Fire Alarm & Elevators: Monitoring Shunt Trip

[George Stolz]

Why am I monitoring that there is shunt trip power available when I am getting that shunt power from a control transformer in the elevator disconnect? Whenever the elevator guy shuts down the disconnect (or the shunt trip does it's job) I get a supervisory alarm.

 

[iwire]

Why am I monitoring that there is shunt trip power available when I am getting that shunt power from a control transformer in the elevator disconnect? Whenever the elevator guy shuts down the disconnect (or the shunt trip does it's job) I get a supervisory alarm.

Is there a reason you can't put the control trans on the line side of the disconnect?

I have similar issue with RTUs that have self powered duct smokes, when the unit is serviced the duct smoke loses power putting a trouble in the system

 

[nhfire77]

Why am I monitoring that there is shunt trip power available when I am getting that shunt power from a control transformer in the elevator disconnect? Whenever the elevator guy shuts down the disconnect (or the shunt trip does it's job) I get a supervisory alarm.

Did that recently, the elevator guys told me something like this:

They want the loss of shunt trip capability to recognized, its life safety and everything critial has to me supervised.

If, some how the elevator has its normal power, but the power available to the shunt relay is lost, in the event of a fire in the machine room or hoistway, (heat detector alarm) the elevator would not shut down.

I guess they are monitoring the conductors that supply the shunt trip power, prior to the relay. I guess people have been disconnecting them?!?!?

 

[George Stolz]

Is there a reason you can't put the control trans on the line side of the disconnect?

Four reasons I'd hate to do that:

1. I'm the only one bothered by it to speak of - the owner will get a call once a day from last Thursday until tomorrow, big deal.

2. The manufacturers' one-line shows it being disconnected by the main, I'd hate to create confusion.

3. It would be easier to replace the transformer if it's disconnected locally.

4. It would mean I'd have power through the shunt trip indefinitely, instead of just long enough to do it's job, which leaves me more uneasy than the supervisory signal.

I just like to see the green light, makes me feel better about myself.

They want the loss of shunt trip capability to recognized, its life safety and everything critial has to me supervised.

If, some how the elevator has its normal power, but the power available to the shunt relay is lost, in the event of a fire in the machine room or hoistway, (heat detector alarm) the elevator would not shut down.

That begs another question: does your heat in the shaft activate the shunt? We have it to recall away from the detector, which makes more sense to me. Shunting on the shaft detector would essentially be locking passengers in with the fire.

Our programmer had it that way, it was changed to alternate recall on heat in the shaft.

 

[dkidd]

That begs another question: does your heat in the shaft activate the shunt? We have it to recall away from the detector, which makes more sense to me. Shunting on the shaft detector would essentially be locking passengers in with the fire.

The way the AHJs we work with want it is that the heat activates a timer that allows the elevator to reach the required floor before tripping.

An supervision is usually through the fire alarm panel.

 

[nhfire77]

That begs another question: does your heat in the shaft activate the shunt? We have it to recall away from the detector, which makes more sense to me. Shunting on the shaft detector would essentially be locking passengers in with the fire.

Our programmer had it that way, it was changed to alternate recall on heat in the shaft.

Oh you disagree with the idea of being trapped in a metal box with a fire below you???????

Yea, its in ANSI A17 I believe.

What first is supposed to happen is the smoke at the top of the shaft, performs a recall to the main floor and you cannot move the elevator, unless you place it in phase II operation (firefighter key control).

Then If the heat trips the panel, the panel trips a relay to activate the shunt.

The theory is, the heat detector trip temp(135F) is lower than the sprinkler head (165F) The sprinkler head and heat have to be within 2' of each other in the pit. So the heat will trip the shunt, kill the power, so when (if) the sprinkler head pops it will put out the fire and you wont mix water and electricity.

Realistically speaking the sprinkler head at the top of the shaft will go first, and you are getting wet anyway.



I agree with the delay timer option, but that's not how everyone does it. In MA, nothing in the pit (they have changed their minds about that, 5 years ago we had to pull out every smoke in every elevator pit, in a few more years we'll probably put them back)

In NH a heat is required, when sprinklered.

 

[LarryFine]

I don't know if it's compliant, but it seems a simple shunt-trip circuit monitor would be a low-current bulb across the tripping contacts, i.e., in series with the coil. The light would show presence of power and an intact trip coil, but have a low-enough current to not energize the shunt. Similar to an illuminated door chime button.

 

[iwire]

That begs another question: does your heat in the shaft activate the shunt? We have it to recall away from the detector, which makes more sense to me. Shunting on the shaft detector would essentially be locking passengers in with the fire.

Our programmer had it that way, it was changed to alternate recall on heat in the shaft.

Who approved the change?

I hope that was not a field decision.

 

[nhfire77]

I don't know if it's compliant, but it seems a simple shunt-trip circuit monitor would be a low-current bulb across the tripping contacts, i.e., in series with the coil. The light would show presence of power and an intact trip coil, but have a low-enough current to not energize the shunt. Similar to an illuminated door chime button.

Yes, but who's watching it? The theory is the fire alarm is supervised. Now if the lamp was in a constantly attended location that would make sense, but that's not normally available in most buildings.

Again, it is a bit of over kill I agree, but 2007 72.6.14.4.4 tells us "loss of voltage to the control circuit for the disconnecting means shall cause a supervisory signal..."

So I guess that is the ultimate answer.

 

[nhfire77]

Who approved the change?

I hope that was not a field decision.

Field decisions are awesome!! I love fixing those i$$ues during tests and inspections!

 

[LarryFine]

Again, it is a bit of over kill I agree, but 2007 72.6.14.4.4 tells us "loss of voltage to the control circuit for the disconnecting means shall cause a supervisory signal..."

Okay, how about a low-current NC relay held open by the closed current?

 

[iwire]

Okay, how about a low-current NC relay held open by the closed current?

Pretty much anything you use for fire alarm systems has to be listed for the purpose.

What George has now is working as it should it just bothers him.

When the disco is opened the shunt trip power is removed and the FACP goes into supervisory. It is doing what it is supposed to do.

 

[roger]

Okay, how about a low-current NC relay held open by the closed current?

I agree with Bob's post above and would add that most elevator inspection agencies won't go with anything that is not listed as part of an assembly which is why Bussman power modules are the way to go.

The question I have (I have an elevator in the works with the same requirement) is why the need to monitor it if the shunt trip feed is from the elevator breaker itself?

Has anyone been required to have the 30 sec delay for the shunt operation yet?

Roger

 

[iwire]

The question I have (I have an elevator in the works with the same requirement) is why the need to monitor it if the shunt trip feed is from the elevator breaker itself?

My WAG is that the code has no provision for commonsense.

Has anyone been required to have the 30 sec delay for the shunt operation yet?

No, have not heard of that.

 

[roger]

My WAG is that the code has no provision for commonsense.

DOH, I knew that.

No, have not heard of that.

Yeah, this job is the first I've heard of it too. The Engineer has told me that the NC DOL is requiring it but he didn't know if it was just NC or if was covered in ANSI 17.1.

Roger

 

[LarryFine]

Has anyone been required to have the 30 sec delay for the shunt operation yet?

No, but give me half a minute.

 

[George Stolz]

Who approved the change?

I hope that was not a field decision.

It was - the Fire Inspector was already impatient with inspecting a building that wasn't ready (we were, GC wasn't). I wasn't about to argue something with him that seemed sensible at the time, and already had been noted by the elevator guy and the foreman who'd been nailed for it before.

Again, it is a bit of over kill I agree, but 2007 72.6.14.4.4 tells us "loss of voltage to the control circuit for the disconnecting means shall cause a supervisory signal..."

So I guess that is the ultimate answer.

Ah ha! Thanks!

Has anyone been required to have the 30 sec delay for the shunt operation yet?

Here, it's assumed the smoke in the control room would go first, sending the elevator into alternate recall and locking the doors open on the second floor. Then, after the marshmellows are done, the heat would trigger and activate the shunt module.

I think I've seen a delayed shunt, but for the life of me I can't remember how it was set up.

 

[dkidd]

You might want to look at

http://forums.mikeholt.com/showthread.php/111882-elevator-shunt-trips?p=1026288

and

http://forums.mikeholt.com/archive/index.php/t-82556.html?

http://www.nyfaa.org/documents/Interfacing_Elevators_Sprinklers_and_Fire_Alarm_Systems.pdf

It seems that the shunt trip power should originate at the fire alarm panel.

 

[roger]

It seems that the shunt trip power should originate at the fire alarm panel.

That is not the case of any elevators I have done. I usually feed it from the elvator machine breaker itself or an external 120 v source with a breaker lock.

Roger

 

[George Stolz]

I didn't see in the attached threads where anyone said the shunt should originate at the fire alarm panel...?