Serge controller-- goes into upper limits : LUSENET : Elevator Problem Discussion : One Thread

We are working on an elevator (23 stops) with a serge controller which goes into the overhead. It may run for a week with no problem, then do it 3 times in 5 minutes. Usually a few times a day. Unit has a Texas Instruments 435 processor and a Sweo drive. We have checked the tm box, changed inputs and outputs, tightened loose connections, changed the encoder, but no help. Has anyone seen this problem? Thanks for any help. Yes, this is the same elevator as another question put in today, I'm just providing a little more info.

-- Andy Yatrofsky (, May 09, 2003


RE: Serge Controller

Andy I have not had experience with that specific controller, but have had much experience with similar problems on Microprocessor Controls & Drives. You should check out the folowing at least: - 1. You have a clean EARTH. I.e. a 16mm2 earth conductor, running straight from the Earth ROD tapping for the building, then straight to the Lift Machine Room with no breaks or connections to any other earth points or equipment along its path. The 3PHase Cable armour is not a sufficent Earth. Poor Earthing can lead to Spiking or Transient Currents in the Earth conductor, which will affect Microprocessor Controls & Drives. 2. Install transient filters / varistors, that are rated as close to the input supply as possible, across your power supply terminals for your Texas Microprocessor control. Ensure you have Mains rated 3 Phase Transient Suppression across your incomming supply. 3. Use screened armoured cable for your motor supply & connect the Earth Both ends, ensuring that this cable from the drive output is kept away, as far as possible from any control signal wiring. 4. Ensure your encoder wiring is run seperatley from your motor wiring & that the cable screen or drain wire is connected only to the controller end earth stud. 5. Ensure all mains wiring & earth connections throughout the system are secure. Earth wiring should have appropriate ferrulled ends & not just twisted around a earthing stud. 6. It would also be prudent to get your company to have someone check the power supply quality to the elevator. This is a specialist task that requires specialist instruments, but if you have verified all of the above it is worth doing before you condem the Drive Unit or the Microprocessor Controller. There may be a need for powerfactor correction or special filters may need to be installed (you could even have a faulty supply cable), This is often overlooked by companies & they just keep changing drive & controller modules, without ever finding the source of the probelm. In these cases people blame the equipment when often it is not so, the problem in many cases lies in a dirty power supply. Regards,


-- Joe Walsh (, May 11, 2003.

If the problem occurs in the up direction, final end of the hoistway, you must check the following: 1.- Static and dynamic balance 2.- Auxiliary deacceleration signals (must be fully tested). That means that even if the logic selector is not working the redundancy signals must provide a safe landing at the top floor.

Check these points...

-- ivanhoe (, October 17, 2003.

Mark the cables and the drive sheave with marker, I'll bet the cables are slipping on the driver. Seen it and it took a long time to figure out..

-- george (, October 18, 2003.

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