if I can figure out how.

Thanks again Brett for you suggestions. Your a good Mate...

No probs JKH. Glad to help in any way. When a main switch trips its nearly always a brake issue and a inrush overload on a vf drive is probably similar thing and good to remember.