shunt trip

[George Stolz]

The really sensitive issue is that smoke recall will bring the car down to the primary recall floor (usually) and open the doors. Then the fire fighters arrive, put their key in and use the car to stage men and equipment wherever their action plan calls for. Since their key overrides the elevator safety sequence, there is usually no way to do a second recall in the event the heat detector goes off. There is a potential for responders to be inside the car when the power dies. And if there's already enough heat to trip the sprinkler, here's hoping it keeps the fire at bay long enough to evac the responders. There needs to be more discussion on this issue between the fire alarm folks and the elevator folks, with the fire service thrown in for good measure.

It's not my job to train firemen that the little hat means you take your life in your own hands by using the elevator. They are more skilled in their job than I could pretend to be, I have faith in them.

 

[ADub]

No its shut down by LPS disconnect but its not a shunt trip button it only operates by a breaker controlled by heat detectors in shaft or elevator machine room I think we got off to elevators I was interested in the shunt trip button on main service which has nothing to do with elevators at all .

It doesn't matter what the end switch is, it's still a shunt.


Sent from my iPhone using Tapatalk

 

[Ingenieur]

The really sensitive issue is that smoke recall will bring the car down to the primary recall floor (usually) and open the doors. Then the fire fighters arrive, put their key in and use the car to stage men and equipment wherever their action plan calls for. Since their key overrides the elevator safety sequence, there is usually no way to do a second recall in the event the heat detector goes off. There is a potential for responders to be inside the car when the power dies. And if there's already enough heat to trip the sprinkler, here's hoping it keeps the fire at bay long enough to evac the responders. There needs to be more discussion on this issue between the fire alarm folks and the elevator folks, with the fire service thrown in for good measure.

Pretty sure their key manually overrides everything
even the shunt trip
if it has already tripped they can override and reset
they can actually go to a landing where the detectors have tripped
usually there is a fire fighters elevator control station, fire alarm system and phone/intercom/comm in close proximity for coordination

I'll pull my code and look on Monday

I know this is a complicated issue
But for every scenario you find an advantage you can find the opposite
human judgement during operation is critical
just because you CAN do something doesn't mean you should
you have to give the firemen all options and trust them to use them wisely

 

[GrayHair]

Since the firefighter's switch is part of the elevator controls, I see it having no effect when those controls have no power.

Hoistway and/or machine room smoke detectors on systems I designed always included a 135° heat detector. Funny how that happened. My personal preference was to have the sprinkler company install a suppression panel and let them do the required power removal.

 

[Ingenieur]

Since the firefighter's switch is part of the elevator controls, I see it having no effect when those controls have no power.

Hoistway and/or machine room smoke detectors on systems I designed always included a 135° heat detector. Funny how that happened. My personal preference was to have the sprinkler company install a suppression panel and let them do the required power removal.

If it hasn't tripped they can override it
basically bypass fire alarm interlocks
if it has they can override and reset
then they have control

the thermal shunt trip is allowed to have a time delay long enough to get the car to a safe landing

a flow switch can be used to shunt trip but no td is allowed

only the elevator in the affected shaft is shut down
the others go thru the fire emergency procedure

 

[iwire]

I have wired, tested and even disconnected quite a few and not one of them could be bypassed. If the heat trips the shunt activates.

 

[Ingenieur]

I have wired, tested and even disconnected quite a few and not one of them could be bypassed. If the heat trips the shunt activates.

Obviously

but a detector can be overridden and the shunt reset manually easy with addressable systems
as far as I know there is no requirement for a hardwired system
only fail safe
alarm upon a loss of shunt trip power

many elevators have centralized controls
some bldgs may have many elevators
shutting all control power off for a single shaft thermal would render ALL inoperable
that is not how it works

even some ckts of the associated shaft remain on
lighting
comm
pit power
room ltg hvac etc

I think the intent is to remove driving machine power (which spring sets the brake)
not sure if control power has to be removed (main line power)

I'll ask for clarification
I am a member of the ASME A17 Committee

 

[ohmhead]

Obviously

but a detector can be overridden and the shunt reset manually easy with addressable systems
as far as I know there is no requirement for a hardwired system
only fail safe
alarm upon a loss of shunt trip power

many elevators have centralized controls
some bldgs may have many elevators
shutting all control power off for a single shaft thermal would render ALL inoperable
that is not how it works

even some ckts of the associated shaft remain on
lighting
comm
pit power
room ltg hvac etc

I think the intent is to remove driving machine power (which spring sets the brake)
not sure if control power has to be removed (main line power)

I'll ask for clarification
I am a member of the ASME A17 Committee

This is how the shunt trip breaker inside the power module works if the elevator heat detector goes off in pit or top of shaft or machine room the elevator shunts . No power to elevator period it comes down to the first floor stops . Not even the fire dept can operate elevator with keys they have .

If the elevator company like Otis elevator resets the shunted breaker in power module it will operate. Power module is inside the elevator machine room it has fire alarm controls and elevator power disconnect inside in one package .
They don't use breakers anymore in remote panels to shunt elevators. No one remotely can reset breaker to a tripped elevator only the person whos in charge at that time fire dept wont reset its off. As to the shunt trip there always on the outside of building at 7 foot up from finish grade. Or they are in security room which is secure no one goes in that room but security. Its for safety in case of a fire in the building if someone trips it that's tuff luck but I never heard of anyone ever doing it. I think most people would not know what to do or what it was for.

When we do a stadium there is lots of emergency power so lights will be coming back on in 10 seconds or less. The design today is different then years ago.

 

[Ingenieur]

This is how the shunt trip breaker inside the power module works if the elevator heat detector goes off in pit or top of shaft or machine room the elevator shunts . No power to elevator period it comes down to the first floor stops . Not even the fire dept can operate elevator with keys they have .

If the elevator company like Otis elevator resets the shunted breaker in power module it will operate. Power module is inside the elevator machine room it has fire alarm controls and elevator power disconnect inside in one package .
They don't use breakers anymore in remote panels to shunt elevators. No one remotely can reset breaker to a tripped elevator only the person whos in charge at that time fire dept wont reset its off. As to the shunt trip there always on the outside of building at 7 foot up from finish grade. Or they are in security room which is secure no one goes in that room but security. Its for safety in case of a fire in the building if someone trips it that's tuff luck but I never heard of anyone ever doing it. I think most people would not know what to do or what it was for.

When we do a stadium there is lots of emergency power so lights will be coming back on in 10 seconds or less. The design today is different then years ago.

if shunt trip immediately removes power how can the elevator travel?
there is a time delay
there usually is a door switch that will bypass the td
so if the elevator arrives at a landing before the td expires the door switch will hit the shunt (or whatever device they use, like you said a combo disconnect/shunt now a days, eaton and littelfuse make one, usually fused) http://m.littelfuse.com/products/fu...ps-shunt-trip-elevator-disconnect-switch.aspx

The key won't override until it is reset in the elevator control room
can't be done remotely
has to be done by 'qualified personnel' as defined in the code

all other controls remain operational, epd's
over travel
door switches
governor switch
etc

 

[George Stolz]

but a detector can be overridden and the shunt reset manually easy with addressable systems
as far as I know there is no requirement for a hardwired system
only fail safe
alarm upon a loss of shunt trip power

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.

 

[iwire]

Obviously

but a detector can be overridden and the shunt reset manually easy with addressable systems
as far as I know there is no requirement for a hardwired system
only fail safe
alarm upon a loss of shunt trip power

many elevators have centralized controls
some bldgs may have many elevators
shutting all control power off for a single shaft thermal would render ALL inoperable
that is not how it works

even some ckts of the associated shaft remain on
lighting
comm
pit power
room ltg hvac etc

I think the intent is to remove driving machine power (which spring sets the brake)
not sure if control power has to be removed (main line power)

I'll ask for clarification
I am a member of the ASME A17 Committee

I have no idea how it is done where you are but here there are no bypasses

If the heat triggers the shunt trips and the elevator stops. End of story.


In RI about 2005 we were going around disconnecting the power to the shunt circuits per order of the RI elevator inspection department.

 

[Sahib]

if shunt trip immediately removes power how can the elevator travel?

With stored energy mechanism to the nearest stop.

 

[George Stolz]

With stored energy mechanism to the nearest stop.

Which, depending on the weight of the occupants could be up or down if between floors - which should not happen in the event of a elevator-related fire alarm because the batteries get opened as well; the car should be parked on a recall floor with doors locked open, fire hat on. If someone hops on with a fire key they have a sincere chance of getting trapped between floors in the car.

 

[George Stolz]

You know, in my area elevator guys (inspectors and installers alike) are about the worst for quoting code without opening one, and requiring one thing on one job and forbidding it on the next. It's kind of comforting to see that this is a nationwide problem. And kinda scary.

 

[George Stolz]

In RI about 2005 we were going around disconnecting the power to the shunt circuits per order of the RI elevator inspection department.

Why?

 

[gadfly56]

if shunt trip immediately removes power how can the elevator travel?
there is a time delay
there usually is a door switch that will bypass the td
so if the elevator arrives at a landing before the td expires the door switch will hit the shunt (or whatever device they use, like you said a combo disconnect/shunt now a days, eaton and littelfuse make one, usually fused) http://m.littelfuse.com/products/fu...ps-shunt-trip-elevator-disconnect-switch.aspx

The key won't override until it is reset in the elevator control room
can't be done remotely
has to be done by 'qualified personnel' as defined in the code

all other controls remain operational, epd's
over travel
door switches
governor switch
etc

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.

 

[dkidd]

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.

You're right, no time delay on the heat detector activating the shunt trip. The delay is on the initial alarm and recall to allow for travel. The power to the battery charger is disconnected, but it can be used to activate the lowering solenoid.

 

[gadfly56]

You're right, no time delay on the heat detector activating the shunt trip. The delay is on the initial alarm and recall to allow for travel. The power to the battery charger is disconnected, but it can be used to activate the lowering solenoid.

The problem is that you are going to get smoke in the shaft long before you have enough heat to activate the sprinkler. The car will already be in emergency service. Once the firefighter's key overrides the elevator recall there's no mechanism to a) let them know there might be a pending power shutdown b) seize control of the elevator back from the firefighters and force the car to a recall floor and then terminate power. And by the way, the shunt trip sequence is the same if the heat detector in the elevator machine room goes off.

 

[Ingenieur]

With stored energy mechanism to the nearest stop.

????
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

 

[Ingenieur]

You're right, no time delay on the heat detector activating the shunt trip. The delay is on the initial alarm and recall to allow for travel. The power to the battery charger is disconnected, but it can be used to activate the lowering solenoid.

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

only on heat detectors
no delay on flow switches