Elevator Shunt Trip

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roger

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Staff member
Location
Fl
Occupation
Retired Electrician
Re: Elevator Shunt Trip

Nick, I don't know.(go back to my first and second paragraphs) :D I asked this question awhile back and was told this was the way it was.

This made more sense to me. I would rather be wet than burnt.

I will ask our technology devision on Monday, I probably heard it the way I wanted it to sound.

Roger
 

iwire

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Staff member
Location
Massachusetts
Re: Elevator Shunt Trip

Questions like this is why I say get the engineer to do his job, simply putting something on the print is not engineering as I know it.

In the jobs I work on asking for clarification on something like this would not cost me a dime, and as to delay that would be the EEs problem, unless I had waited till the last minute then I would be in a bad spot for delays.
 

ron

Senior Member
Re: Elevator Shunt Trip

ANSI 17.1 does not identify the temp level of the heat detector to activate the shunt trip. Generally the heat detector is a standard 135 degree and the sprinkler head is at 165 degree.
The power needs to be removed from the elevator prior to application of water.
You could also activate the shunt trip with a water flow switch positioned to monitor water flow at the elevator shaft.
 

Nick

Senior Member
Re: Elevator Shunt Trip

If you used a water flow switch to activate the shunt trip, you would be shunting the power a split second after the application of water. So now what about elevator recall? Is it the intent of the various codes on this subject that the occupants remain stuck between floors with water pouring down on them until emergency help can arrive? :confused:
 

ron

Senior Member
Re: Elevator Shunt Trip

Shunt trip is a seperate function from recall. Recall is activated by smoke detectors, where shunt trip is activated by heat detectors or water flow (designers choice).
Generally, smoke detection will occur well in advance of 135 degree temperatures to activate shunt trip, or 165 degree to activate water flow/shunt trip.
 

hornetd

Senior Member
Location
Maryland
Re: Elevator Shunt Trip

In addition to being an electrician I am a firefighter rescuer. The installation of shunt trips that are not integrated with the recall sequence turns the elevator into coffins on strings or coffins on tubes. The smoke detectors in the shaft, lobby, and machine room cause the elevators to return to their primary or alternate floor, firefighters arrive and initiate fireman's service, an entire company of firefighters is in the elevator when the shunt trip deprives the elevator of all power and it stops dead between floors or even in the blind portion of the shaft. The elevator code needs to be changed to require that the heat detectors cause recall from fireman's service and the water in the sprinklers would be controlled by a pre action valve. The pre action valve would only open after recall was complete. Yes I do know that that would cost more money. So tell me how much are the lives of an entire fire company worth?
--
Tom
 

hornetd

Senior Member
Location
Maryland
Re: Elevator Shunt Trip

Originally posted by don_resqcapt19:
Is this system really designed in a manner that will guarantee that the elevator car becomes a "people oven" if the elevator recall is not completed prior to the activation of the heat detector, or am I missing something????
Don
Don
I have gone through elevator inspections were the inspector tested the heat detector function with a lighter. It took me fifteen minutes to restore power to the elevator and get those dumb SOBs down. I told them that those fixed temperature heat detectors are one time use only and they replied that they had to test it anyway. We finally filed a written misconduct complaint in oder to get the practice stopped.

Shunt trips are what I call elevator inspectors revenge. We wouldn't keep our sprinklers out of their shafts so they booby trap the elevators so that we may have to hike the stairs to avoid becoming trapped.
--
Tom

[ March 22, 2003, 10:37 AM: Message edited by: hornetd ]
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: Elevator Shunt Trip

Lately the hydraulic elevators here in MA have been coming with a small battery back up that in the case of power failure opens the valve and brings the car to the primary floor then opens the door.

How or if this is integrated into recall I do not know, hopefully if the recall has called the car to the alternate floor it will stay there even with a power failure, but in general at least this gets people out of the car on a utility failure.

[ March 22, 2003, 03:52 PM: Message edited by: iwire ]
 

hornetd

Senior Member
Location
Maryland
Re: Elevator Shunt Trip

Originally posted by iwire:
Lately the hydraulic elevators here in MA have been coming with a small battery back up that in the case of power failure opens the valve and brings the car to the primary floor then opens the door.

How or if this is integrated into recall I do not know, hopefully if the recall has called the car to the alternate floor it will stay there even with a power failure, but in general at least this gets people out of the car on a utility failure.
Well at least that makes it less likely that people will suffocate or burn alive.
 
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