Otis 411 - Ward Leonard Control Early 90s Vintage

I have 12 of these cars and some of them log several F/B IST faults throughout the day. It shows in the manual that this is caused by the brake or motor field exceeding 180% of their rated current. Visually, all brake and motor field connections look good and meter correctly. All parameters are set the same as the other cars that don't get this fault.
The fault doesn't shut the cars down but I'd like to get to the root of why it logs the fault. Any ideas that might lead to a solution?

411 mm/s or e411? magnetek drive? which machine? any other faults in MCSS?

These are E411 with Ward Leonard (DBSS, DBSS Interface, Hall/Relay Board). Gearless machines, forgot which model. No other faults on MCSS. SPPT for position feedback.

I've only seen one of these with W/L control. Possibly compare field ohmage amongst cars to check for shorted MF windings. Just a thought.

hey GP what's the difference between 411mm/s and the e411?

I've only seen a mcs 411.

If memory serves me correctly, the ward leonard version was called a 411 MV. Closed loop generator field control. Rest of it standard 411. I've only seen one in 33 years. I believe it was sold as an option back when the great debate over drives vs. generators was going on.

The debate is over and drives win.... But we can still rebuild 40 year old generators but now it seems when drives go obsolete the majors are no longer engineering retro fits and software updates....customers lose..

I Believe the E311/E411..as they call was the Hybrid system..had the 1M/2M drive contactors..with DBSS drive board mounted on the side of the cabinet had main cards Cpu,Ring,Mcss,MCSSB..pc boards as well as a smart spt...on board diagnostics was very limited as compared to the new version 411m....

Ah right. I've only seen the normal 411 mcs control with electronic drive.

Our old company had its own version of electronic control(miprologic/miprostar), who some conspiracy theorists have suggested was the base idea behind the 401 lift, have made a generator type as well and was an ok product as it provided a better straight line dc supply than you get from scr's.

From what I've seen is original OEM drives parts are available. It's when the OEM's went to 3rd party vendors (Allen Bradley, Robicon, Louis Allis, Baldor, etc) is when obsolecense comes in the form of the 3rd party vendor deciding to obsolece a drive.

Maybe the one exception is Magnatek with the DSD 412 and the HPV 900. Both been in production for about 20 years and are in use by multiple elevator companies. Of course that was after Magnatek absorbed Louis Allis, and Robicon.

From a repair standpoint, I'd much rather carry an SCR to the machine room for replacement thant haul a 2000 lb generator up and down the stairs. Oh my aching back...

Just a thought if a brake lining is touching somewhere on the brake pulley,as the day goes on the pulley slowly heats up and expands so more and more lining touches the pulley causing the motor to draw more amps.

I Have to agree..might want to monitor the brake data..to see if brake is sagging in operation..brake power supply was upgraded to more dependable unit...just a thought...