shunt trip

[Ingenieur]

No, there is no time delay. The elevator stops dead where it is unless there is some purely mechanical means to bring it to a landing. The emergency battery back up is disconnected by the same shunt sequence. You can't override the shunt once it trips, someone has to manually reset the breaker, and if the heat detector is still in alarm it's going to trip again unless you're removing power to the trip coil as well.

Page 106
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[Ingenieur]

No, actually you cannot change programming during a fire alarm, that too is a fail safe.

If a smoke detector in the pit or in the shaft triggers the alarm initiating recall, your only time delay to the shunt is the amount of time it takes for the heat detector to trigger. There is no override or bypass, short of killing power to the shunt circuit to eliminate the power to the shunt when the fire alarm closes the relay.

The fire fighters key switch goes to an addressable input module
he can bypass smoke detectors and travel to a floor in alarm
the floor exactly where he is needed

as far as the shaft heat detector
it has a time delay to allow the car to get to a landing
as soon as the doors open the td is bypased and shunt trip occurs
page 106
http://www.afaa.org/Webinars/AFAA Webinar - 1-27-2012 - FA & Elevators.pdf


the shunt trip can't be bypassed or inhibited prior to operation
other than the td to landing
well it easily could be with an addressable relay but it's not allowed to be
the shunt trigger ie heat detector can be bypassed after it has tripped and been manually reset

 

[iwire]

The fire fighters key switch goes to an addressable input module
he can bypass smoke detectors and travel to a floor in alarm
the floor exactly where he is needed

Not here, the fire fighters key ties into the elevator control system.

We do not have any inputs from the elevator control system to the FACP, we have outputs from the FACP to the elevator control system.

as far as the shaft heat detector
it has a time delay to allow the car to get to a landing
as soon as the doors open the td is bypased and shunt trip occurs

Again, not the case here. It is often a non-addressable heat detector controlling the shunt trip directly. If the heat detector activates the shunt is activated immediately.

The only 'time delay' is the activation of a smoke detector which parks the car on the primary or alternate floor. At that point the firefighters can use their key to overide but they would be subject to entrapment if the shunt is activated.

 

[iwire]

Why?

So firefighters would not become trapped due to the very thing we are discussing.

 

[gadfly56]

Page 106
http://www.afaa.org/Webinars/AFAA Webinar - 1-27-2012 - FA & Elevators.pdf

only on heat detectors
no delay on flow switches

That's a great presentation, but the fact is it doesn't deal with the fire service overriding the elevator recall function. The sequence as presented is 1.) smoke detection > 2.) car to recall floor, doors open > 3.) continued heat buildup > 4.) heat detector activation > 5.) car to recall floor (but it's already there) > 6.) power off (after delay) > 7.) sprinkler activated. The fire fighters come in somewhere between 2.) and 4.) and bypass all recall functions with their key. It can be solved, but no one seems to be pursuing it right now.

 

[Ingenieur]

Not here, the fire fighters key ties into the elevator control system.

We do not have any inputs from the elevator control system to the FACP, we have outputs from the FACP to the elevator control system.

Again, not the case here. It is often a non-addressable heat detector controlling the shunt trip directly. If the heat detector activates the shunt is activated immediately.

The only 'time delay' is the activation of a smoke detector which parks the car on the primary or alternate floor. At that point the firefighters can use their key to overide but they would be subject to entrapment if the shunt is activated.

so does the fire alarm system
the key switch bypasses the fa contacts in the elev control system so they can manually control the car

Those are national codes

the shunt td was introduced to prevent trapping people in the car in a shaft with hot temps acting as a flue
the rationale is since it is set lower than the sprinkler head there is an intrinsic time delay between heat and sprinkler
since the danger is the water why not take advantage of this inherent delay to get the passengers out of the potentially dangerous situatiion before the water is introduced

it is allowed and makes no sense not to do it
no increase in risk and actually removes risk, ie, passengers in a hot shaft
the resson they can override the shunt and reset it
to get people out of a hot shaft

 

[Ingenieur]

That's a great presentation, but the fact is it doesn't deal with the fire service overriding the elevator recall function. The sequence as presented is 1.) smoke detection > 2.) car to recall floor, doors open > 3.) continued heat buildup > 4.) heat detector activation > 5.) car to recall floor (but it's already there) > 6.) power off (after delay) > 7.) sprinkler activated. The fire fighters come in somewhere between 2.) and 4.) and bypass all recall functions with their key. It can be solved, but no one seems to be pursuing it right now.

The shunt td is taking advantage of the inherent td between heat detector and sprinkler activation to get people out of the car before first responders arrive
they use the door switch to make sure once it is parked the shunt goes and the car can't be used automatically until steps are taken

 

[George Stolz]

so does the fire alarm system
the key switch bypasses the fa contacts in the elev control system so they can manually control the car

Those are national codes

Not to sound impatient, but sifting through a 150-page presentation instead of simply quoting the relevant code to support your as yet unsubstantiated opinion is not very convincing. I have wired many elevators, have had numerous discussions with fire officials regarding precisely how the elevators I power and connect fire alarm to behave, and this is the first I've ever heard about introducing a couple more FA relays to override its own recalls in the event of a fire. For that matter some elevators aren't even compatible with multiple recall signals, it's generally one and done awaiting shunt. Second recalls are either ignored or required to be squelched by the FACP to prevent malfunction of the elevator.

Respectfully, how many elevators have you actually connected to fire alarm systems, or are you just a designer? Is there a possibility that the installers have been silently ignoring your specs because they are physically impossible to execute?

the shunt td was introduced to prevent trapping people in the car in a shaft with hot temps acting as a flue
the rationale is since it is set lower than the sprinkler head there is an intrinsic time delay between heat and sprinkler
since the danger is the water why not take advantage of this inherent delay to get the passengers out of the potentially dangerous situatiion before the water is introduced

I echo iwire's statements from above; the only time delay (intentional or otherwise) present in any fire alarm / elevator system I have dealt with is the intentional delay between smoke, heat and head. The only variation I have from the other posters is that we tend to use 190° heats that are spec'ed by our FA designers and this puts a burden on the sprinkler guy to choose the proper head. There are no additional controls or relays to delay anything.

it is allowed and makes no sense not to do it
no increase in risk and actually removes risk, ie, passengers in a hot shaft
the resson they can override the shunt and reset it
to get people out of a hot shaft

There is no risk to the passengers as it is, unless they refuse to get out of an elevator car full of smoke with an open door to use...? :blink:

 

[donaldelectrician]

Shunt Trip Elevator

Shunt Trip Elevator

ive seen EPO buttons on UPS and Xray but not on a elevator .

Had 3 Shunt Trips for elevators , fed 347 V TRANS , at each elevator VFD Loco , New Sky Boxes ,

Homestead Motor Speedway … 2005




Don

 

[George Stolz]

????
what is this device?
regen
dynamic
flywheel

all they do here is allow a time delay until a landing door opens then bypass the td and shunt

I believe Sahib was referring to the safeties that exist in case of a run-of-the-mill powerloss, which would often rely on gravity and and battery supply of the elevator controller CPU to allow the elevator to coast up or down and open the doors to allow people out during a regular powerloss. This system is generally required to be shunted along with everything else during a fire involving the elevator pit, shaft, or control room.

 

[iwire]

so does the fire alarm system
the key switch bypasses the fa contacts in the elev control system so they can manually control the car

The the key switch can only overide the inputs from the FACP

Here the heat detector that controls the shunt often has no connection at all to the fire panel.

Those are national codes

They may have national in the title but don't expect them to be used everywhere.

the shunt td was introduced to prevent trapping people in the car in a shaft with hot temps acting as a flue
the rationale is since it is set lower than the sprinkler head there is an intrinsic time delay between heat and sprinkler
since the danger is the water why not take advantage of this inherent delay to get the passengers out of the potentially dangerous situatiion before the water is introduced

it is allowed and makes no sense not to do it
no increase in risk and actually removes risk, ie, passengers in a hot shaft
the resson they can override the shunt and reset it
to get people out of a hot shaft

Awesome, yet still not the case here.

 

[Sahib]

Awesome, yet still not the case here.

Need improved safety features?

 

[iwire]

Need improved safety features?

I don't think you are in a position to judge. :happyno:

 

[Sahib]

That is nuts. I am just asking a question.

 

[ron]

So firefighters would not become trapped due to the very thing we are discussing.

No shunt trip of elevators in NYC either.

 

[Ingenieur]

No shunt trip of elevators in NYC either.

They don't shunt trip main line power (with or without a td) if a heat det goes off in the associated sprinklered shaft?

 

[ron]

They don't shunt trip main line power (with or without a td) if a heat det goes off in the associated sprinklered shaft?

Correct. No heat detector either, just a smoke for recall

 

[Ingenieur]

Correct. No heat detector either, just a smoke for recall

what if the smoke doesn't go off and the sprinkler does
unlikely but has happened due heat build up at the top of the shaft
does the sprinkler stop or recall the elevator?

 

[gadfly56]

what if the smoke doesn't go off and the sprinkler does
unlikely but has happened due heat build up at the top of the shaft
does the sprinkler stop or recall the elevator?

You get to explore the intricacies of the electricity/water interface up close and personal.

 

[Ingenieur]

You get to explore the intricacies of the electricity/water interface up close and personal.

Sounds like fun