Wiring a relay


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Old 05-29-17, 06:36 AM
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Wiring a relay

Hello. I've been trying to wire a relay so that a photo beam sensor cuts off power to my garage door opener (to avoid damaging my car's hatch which opens really high). Essentially, I'm unsure which ports to connect to what wire. I've got the hot wire from the motor and a neutral as well as a normally closed, normally open and common from the sensor. I've tried what seemed obvious to me but nothing gives. The relay I have is below. If people could point out what to connect to what, it would be greatly appreciated! Thanks a bunch.

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Last edited by ray2047; 05-29-17 at 07:38 AM. Reason: Add cropped and enlarged image.
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Old 05-29-17, 07:02 AM
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Relay

What is the brand and model number?
 
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Old 05-29-17, 08:09 AM
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Thanks. It's an RMI series mechanical 10 Amp DPDT relay from Carlo Gavazzi. Does that help?
 
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Old 05-29-17, 08:35 AM
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DC to power the relay coil goes wires to 2 (negative) and 7 (positive). Power for the GDO comes in (source) on 1 and goes out (to GDO) on 4. Powering the relay kills power to the GDO (as does unplugging the relay from its base). The 'kickback' diode makes the coil DC only.

To be able to use the GDO if the relay or its power supply goes south, wire a very inconveniently located switch in parallel with 1 & 4. You could get creative and fashion a mechanical interlock so the switch can't be thrown unless the relay is unplugged from its base. But adding complexity also adds possible failure points.
 
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Old 05-29-17, 08:46 AM
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A relay is just an electrically powered switch. So just think of connections 1 and 4 as the connections on a regular wall switch.

Then think of the power to the relay as separate, connected to your photo beam and a DC power source. Blocking the photo beam would send DC power to the relay pins 2 and 7.

Ignore the other connections.
 
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Old 05-29-17, 01:35 PM
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Thank you both. Very helpful. One last question if I may. I've got commonly open and closed wires coming from the sensor and then a common wire. I suppose the first two are the ones that go into 2 and 7. What do I do with the common wire from the sensor?
 
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Old 05-29-17, 01:39 PM
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You have three wires from the opener.

Common
Normally open
Normally closed.

The circuit is common and normally open or common and normally closed.
You always use the common.

You would most likely use C and NO so that your relay is only active when the beam closes the circuit.


Your relay uses the same N.O. - C - N.C. setup.

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Old 05-29-17, 06:04 PM
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Thanks. The good news is, the power goes to the GDO no problem. Using the test button on the relay interrupts it. However, triggering the sensor does not cut power. I have tried to use NO and C as well NC and C as well as NC and NO to pins 2 and 7 on the relay but no luck. Any ideas?
 
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Old 05-29-17, 06:10 PM
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You have to use a power supply the same voltage as your relay coil to power the relay.

What is the relay coil voltage ?
What voltage are the sensor(s) ?
What are you using for sensors ?

Your circuit would look like this (assuming 12vdc).......

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Old 05-29-17, 07:42 PM
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The relay coil and the power supply are both 12v. I used your suggested wiring and it still doesn't work. Only thing I can see is the wires from the power supply.
Maybe I'm not using the right ones. There several wires from the power supply but only two thicker ones. A black and a blue. Which one out of these would be the positive and the negative?
 
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Old 05-29-17, 07:55 PM
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I don't know.... without a meter it's a guess. Usually DC supplies use red and black.

What kind of supply is it ?
 
 

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