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/diy/ - Do It Yourself

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215665 No.215665 [Reply] [Original]

Attention, electricians of /diy/: Here I have for you a mystery.
This picture (and the others to follow) are of the switching system for the lights in my theater. See, all the houselights are on a dimming system. But the light in the middle of the place is also controlled by switches by every door. The switches are of the dual-throw momentary type. In the off state, the light is connected to the dimmer. In the on state, it's connected to the hot bus. Since there are more than 6 switches, they're all daisy-chained in parallel and connect to a system of two contactors.
This system has puzzled me. I've since figured out that the white one is mechanically-held, and it's the one that receives the switching current. That then actuates a dual-throw switch in order to reject signals for the state it is already in, and actuates the black contactor.
You'll notice that the black contactor has 8 poles (well, 10, but the ones on the bottom do nothing). 6 of these are in use, arranged in pairs of normally open and normally closed. The middle pair essentially forms a dual-throw switch (A, D, and E) which I assume actually switches the light's circuit from the hot bus to the dimmer.
But the other pairs of poles (B-C, F-G), you'll see, do nothing at all. It's a NO and an NC switch wired in series which are both actuated at the same time. So, either way, it's always going to be an open circuit.
I don't know where any of these wires connect to. The schematic is jammed up behind the live wires in the panel where I can't get at it.
What do you make of this?

>> No.215667
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>> No.215669
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>> No.215672
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215672

There are also 4 other relays in the panel. Their coils are all connected to the same control line, and they're always energized. I can't work out what they're for.

>> No.215674

technical people will occasionally come up against one of these puzzles -- they are challenging and aggravating, but not much fun. since you're the one being paid to deal with it, at least you have some motivation to do it. Us, not so much.

>> No.215684

>>215674
Being paid to do it? No, I'm doing it for fun. I'm a student of electrical engineering.

>> No.215691

oh god, an engineer. let's hope the building is well insured.

>> No.215863

I would go with low voltage switching throughout. It saves a fortune vs. copper wire, not to mention the fact that it's safer, and reduces RF/EMI.

>> No.215867

>>215863
I'm not replacing it, I'm just trying to figure it out. Plus, I'm sure the cost and labor of replacing it all (and buying new wire) would greatly offset any savings.

>> No.215869

>>215691

You act like he's a Civil.

>> No.215872
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>> No.215873

non-latching magnetic contactors are a freakin nightmare for wi-fi etc. Time to upgrade.

>> No.215878

>>215873
How can they affect wifi? It's 60hz through a coil. Maybe a pop from the spark when it breaks contact, but that's it. We've been running both wifi and 16 channels of 500mhz wireless microphones for years with no issues.

In any event, I have neither the budget nor the time to replace it. As I said, I'm a student, I've been working with this system for years, and I'm just trying to figure out how the hell it works.

>> No.216435

Anybody? I know there are electricians on this board.