When fire alarm energizes needs to power 2 contactors

[ee1]

When my fire alarm is energized, I have two contractors that need to be energized. I have 2 sets of relays both with a set of dry contacts. One contactor is suposed to turn on some lights and the other is to shut off some plugs. I have the dry contacts for the lights wired as normally open, so when energized the contactor should pull in. I have the other set of contacts wired as normally closed so when energized the contactor should release.

My coil on my contactor is 24v

When the alarm is energized should I have 24v on both sets of dry contacts?

Should my coil on my contactor be 24v?

 

[GoldDigger]

When my fire alarm is energized, I have two contractors that need to be energized. I have 2 sets of relays both with a set of dry contacts. One contactor is suposed to turn on some lights and the other is to shut off some plugs. I have the dry contacts for the lights wired as normally open, so when energized the contactor should pull in. I have the other set of contacts wired as normally closed so when energized the contactor should release.

My coil on my contactor is 24v

When the alarm is energized should I have 24v on both sets of dry contacts?

Should my coil on my contactor be 24v?

Maybe a problem with the terminology here. "Dry contacts" usually means contacts which are isolated, not connected (as the relay comes from the box) to any source of power or ground.

So the voltage on your dry contacts will be whatever you have wired up to it. If the lighting control is 0-10V, then you will see 0V on one contact and 10V on the other when open, and both contacts will read either 0V or 10V (depending on how you wire it on the lighting side) when the contactor is closed.

A dry contact set is the equivalent of a snap switch. It can be SPST, SPDT or some variation on that.

When the alarm is energized, you want both contactors to pull in. That means that one side of each coil will be +24V and the other side of each coil will be 0V. How you get the alarm to do that depends on what outputs you have from the alarm.

 

[templdl]

When my fire alarm is energized, I have two contractors that need to be energized. I have 2 sets of relays both with a set of dry contacts. One contactor is suposed to turn on some lights and the other is to shut off some plugs. I have the dry contacts for the lights wired as normally open, so when energized the contactor should pull in. I have the other set of contacts wired as normally closed so when energized the contactor should release.

My coil on my contactor is 24v

When the alarm is energized should I have 24v on both sets of dry contacts?

Should my coil on my contactor be 24v?

The is who I has interpreted you post:
The key point is that you have 2 sets of relays with dry contacts. What you need is a 24v power supply, I'm assuming 24v AC, with sufficient va to power the coils.
When de-energized the "dry contacts" would be open. By providing 24v to one side of the contacts then to one side of the contactor coil and the returning to the 24v power supply. The relay when energized closes the contacts an energized the contactor's.
The dry contacts of the relay should be rated 10a ac which should be sufficient. You should add a suitably sized fuse between the relay and contactor and recommend that the line between the power supply and contactor be grounded.
The contactor contacts are to be configured and connected as my be required.
Please not that the contactor coils can be 120vac an then use a commonly available 120v lighting circuit for supply power and eliminate the been for the 24v supply.

 

[GoldDigger]

Please not that the contactor coils can be 120vac an then use a commonly available 120v lighting circuit for supply power and eliminate the been for the 24v supply.

Provided that the relay dry contacts are rated for 120V AC and the wiring used is Class 1 (if fused) or article 300.

 

[goldstar]

Why are you using the 24 VDC supply from the FACP to energize your relays ? If you had a situation where you needed to operate something that required 24 VDC (i.e door strikes, flashing lights, bed shakers, etc.) in a utility power fail condition it would make sense. Bear in mind, in a power fail condition those relays are still going to pull in on battery standby and, in all probability, have an adverse affect on the NFPA requirements of standby requirement time. Obviously, you're not going to power the lights in a power fail condition. Personally speaking, I would use the dry alarm contact of the FACP to energize a 120 VAC relay (or relays) to accomplish your task.

 

[mgookin]

When my fire alarm is energized, I have two contractors that need to be energized. I have 2 sets of relays both with a set of dry contacts. One contactor is suposed to turn on some lights and the other is to shut off some plugs. I have the dry contacts for the lights wired as normally open, so when energized the contactor should pull in. I have the other set of contacts wired as normally closed so when energized the contactor should release.

My coil on my contactor is 24v

When the alarm is energized should I have 24v on both sets of dry contacts?

Should my coil on my contactor be 24v?

First question: On the control side of the relay you'll have +24V on one pin and -24V on the other (24VDC, right?). The load side will be whatever the load is and whether you're on the NO or NC relay.

Second question: Yes, if that's what the FACP provides to power a control circuit.

I wouldn't worry about your standby time. Easy calculation is mAh of the batteries and the draw. A 24VDC relay coil consumes very little power - it will be in the relay specs.

 

[gadfly56]

When my fire alarm is energized, I have two contractors that need to be energized. I have 2 sets of relays both with a set of dry contacts. One contactor is suposed to turn on some lights and the other is to shut off some plugs. I have the dry contacts for the lights wired as normally open, so when energized the contactor should pull in. I have the other set of contacts wired as normally closed so when energized the contactor should release.

My coil on my contactor is 24v

When the alarm is energized should I have 24v on both sets of dry contacts?

Should my coil on my contactor be 24v?

I'm going to guess that you're dealing with a nightclub or something very similar. When the fire alarm is activated, you need to kill the sound (plugs) and bring up the house lights. You should consider, how do I do this in a fail-safe fashion? What could go wrong that keeps the sound on and the lights off? The thing that should then spring to mind is not that you should energize the contactors to operate, but that you should DE-energize them to the desired state.

The relay module on your addressable fire alarm control panel (you can't easily use a conventional panel for this) will be a form "C" type. This means it can be wired NO/NC. You can usually use the 24 VDC auxilliary power on the FACP to power the coils on the contactors, the draw is usually low enough. When the contactors are pulled in, it completes the supply for the plugs (might be a separate subpanel) and turns off the lighting bypass. When the fire alarm is activated, the relays turn OFF the power to the coils and it's sound off and lights on. Note that if someone took an ax to the FACP it would go to the fail-safe condition of sound off, house lights on. This is the way to go.