elevator shunt trips
- Thread starter zak4574
- Start date
- Status
cadpoint
Senior Member
- Location
- Durham, NC
- Occupation
- Electrician - but not by NC Law.
Google (image) is your friend!
Top page searchs of Google images of " shunt trip " I used the third image from the left.
Here is an over view of most the the "Shunt"'s available. I beleive an elevator shunt is a dual element with remote shutdown. the remote is controled via a Fire alarm IE it breaks the voltage coil, or the sensing coil (F/A)
releases the current sensing coil...
The multi available shunts from one manufacture are shown here ( single line diagrams ) and there various descriptions Here
Welcome to the Live side of the MH forum!
Top page searchs of Google images of " shunt trip " I used the third image from the left.
Here is an over view of most the the "Shunt"'s available. I beleive an elevator shunt is a dual element with remote shutdown. the remote is controled via a Fire alarm IE it breaks the voltage coil, or the sensing coil (F/A)
releases the current sensing coil...
The multi available shunts from one manufacture are shown here ( single line diagrams ) and there various descriptions Here
Welcome to the Live side of the MH forum!
Last edited:
in the past 30 or 40 years elevators have incorporated devices intended to try to keep people from being cooked alive in the event of a fire. in a modern elevator, once a fa is in alarm, power is shut off (usually via a shunt trip mechanism) and the elevator is sent to a place where passengers can hopefully disembark safely, and only the fireman can use the elevator.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
I believe the shunt applies current to activate the coil. The weakness here is that if your current source is kaput, so is your shunt.
More typically, if one of the elevator lobby smoke detectors or the shaft smoke detector goes into alarm, the elevator car will return to the primary recall floor, unless the smoke detector in alarm is in the primary recall lobby, in which case the car is directed to the alternate recall floor.
Fire fighters can use the firefighters key to then overide the recall and operate the car.
The shunt trip is employed if the elevator shaft is sprinklered. In this case, a heat detector is mounted within 24" of the sprinkler and is selected to activate below the operating temperature of the sprinkler. When the heat detector is activated, the shunt cuts power to the elevator immediately, stopping the car wherever it is, potentially turning "New York's bravest", for example into "New York's crispiest". This is the way most codes are written. I have heard rumors of jurisdictions allowing immediate recall to the egress floor before the power drops out, but I haven't seen it myself.
kirkpatrick88
Member
- Location
- Denver, Colorado
Elevator shunt trip and firefighters
Elevator shunt trip and firefighters
Some additonal background information regarding the purpose of the shunt trip in elevator rooms.
The elevators are supposed to remain operational during a fire to allow the disabled to evacuate the building and the fire department to quickly reach the fire (Typically only used if the fire is above the 6th floor). The elevators will recall automatically when there is smoke detection in the elevator lobbies, elevator equipment room, and elevator shaft/hoistway. (Also known as phase 1 recall). This can also be done manually by the fire department using the override key at the control panel located in the lobby or fire control room. The fire department would then use their key to activate phase 2 (Emergency in car operation) to take manual control of the elevator.
If the smoke detector in the elevator equipment room activates, then the phase 1 indicator light (Usually fire helmet or maltese cross) in the elevator car will flash instead of turning on solid. This would tell the firefighters entering the elevator car that it is unsafe for firefighter use because of smoke in the elevator equipment room.
The theory of operation is that a fire extending into the elevator equipment room will first trigger a smoke detector that will initiate phase 1 recall and bring the elevator to the main (Primary) landing, open it's doors and be taken out of service. As the fire progresses, it activates the heat detector (Set at a temperature below the sprinkler head) which activates the shunt trip. As the heat increases, the fire sprinkler head would then activate and spray water on the now de-energized elevator equipment. This would remove the danger of water causing a malfunction in the elevator equipment that may prove to be unsafe for elevator car passengers and firefighters.
See ASME 17 for additional information.
Elevator shunt trip and firefighters
Some additonal background information regarding the purpose of the shunt trip in elevator rooms.
The elevators are supposed to remain operational during a fire to allow the disabled to evacuate the building and the fire department to quickly reach the fire (Typically only used if the fire is above the 6th floor). The elevators will recall automatically when there is smoke detection in the elevator lobbies, elevator equipment room, and elevator shaft/hoistway. (Also known as phase 1 recall). This can also be done manually by the fire department using the override key at the control panel located in the lobby or fire control room. The fire department would then use their key to activate phase 2 (Emergency in car operation) to take manual control of the elevator.
If the smoke detector in the elevator equipment room activates, then the phase 1 indicator light (Usually fire helmet or maltese cross) in the elevator car will flash instead of turning on solid. This would tell the firefighters entering the elevator car that it is unsafe for firefighter use because of smoke in the elevator equipment room.
The theory of operation is that a fire extending into the elevator equipment room will first trigger a smoke detector that will initiate phase 1 recall and bring the elevator to the main (Primary) landing, open it's doors and be taken out of service. As the fire progresses, it activates the heat detector (Set at a temperature below the sprinkler head) which activates the shunt trip. As the heat increases, the fire sprinkler head would then activate and spray water on the now de-energized elevator equipment. This would remove the danger of water causing a malfunction in the elevator equipment that may prove to be unsafe for elevator car passengers and firefighters.
See ASME 17 for additional information.
RJohnsonMasterElectrician
Senior Member
- Location
- Right now ??, previously VT
Shunt trip is used to turn off the power after the main disconnect to the elevator car and equipment room so energized equipment doesn't get wet.
At the same time the Heat detector at either bottom (if sprinkler head is above 2') or the top of shaft trips power is shunted and the FIRE HAT is lit up to warn the fire fighters who are responding to said emergency know that the fire has effected either the shaft or machine room and its not safe to use it.
I have heard talk about that sprinkler heads at the top of shafts are being phased out here where I have been working and hydralic units will be part of the past in the next decade or sooner.
At the same time the Heat detector at either bottom (if sprinkler head is above 2') or the top of shaft trips power is shunted and the FIRE HAT is lit up to warn the fire fighters who are responding to said emergency know that the fire has effected either the shaft or machine room and its not safe to use it.
I have heard talk about that sprinkler heads at the top of shafts are being phased out here where I have been working and hydralic units will be part of the past in the next decade or sooner.
someone should explain this to engineers...we are currently doing a walgreens (fun if you've never tried one)....the engineers spec'd a 125A 3PH GFCI for the elevator...shunt trip...GFCI....220.....221.....whatever it takes
Next time you are having a "chat" about the elevator there ~ use the word "escalator" instead.
It's fun to see how little people pay attention .....at least for some of us.:grin:
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