G.E. Lighting Control System problem

titan1021

Senior Member
I have been asked to troubleshoot a problem with a G.E. Lighting Control System. The client says that the lights worked fine one day and the next day the switches quit working, and are stuck in a mid position between On & Off. They've had two other Electrician's look at it in the past month with no solution, the lights in this office building have now been burning 24hrs a day for over a month.
I am not familiar with this G.E. system, but I did discover relatively quickly that one of two transformers that supply control voltage in the Control Panel was extremely hot compared to the one above it. My metered showed that this particular transformer had no output voltage on the secondary side. I ordered a replacement power supply and installed it figuring there was a really good chance this was the problem, since the switches use low-voltage for control.
The problem still persists!

Hoping someone here is familiar with this system and might be able to give me some advice.

Thank you.

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iwire

Moderator
Staff member
Location
Massachusetts
First off the switches are not stuck in the mid position. That is how they should be.

They are single pole, double throw, center off, momentary.

I work on crap like this all the time, very tough to troubleshoot over the internet.

There should be small buttons up on the PC board beside each relay. Push the button, see if the relay changes state. This will help determine if the board is working.

My First guess is you have a switch that is hung up in the on position or you have field wiring that has shorted sending a continuous on signal.

Seeing as you are new to these your best bet is to download the instruction manual from the GE web site, print it out and read it.

Then while standing in front of the unit call tech support.
 

gar

Senior Member
140703-2346 EDT

titan1021:

From your photos it appears that the system uses GE RR type relays. Fundamentally the RR relay is a very useful switch.

An RR relay is a mechanically bistable mechanical switch actuated by a magnetic plunger driven by two separate coils with a common wire to the two coils. This relay being a mechanical contact type as compared to a solid-state has very low voltage drop, millivolts, with full load meaning very low power loss. No electrical control power is required to maintain the relay in either an open or closed state. Momentary energy is only required to change the relay state.

Loss of system power does not change the state of of the RR relay.

This is an ideal relay to use for complex switching applications. With simple low voltage wiring, 24 V range, any number of control points can change the state of the relay with three low voltage wires between simple SPDT spring return to center switches wired in parallel on the 3 wire bus. The switching contacts of the relay are tolerant of very large voltage transients in contrast to solid-state relays, and in the off state the leakage current thru the contacts is extremely low.

With the addition of electronic circuitry between the control switches and the RR relays all sorts of complex logic functions can be performed.

Your photos imply that that electronic circuits exist between the control switches and the relays. Either in the power supply (related to your small transformer) and/or in the electronics is the likely failure.

You could do some simple tests yourself, but iwire's suggestion to call GE is probably your starting point. Also get some instruction manuals and study them. Unless there has been continuous power applied to relay coils the majority of the relays are probably OK.

You are in a continuous lights on state because that was the last state of the relays when some failure occurred. Had some lights or other loads been off at the time of failure, then they would be off now.

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Sparky3141

Member
Location
N/A
Quick and sometimes easy checks: find your power supply for the switches- the step-down transformer that feeds the switches. Check to see you're getting the required voltage (from nameplate) out of the xformer to your switches. Physically locate low-volt wires coming from switch to the terminal board or other identified connection to relay and actuate switch while checking voltage to the relay. Sometimes there are small fuses in this circuit that can either be visually checked or pulled and ohmed out. If you can positively identify those basics of the circuitry, you might be able to pull a rabbit out of your hat. But pike the others have already stated, there is no substitute for learning the theory of operation, having the schematics in hand, and tech support on the phone. Good luck. :)


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iwire

Moderator
Staff member
Location
Massachusetts
With the addition of electronic circuitry between the control switches and the RR relays all sorts of complex logic functions can be performed.

Your photos imply that that electronic circuits exist between the control switches and the relays. Either in the power supply (related to your small transformer) and/or in the electronics is the likely failure.
Basically the unit is a processor, the switches input into the processor and depending on the programming you put in changes the function of the switches.

You can also set up automated schedules, add light sensors network this unit with others and PCs etc.

Very versatile units but unfortunately I have seen more than one bypassed because people could not figure out how to service it.

I do agree with you about the durability of the relays but the electronics are not nearly as tough. I have seen lightning take out the electronics a couple of times.
 

gar

Senior Member
140704-0740 EDT

iwire:

Electronic circuits can be designed and built today to achieve 50 year life, except possibly for the electrolytic capacitors.

From my own home experience this is not the case.

My GE double oven wall unit has a minor failure in the electronics. Probably transient voltage caused. When in its off state, which is really not off, the electronics randomly operates its beeper. Too often to tolerate. Thus, I have to turn off the breaker when the oven is not needed.

My GE microwave oven, an unrelated unit to the double oven, randomly won't work (won't start). I have to pull the plug and do a new power on reset. There are other times when the oven has completed its timed cycle, the door is opened, food removed, the door closed, and the oven starts again as a result of closing the door. Again it is necessary to pull the plug to do a new power on reset.

There is no excuse for this low quality of design.

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