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by **coyttl** on Mon Feb 11, 2013 8:46 pm

Aargh. Maybe I'm too tired to make sense of it all.. or maybe I'm just getting older and can't think straight. Maybe both.

Anyways, I have an Econolite 16-phase (12-phase + ped) backpanel. It as 2 flasher sockets, 1 small 24v relay, 1 small CMU sensor relay, and 6 flasher relays.

My cabinet has a 'Signals' ON/OFF switch.

When the switch is ON, the +24v relay is powered on. +24v goes to the load switches, and all work as expected.

When the switch is OFF, the +24v relay is off. The loadswitches go dark, the flasher relays stay active. All lights go dark, as is expected.

What's NOT expected is that if I manually activate the +24v relay (there's a manual physical button on the relay to activate the leads inside), the loadswitches power up and show their signals. This is as expected, too. However - what's NOT expected is that the signals do NOT light up.

I now this sounds stupid, but something is still not giving 120v to the signals, and I don't know what.

Flasher relays are still active, and flashers are still putting out 120v. If I connect a bulb up to one of the flashers, it will flash.

I can't find another relay with leads large enough to handle the entire cabinet's signals. And it has to be large, as one of the signal power wires at the entrance to the backpanel is 14 gauge, and it's blackened from heat.

Am I going blind? To top it off, I realized that with only 6 flasher relays, that means that 12 signal phases go to flash. The other 4? Likely the PEDs. However, without relays, SOMETHING has to cut the power to the peds, and there's no relays to handle those.

Thoughts? Or should I just go check myself in? :)

by **2070** on Mon Feb 11, 2013 9:36 pm

The mercury contactor is powered by the 24 volts. Where is that???

by **TacomaJoe** on Mon Feb 11, 2013 9:40 pm

AC power to the loadswitches usually is run through a 60A mercury contactor. There is probably another contact path that controls it. The lights on the loadswitches are most likely on the input side showing the controller connections but without the AC feeding the loadswitches, there is nothing to switch.

6 flash relays is correct. 8 circuits for veh phases and 4 for overlaps. Peds don't operate during flash so they don't need a transfer circuit.

by **coyttl** on Tue Feb 12, 2013 12:42 pm

Thanks guys -
I'm familiar with the smaller, glass-bulb mercury switches (that detect pitch or vertical/horizontal), I'm not familiar with the ones that .. require power to operate? :scratch:

What does one of these look like? I'm guessing it's in my power supply, then.. but not sure which one of those silver or black things it would be.. :)

by **TacomaJoe** on Tue Feb 12, 2013 2:43 pm

Here's a shot of one in my EF70 cabinet.

They typically have a cylinder with lugs for the main power (60A capacity) on each end. Around the cyclinder will be a 120VAC coil the energizes to operate the relay. The one in the photo has both main lugs on the top end of the cylinder but you get the general idea. Usually they are on the power panel alongside the breakers and line filter.

by **coyttl** on Tue Feb 12, 2013 2:54 pm

Aah! Okay, there is a cylinder-looking thing on my power panel. When I get home tonight, I'll take a look at it more closely. Thanks! :)

by **TacomaJoe** on Tue Feb 12, 2013 5:41 pm

I might also point out that gravity plays a role in the operation of a mercury contactor and they don't work laying on a table, they need to be vertical.

This one with the glass tube makes it easy to see the mercury. When the coil energizes, the metal plug gets sucked down, raising the level of the mercury to complete the circuit. When de-energized the plug floats on top of the mercury. Laying on its side the mercury won't get to the contacts.

by **coyttl** on Tue Feb 12, 2013 9:26 pm

TacomaJoe wrote:I might also point out that gravity plays a role in the operation of a mercury contactor and they don't work laying on a table, they need to be vertical.

Yeah - my mercury switch knowledge is/was limited to the little two-lead glass bulbs. As long as the switch was upright, the mercury in it made a circuit. Tilt it enough, and the mercury left one of the leads, breaking the circuit.

I THINK I found the one in my cabinet. It's huge - about 4 inches long. Has large black leads from the top and bottom, and along the side has a smaller white and black lead. :thumbsup:

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