Home Forums General Discussion Technical Questions Motion Control "MLT" fault

Motion Control hydro, 2 stop has "MLT" every day
Can you guys give me some direction to go in.. I know it's a motor limit/valve fault. I bumped the MLT timer parameter up a bit with no luck. The elevator seems to getting to the distination in plenty of time? I'm clueless

Check to see if it's hitting top normal limit.

Ok. Thanks for the quick feed back!!
Any other suggestions? I checked contactor and it needs to be replaced. I didmt figure that is the issue. But it's going to get replaced as well

Check your motor contactor and AUX relays to.
You might be hitting top normal limit while in leveling.

10-4. Thanks a ton guys

Is your oil cold?

No sir..machine room is in climate controlled area. Never gets under 60 or 70.

MLT will occur any time the computer sees the up direction input (input UPS) "on" for longer than the MLT timer is set for (1 to 6 minutes). The motor may not even be running in some cases. On both the old HMC1000's (green boards) and the newer Motion 2000 (red boards) there is a feature called the MLT/VLT data trap. The computer will record all of the data flags (inputs and outputs that are on when it records the latest MLT or VLT fault. Flip F2 dipswitch up, to select external memory, enter in the various hex addresses given in the data trap memory chart, and and you will see what flags are on or off when the last MLT was recorded. Procedure is on page 6-76 to 6-77 of the Motion 2000 manual with a chart of all of the inputs for the bits for each hex address.

All that being said, I had one that would MLT because the car would move up when the pump was recirculating oil during viscosity control. Maxton valve bypass wasn't adjusted properly.

I also had one that would intermittently give me a VLT due to a bad door zone wire connection, so the car would start to level down and not see door zone and then keep leveling down until it hit the down direction limit switch.

Also on the old green board motions had one with bad UP relay contacts. If I remember correctly the pump would be running in bypass, but the up and up slow valve coils weren't getting voltage due to relay contact failure. Could also be "H" relay contact failure not energizing the up fast valve coil and intermittently leveling all of the way up.

http://www.mceinc.com/products/manuals/WebManuals/HMC-PHC%20ASME%202000%20(42-02-1P01%20Rev%20C2).pdf

Also MLT/VLT data trap procedure is on page 6-23 of the old hydro manual.

http://www.mceinc.com/products/manuals/WebManuals/Motion_2000_Hydraulic_V9_42-02-1P21_A9.pdf

Both manuals available from their website, see links. Good luck!

Good info guys! ! MANY THANKS

maybe a failing slowdown switch?

Or-

If a Maxton UC4 valve, be sure the F/S adjuster is on the dot/scribe line, and that the three allen bolts are tight. If you increase UL only to have it change (i.e. slower fpm from when a previous adjustment was made), its that FS adjuster.
However, Snrkheads suggestion on the upstop limit is a very good one. Check your limit on access, and the car better stop at least 1" above FL. If it stops even with the landing, raise the limit switch 1/2" and recheck.

Other ideas would be burnt contracts LU,LD or H relays.

Those commonly used LS1 switches (if used on your job) are trash in my opinion. I see them a lot on MCE jobs. Seems every job that uses them, the stationary contacts need to be bent upwards a tad for reliable contact operation. Read that to be MLT or "Down Limit Failure" if the car fails at an upper floor.

The data trap is lifesaver for these situations. Print out a few copies, the up sense input is a good place to start after you have the data recorded. You could hardly even list all the contacts and scenarios that can cause an MLT but if it seems like it's happening every night, make sure you Manual lower it and force a re-level several times. It is possible the valve could struggle to start with only the slow valve picked.

MANY thanks guys!!
I learned alot from the suggestions.
I checked hoistway switches.
Replaced contactor. Replaced relays. Etc... then after a couple hours. BAM
it went to 2nd floor and stayed in up leving without moving and tripped MLT!!
I adjusted valve. And found S/F allen bolts loose!! Tighten bolts fined tuned valve.(it was WAAY to fast in the up)
2nd day and no issues.. recommended a new valve anyway. 10 yrs old. Thanks again guys!!!

Hopefully it's out of your hair for good. This is yet another great example of what the forum is designed to do, and I hope we're not premature in extending congratulations to you.

Dear friends. I have a imc ac control . Daily we are facing one problem. One lift when is going to long travel it has been stopped for each floor leveling without door open while normal operation . Anybody’s can help me. Please

Issa,
Welcome to the forum.

If the car seems to run on automatic, leveling properly etc., look for the DOF input to turn ON using the CRT screen if there is one. If no screen is available, you’ll have to utilize the CPU flipdip switches to access the address for this input. The manual shows how to do this. If the car lands properly and is NOT faulted, and you don’t loose DLK on your CPU, then your doors aren’t opening. Most common is for the Door Open relay circuit to fail regardless of door controller make. Whether MAC or MCE, door pilot relay contact failure is common. If the equipment uses the GAL MOVFR type door controller, again, look for the DOF input either on or off. If the car runs normally on Independant, with no door trouble, and this is a “Group” operation, check that all cars ID and LABEL match. Car 1 must be car one, and car 2 must be two both in LABEL and ID etc.

FYI- When an original first time post is made, start a new thread. It will get more views.

Thank you friend. . I was checked in the group panel for DOF setting but I couldn’t found . Kindly let me where is it. Swing panel or group crt. Door open Front (DOF) this is right. I have a manual. But there is no any problem about this issue.
So kindly help me please.
I was already send new Thread .
Thank you

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