Home Forums General Discussion Technical Questions 1956 Otis relay logic

This is an old lift. Has developed a new problem. In our 35yrs of servicing it, it has never been reocrded on our logs. Or any of our other similar age elevators. Here is the problem.

Down direction only. When called to the 1st landing either by 1C or 1U. The elevator will respond but never goes into high speed. Not a weak coil or shot coil because it works just fine in the up. Tests show no voltage/current flow happening across coil so it is not even trying to come in. This is issue 1.
Issue 2. When it finally gets down to 1st landing it stops about 5ft above the floor on its own. Kicking out all the run relays. But never the call relay. Generator times out and it shuts down. You then give it a call to any of the upper floors and it fires up answers those calls but because of the still latched 1C or 1U it trys to return to 1st landing. And is stuck again. The elevator stops at all other floors just fine , albeit slow in the down direction, except the 1st floor. It won't even run down to floor level on inspection.

The selector is a piano string drum, screw gear vertical carriage with ski's and buttons. I have checked all the ski's and buttons and toned the wiring. All ok.

Have checked top and bottom Hoistway switches. Ok
Have checked leveling switches. Ok
Have checked the car top LU DZ LD old ass giant MAG switches. Ok.

Motor and generator brushes all good. Armature clean copper on both.

Old original resistors, caps, shunts, TR black boxes and relays.

Vintage type that it has the analog voltage meter built into the black asbestos control panel. Sitting IDLE at 120vdc dropping under relay demands and load to around 90vdc..

I have been speculating that Otis coils have a way of causing a voltage drop without actually burning up. Like the older the coil it now needs 130v to work vs the original 110v. Anyway that is side note.

I am running out of ideas. Anyone? I just feel I am missing something.

Are the acceleration relays coming in? what is the controller type?

What is the controller number and wiring diagram on the controller tag? The tag could possibly be on a controller metal cover. Hope it did not get thrown away if it is on a cover.

Controller number 230832.

We have been using an incomplete print 156363AP. Not having much success.

Type off tag is what you need.

Serial number 132276
Sales number 230832
Type 20UCL
Wire diagram 1S6363AP

It apears to be related to bad carbon brushes on the motor. Not wearing right. Building up in the comutator groves. We have started re cleaning the holders and posts and we are getting our high speed back now.

Good find. you need a 20UCL print. they are pretty easy to come by.

A grounded loop circuit will definitely affect your ability to run an empty car down.

Well the highspeed lasted for a few days. Problem is back. Having a problem with Voltage drop still. Anyone know how to get more voltage in the circuit across relays? It's dropping from 110 to around 83... Relays just dont have enough power to come in..

Ironically this elevator has a sister. Same vintage controller etc. And it is having the same voltage issue just inverted. It will not go into High speed up. Actually wont activate any of the acceleration relays up. Works fine in the down. Same voltage drop issue. 110 idle. Relay demand dropping to just above 85... Any ideas guys?

You have a bad 3 phase selenium rectifier. They have solid state replacements, but if the voltage goes up so does some other things. You should have between 125-130vdc. Solid state may change it to about 140 and you would need to change transformer taps to correct it.

Bad rectifiers causing voltage drop? Like I said once it gets multiple relays power is dropping.. I will take a look at those in morning.

Sent you a 20U Adjustment Procedure with some diagrams

Thank you. You are amazing

Seem to remember that there was a plate on the controllers with the last rectifier reading, so as to keep tabs on the control voltage.

As those old rectifiers go bad the DC voltage drops and they start passing more AC that causes a bucking effect on your coils making it harder and harder for them to pick. On newer solid state controllers you will see it lock up or cause all inputs / outputs to fire. I learner a long time ago to take voltage readings AC and DC and write them down. So you may read 120VDC with 2VAC. Then when you start getting weird problems you have a base line to start from. But rectifiers and power supplies will drive you crazey till you get ahead of them and know what they read when everything was normal. Good Luck

if you ever need parts for these old Otis units try Master Elevator Components, they have a lot of parts for the 1950's and before.
www.masterelevator.net

I had a similar issue a few years back and it ended up being a bad interpole on motor. Maybe start checking your loop circuit.