[Aegis]

So I have a 200kw 3 phase generator on a roof of a 10 story building. In its control box it has two sets of wires. Yellow/Grey is the generator trouble signal, black and red are the generator running signal (photo). These wires go all the way down to the alarm panel so that it's displayed on the main floor (photo) what's happening on the roof.

Im installing an actuator for the vent of the generator (photo), also an alarm panel right next to it (photo). This alarm panel on the roof sets off an alarm if the vent doesn't open when the generator starts. This panel has an alarm dry contact.

My question is, can I connect this dry contact of this new panel to the grey and yellow in the generator control box? Can I connect two dry contacts together that then go down to the security panel?

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[Aegis]

Depends whether they are NO or NC and isolated, plus be careful of the terminating resistor. Would it be better to run another pair down and have the panel programmed for another input?

Yes I could run seperate wires down there I'm even thinking of doing that way. I believe they're both normally open and isolated but I'll check. I know for sure the dry contact in the panel I'm installing is normally open.

So just so I'm understanding clearly, if there's ever a problem in the generator on the roof, the relay changes state and the normally open dry contacts close causing the signal coming from the main floor security panel to get its signal.

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[Aegis]

Yes.

Connect in parallel so either one triggers an alarm.

Ok thank you, would the resistor in between the gray and yellow terminals in the first photo screw this up?

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[Aegis]

I'd want the separate wires because then it can be a separate message to the system, I'd much rather have two lights for two faults than one light that narrows it down to two faults.

But I don't like to touch these things, and if I do, I want clear written communications with the person responsible for that alarm, so that I don't screw them up, or get blamed for screwing them up.

Yeah that makes sense. There's a spare set of wires in the Gen control box, I just have to see if they go back to the main security panel. If they do then I may connect them and phone the company to come hook it up in their own monitoring panel.

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[Aegis]

This looks like as mention J1939 or EOL. With CAN/J1939 dry contacts won’t work other than the fact that it will appear as a “bus off” error causing comms to “fail” on every device connected to it. If it’s only the generator this may not be a bad thing. All serial protocols (Modbus, CAN, LON) are jammed by a dead short.

It could be EOL. In this case the alarm panel is looking for a certain resistance (voltage drop). A “short” indicates alarm. An open indicates broken wire. This is a common fire alarm wiring scheme with smoke detectors but I haven’t seen it in gensets.

I highly doubt it is using NC contacts like an E-Stop because of the resistor.

I pulled the grey and yellow wires off the terminals and checked the screws and it was NO. I put my dry contact alarm signal on the grey and yellow and everything worked. When the actuator is in trouble mode, the main panel on the ground floor has an alert

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[Aegis]

I was about to post that the annunciator looks a lot like a fire alarm panel; upper LED red for alarm, lower LED yellow for trouble. And like any modern fire alarm system, it will use a supervised Normally Open input. The thing to watch out for is the normal state of the output relay on damper panel; is the relay active when normal, or is it active only when in alarm?

When the actuator panel is in its normal state of open/closed damper the alert dry contact is still open, I checked it. It only closes if the actuator takes longer than 30 seconds to open the vent or if I hit the test button on the front of the panel. So it's only active when in alert mode.

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[Aegis]

Un related question.

The vent lovers installed. Is this for a heat reclaim system or just to maintain a good motor/cabinet air temperature in the winter time?

The generator is in an enclosed housing on the roof. When the generator turns on it needs ventilation. The Gen signal tells my panel that it's running and the panel tells the actuator to open the vent. If the actuator takes longer than 30 seconds to open an alarm goes off - the trouble signal.

I believe this is a new gas code in Ontario. Or at least the TSSA/generator inspector keeps making me put these in.
These lovers are powered closed as well so if there's a loss of power it'll open.

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