Home Forums General Discussion Technical Questions Otis 21NIC1 Down leveling issue

2 speed car. Up direction works fine. Down direction I lose my DG going into leveling. On my print I show my DG coil in area 6, but when I go to the relay glossary, it shows the coil to be in area 6 and 7, and I do not have an area 7. If I force DG in car goes into leveling flawlessly. Im only seeing a few auxillarys in front of DG coil, UD n/o 3/4, 1A no 13/14, and a DG resistor and DG no 7/8. I have changed the contacts on each of those along with the resistor.

Is there a down direction timer I am missing? Controller wiring diagram shows RX9-3S7021C and RX1-2S7592J on the data tag. Closest prints I have are RX2-4S7021C. I have contacted UNITEC and they do not have my exact print, but refer me to the RX2 print I have. They also told me some more interesting info, as the serial number 33267 and sales number 653153 show this elevator to be installed in Canada. We are far from Canada. This is in a power plant in Central Texas.

How are the leveling speeds? Is up faster by a couple of fpm? Compounding might be off. Anti Stall timer might tripping as a result.

I think this is a 2 speed AC unit, so compounding would not be a factor. Having no print is a problem. You might want to put a balance load on the car and see what the leveling speed between up and down is. I would look at the motor, brake, incoming power, and those related contactors. Good Luck.

Is'nt DG the gate relay? If there is a secondary (double wound) coil, there would have to be directional contacts in that circuit.. First, look at DG and see if it is a double wound coil. Maybe preopening is having a problem.

2 speed AC. DG is direction holding relay. Horrible use of DG as a designation of direction holding in my opinion...

After searching numerous similar prints I have found the other area I mentioned. This is in fact a double wound coil. The other area shows it to be with the leveling switches, and its listed as "buck-out" The leveling switches are DPDT. I have ordered rebuild kits for them. These are explosion proof switches so replacement switches are many weeks out. Once rebuilt I am hoping the problem is fixed. Job is around 4 hours away.

From what I can decipher, once the car hits my down leveling, a set of NO contacts on my down leveling switch, (or perhaps on my up leveling switch) are hitting prematurely causing my DG to "buck-out".

I actually got out one of my old books from NEIEP that had buck-out listed. That term isn't exactly used in modern elevators now days. This is my last OTIS at this facility, hoping to be modding next year.

I have a variety of controls on this job site.

Galaxy, Otis, Miprom21(recently modded), EC, ESCO, GAL Relay Logic, and Miprom 1's. Along with 5 rack and pinions (Alimak and Champion)

Update. Car is back up and running. Down leveling switch was the culprit. Rebuilt and good as new.

Word to the wise, if they are the ex proof switches, be sure and put the same cover that came off, back on. They are milled individually and have minor differences although they look identical.