What relay is connected to the elevator depends on what is being done.
The smoke detectors and heat detectors use the fire alarm control panel:
- Because "Where there's smoke, there's fire", guides the elevator to a smokeless floor
- Because soon it might stop between floors, warns the firefighters to get out of the elevator car
- Because heat indicates fire, stops the movement of the elevator (shunt the power)
The relays are:
The Egress Floor (Primary Floor) Elevator Lobby Smoke Detector Relay - it sends the elevator to the alternate floor - The addressable fire alarm panel should be programmed so only the smoke detector in the primary floor elevator lobby will activate the egress floor relay.
If there's smoke detected in the egress floor, rather than letting passengers off on a floor where there's smoke, the elevator becomes "Captured", and goes to the alternate floor, letting let the passengers off.
All Other Elevator Lobby Smoke Detector Relay - The addressable fire alarm panel should be programmed so only the smoke detectors in the elevator lobbies, that are not on the egress floor, activate this relay. Sometimes the smoke detectors in the machine room and in the elevator shaft (if there's a detector there) are included.
If there's smoke detected in the Egress Floor, rather than letting passengers off on a floor where there's smoke, the elevator becomes "Captured", and goes to the primary egress floor to let the passengers off.
Firefighter's Hat Relay - The addressable fire alarm panel should be programmed so only the smoke detectors in the machine room and in the elevator shaft (if any) activate this relay.
The relay activates the red flashing "Firefighter's Hat" light inside the elevator car and on the call button panel on the egress floor. The purpose of the flashing light is to warn firefighters that smoke is in the machine room or elevator shaft, and the elevator may stop. A stopped elevator will trap anyone inside.
Shunt Relay - The addressable panel should be programmed so only the heat detectors in the elevator machine room or the elevator shaft activate this relay.
Should there be a fire in the machine room or the elevator shaft, this relay activates the "Shunt" circuit breaker for the elevator motor to stop the elevator dead in its tracks.
So the heat detectors detect heat before the sprinkler head gets too hot and activates, spraying water. Inside the machine room or the elevator shaft, the heat detectors are supposed to be mounted within 2 feet (0.6 meter) of any sprinkler heads.
Power Supervision for Shunt Relay
Supervision in a life-safety system doesn't fix anything; supervision in a life-safety system only calls to the owner's attention that something needs correction. In the case of the power for the shunt relay, a supervision sensor (end of line device) needs to be placed as close as possible to the switch (shunt relay) to call attention that the life-safety shunting-power has gone missing.
Under normal circumstances, as long as power gets to the shunt relay, the power can be sent on to the shunt circuit breaker when a life-safety shunting event occurs.
If the supervision sensor (end of line device), commonly a relay, fails to sense power at the shunt relay, the coil in the supervision-sensor-relay relaxes, sending a supervisory signal on to the "Elevator Shunt Power is Missing" addressable-input-module for the fire alarm system.
Fire Alarm Control Panel Relays
On the actual printed circuit boards, very few fire alarm control panels have this many programmable relays. For this reason, addressable control panels are required, and the relays are addressable control relays that are attached to the Signaling Line Circuit (SLC). This is the same SLC that has the smoke detectors and heat detectors.
Also, the relays for smoke capture are supposed to be mounted in boxes within 3 feet (1 meter) of the elevator control box in the machine room. This is to keep the wires for the elevator control panel as short as possible.
The relay for the elevator shunt is also supposed to be mounted within 3 feet of the shunt circuit breaker. This also keeps the control wires for the shunt very short.
Talk to the Elevator Installers
There are many variations to the installation. To find out, you need to talk to the elevator installers before mounting the relays, and before wiring them.
They will also let you know exactly what is needed as far as normally-open or normally-closed contacts. Each elevator manufacturer has a different requirement.
Also, the elevator inspector may have ideas of what should be done. The elevator installers will have received instructions from the inspector. Again, talk to the installers.
Pre-Test the Elevator Capture Before the Inspector Arrives
Pre-testing of the elevator capture is almost mandatory. It is never good to fail the elevator inspection because something isn't right.
Usually, so a pre-test is be performed and any problems can be corrected, a day or two before the elevator inspection, pre-test the installation with the elevator installers. If you wait until the day-of the elevator inspection, you need to be very confident you did the installation correctly, and the elevator installers also have to be very confident in your work.
Dry Contacts or 24 Volts
Dry power out of a relay, or dry contact from the relay is means no voltage, and no current emanates, or comes from the relay contacts. If you hold a relay in your hand, or hold a waterflow switch in your hand, and there are no wires attached to either the switch or the relay, the output contacts on the relay, and the contacts on the switch are dry contacts. Shorting two wires together is exactly the same as using (or closing) dry contacts.
Almost always, the elevator company needs dry contacts from the relays. You will have to work with the elevator installers to find out how the relay outputs are supposed to be programmed and wired.
Douglas Krantz
