Home Forums General Discussion Technical Questions Circa 64 Otis MG Problem

1964 Otis.. Had on oil and grease for 9 years went to do the five year test and it would not lift the load. Left it alone due to more pressing issue's. Three weeks later it is shut down, the gov electrical switch has tripped in the up direction only. Ohm out everything and find one of the fields is open in the hoist motor. Replace it and then it will not level in the down direction without adjusting the neutral on the generator brushes. At this point it is still overspeeding in the up direction. Go through all the contacts, fingers, resistors again and decide the last option is to replace the generator.

As you can guess by this post it is still doing basically the same thing.

We are going to have to eat a lot on this one and that's ok in the end. I have to get the customer going.

Any ideas.

I will post a picture of the print.

I think you still have a motor field problem. Have you Megged the Field Coils, and Brush rigging?

Agree, that I think there may still be an issue with the motor fields, or at least some genny fields(the burning out of a motor field may have taken out others in the circuit). Have you another lift that is working to measure fields? I would check the ohms of each motor field coil disconnected( it may be unbalanced), plus the intercoils, and do the same with shunt field of the generator. The print is a little hard to see, but the GSEF( I think- above the armature loop circuit) I would check, plus the direction field(cant see what its called) on the left hand side, but should be the generator shunt field. Check for ohms, shorts to earth, for balance between up and down etc. Adjust the neutral plane to the mark on the generator and you shouldn't have to move this. Any way let us know how you go.

I still can't get over the O&G contract. The customer must be spending a small fortune to get this going again.

give me a call in the morning, what happened, did you get it to run today? I thought it would not run, are you now back to it overspeeding but at least running. talk to you tomorrow

Moving the Brush Rigging has a drastic effect on compounding strength. Depending on your Generator size 63, 71, 82GA or larger GB's or B sets an 1/8 of an inch rotation will close to double compounding strength. Against the rotation makes compounding stronger, with the rotation makes it weaker. What it sounds like is the speeds may have been adjusted with a bad Carbon Contact on one of the speed relays IE, E1A etc. The contacts get a glaze on them and have a high ohm value. Car speed will increase if the contact is changed and has a zero ohm value by sometimes 30fpm especially on a self excited main generator field. There are a lot of things to look at on a Ward Leonard closed loop system. Motor Fields, Armature Voltage, Compounding, Load Weighing, and correct switches operating. Have you measured the speeds? What is contract speed and what speeds in both directions are you getting with what voltages on Armature and Fields as to what Motor Nameplate voltages are?

I have seen this before. After checking everything in the controller, I had the generators pulled. But the cars still ran hotter up than down. Had to try and get a good film on the comm fast but I was able to tweak the neutral to be able to put the car back in service. I have seen some smart troubleshooters do this but they called it "cheating". I'll bet the old Otis wizards know what's going on. Maybe excessive heat over the years? carbon buildup? insulation breaking down? All this changes resistance...

At least if you can't give speeds, post the wiring diagram number and Generator size. Info is on generator and controller tags.

I did adjust the neutral and that got it working better for several runs but then back to the same.

Going back today. The speeds are 200fpm car. Up was 270 and down was 180. Gen type 63 GA 125 volts 18 amps. rpm 1800

108-b157052b

Disconnect feilds and feed them with 110VAC. Then messure voltage drop across each feild and see if they are equal. More than a volt are two differance can be a problem. Also as others have give good advice I have seen more overspeed in the up direction caused by load weighing than any other cause. On Otis equipment.

This idea is a good one. Also I have found that its a good idea not to get too technical from the start, as you can go around in circles. Is this a single car or in a bank? If more than 1 lift, I would check the ohms of the motor fields( as they burned out), then the same for the generator fields( shunt field, levelling field etc), then the resistance tubes(are these lift the ones with the dials?). Then compare this to another lift, which can give you a snapshot of the tuning from lift to lift, which may eliminate/or find an issue you may be having. Also I see that your lift is over speeding in the up direction by 70 fpm, and I seem to remember(rightly or wrongly) that tuners used to want a slightly less fpm in the up direction than the down, purely to eliminate the possibility of over speeding occurring due to the counterweight pulling the car down. Measure your speeds, chocking out 1E etc, as you may find which speed is out of whack. Also I would make sure that your not getting a very small short to earth on up main contactors which can also give you a out of compounding effect, however unlikely.

Might sound stupid, but check the ground wire from gen.

I stay clear of brush adjusting, if the car ran great before and the brush rigging has not been jacked with, dont mess with it. As the previous poster added, check the entire loop circuit for isolation from ground to start with-then meg the loop circuit.

looked at a base B1S7052B diagram and this is an 11-23 UCL controller. This was a bread and butter controller for Otis. It has in the loop circuit the current sense relays VR(set to pick at 1/2 Motor Armature Volts) and XQ (Positive Load) which picks Q and raises Gen Field Volts. Make sure Q is not picked in the Empty Car UP Run. It is also a self excited Gen field which is started building by The induction in the Generator from the leveling Field. The Carbon Contacts OHM value will greatly increase or decrease car speed if it was adjusted with a bad contact.

Also if you have Condenser Dampening, make sure CND relay is in the up direction and out in down. It is a SET-RESET relay.

Also check your series field tap setting are similar from lift to lift.

E-man,
I found an old write up that spoke of the hertz surface that builds up on the commutator you spoke off. It describes two methods in which to accelerate the hertz surface layer.

1) use pine wood to burnish the commutator.
2) use a very light layer of commutator oil applied by a rag or cloth.

Solidstate,
I looked through some old papers. There was three items I found for overspeeding.

1) load compensation switches
2) contacts such as H
3) motor field deterioration

Please let us know how you are making out...

Uppo.. it is a single car.

At this point.. I would love to be back to the over speeding problem!! I have been battling with the new generator set up that seems to be a never ending night mare. Here is what it is doing now.

The unit will run fine in the up direction with out over speeding.( Have not put a tach on it but it does not trip the gov. switch)
When you put in a down call the gen loads up and wants to shut down, and the motor stops turning. It burned up the DF Coil in the leveling field, I assume because I didn't kill the power in time. I am getting the same field motor voltage and armature voltage in both directions as well as the same GLF voltage to the gen.

It will run down on inspect and if you run it up on inspect the motor at first jumps a couple of times and then smooths out.

On automatic if I block out the speed switches(which I assume is blocking the loop circuit of GF and GF1) and put in a call it will run down on slow speed until it comes in to the called floor and then will not level in. Talking to the motor shop he suggested I swap GSF and GSF1. Tried that.. no avail. He then suggested to swap GA and GSF around and it tried to load up without a call on it. The last suggestion he gave was to hook up GSF2(which is not hooked up to anything) in the place of GSF1 and leave GSF1 unhooked. This did not make any difference.

Thanks to everybody for your suggestions and help.

this may be a silly question, and I am sure you checked, but are you picking the brake in the down direction. Also if the commutator looks like a new penny, let it run a while and get a glaze built up. Empty car up the counter weights are helping you, empty down you are picking a load. I would get the motor shop to get someone on site to make sure the Genny fields are wired properly.Don't discount the Motor fields, you may still have an issue there.

No silly questions at this point. As we all know it will come down to some silly overlook or discounted notion.

The brake is picking.