2K amp GE Power Break 2 W/GFP

[hurk27]

This is going to be a little long so bear with me

Last month I had the GFP trip out a 2k amp breaker on a ground fault in a large theater with 15 screens and 1 I-Max.

This cause the theaters to go dark which freaked a few people out so state FM got called and I was called in to find out why the Emg lights didn't respond, ok here's what I found.

The breaker that tripped is on a 208/120 MDP fed from a 750kva transformer fed from a 900amp breaker in the 480/277 MDP main service with a 2k amp GFP main breaker also.

one of the first things noted is all the Emg lights are fed from the 277 volt systems so this was the reason why they didn't respond to the 208/120 going down, but when a movie is playing, each theater is lighted by LV runway lights from small transformers on the 120/208 system, and wall sconce's and cans up in the ceiling are on a dimmer pack controlled by the projector computers also fed from the 120/208 system.

So I pondered about 3 alternatives to light the theaters in the event of the loss of the 208 system:

1 install UPS systems on the LV lighting and cans in each projector room.
2 re-supply the Emg lights from the 120/208 system
3 shunt trip out the 277/480 from the 120/208 system

Bet you can guess which one they chose to do
Yep shunt trip it is.
the first two being that this complex is so vast and large the cost was quite high.
Bad thing was option 2 at the time of install would have not cost anything extra if someone would have caught it!!!!

To touch on why the GFP tripped was because someone thought doing the panel coordination study and setting the GFP on the 277/480v main was enough and left the GFP on the 120/208 set to the low factory settings which left the main set to 150amps GFP, a line to ground fault in a cord to a popcorn machine caused the ground fault that was on a 2-pole 50 amp breaker, in a 225 amp sub-panel fed from the 120/208v MDP, nether the 2-pole 50 or the 225 amp breaker tripped which is what led me to look at the GFP settings.
They had a panel coordination study done and the GFP properly set.

We had them get a GE engineer out to assist in figuring out a way to trip the 277/480 main out from the 120/208 system, well this is where it all went down hill, with out looking the GE EE assumed the power break main had the modules in them and the auxiliary contacts installed in them, so they had us order a shunt trip module, and a under voltage module, alarm bell module.

All sounded right, as I had no idea as to how the under voltage module worked in a GE system assuming it monitored all 3 phase and would have a dry contact to trip the shunt trip breaker, at least this is what I thought???

Nope not this thing, it requires a 24 volt DC control voltage to be supplied to its two terminals, ok called GE tech and asked where do I get this from, they replied from the 120/208 system via a 24 volt power supply, Oh and get this the UVR goes into the 277/480 main because when the 24vdc drops below 60% it trips out the main

Ok so I said let me get this straight when the 120/208 loses power the power supply loses power and this UVR trip the main in the 277/480 system right, he said yep, ok so to power back up the 277/480 main I just charge it and turn it back on and the UVR resets, (this is where it get interesting) he says no, I have to have 24vdc applied to the UVR before I can reset the main on the 277/480??? I ask him now since the 480 in down where do I get 24vdc from??
he tells me from the 208 system, I ask how since it is supplied from the 480 system, the phone went dead quiet after a few another GE EE gets on, and I go through the whole story again,

Finely I just asked them if the shunt trip will trip the 480 main if I apply a 24 vac to it, and he said yes, so I said no problem I'll get it done TY and good bye.

So I drew up a little diagram for a couple relays and a transformer and it worked flawlessly, now I hope it passes state

The attached diagram is simple:
a 100va 277/24 v transformer supplies the trip control power, relay 1 normally closed contact is the 120/208 monitor to signal the 480 main to trip, the time delay on is used to prevent false trips during normal power failures by opening the 24 volts to the trip circuit for 3 seconds, and allow resetting the system after a 120/208 loss trip out, of course the breaker supplying the transformer will have to be shut off till the 120/208 main is reset, but this was the simplest way I could see to do this job?

For discussion:
1 Has anyone else ran into an oversight such as this?

2 does anyone else know of a simpler circuit or a change to mine that would not require the breaker feeding the transformer or 24 volt supply to be shut down till the 208 is brought back up? remember the 120/208 is fed from the 277/480?

3 Has anyone else had these kind of problems dealing with GE engineers?

$ how do you recover the $480 when I try to return the UVR to the supply house when this was a miss ordered item caused by a request from GE them selves??? they are going to want a re-stock fee?? should I tell them to get it from GE?

Ya I got frustrated over this one.

 

[wireguru]

i thought emergency egress lighting had to be supplied from the same circuit or panel as the lighting so things like this dont happen.

 

[hurk27]

Funny thing is, they are, kind of

in the T-bar ceiling about 30 feet up is 4 4' lay-in's with 4 56w t-5 lamps in each, these are used in cleaning each theater and are controled by timers in the cleaning supply rooms, and the emg lights are on these circuits which are 277 volt.

But these are never on during a movie, go figure:roll:

 

[zog]

Keep in mind GE engineers are employed by GE and thier job is to make GE money. Not picking on GE, but that's is the way it goes with OEM support teams and the reason 3rd party firms exist and thrive.

 

[wireguru]

Funny thing is, they are, kind of

in the T-bar ceiling about 30 feet up is 4 4' lay-in's with 4 56w t-5 lamps in each, these are used in cleaning each theater and are controled by timers in the cleaning supply rooms, and the emg lights are on these circuits which are 277 volt.

But these are never on during a movie, go figure:roll:

I figured that. Seems like a failure in the design process. Wouldnt it have been easier and cheaper to stick a 120v coil contactor (supplied by the 120/208Y panel) in the 277v supply to the emergency lights? Then when 120v is lost, contactor opens, EM lights think power is out and come on?

 

[hurk27]

I figured that. Seems like a failure in the design process. Wouldnt it have been easier and cheaper to stick a 120v coil contactor (supplied by the 120/208Y panel) in the 277v supply to the emergency lights? Then when 120v is lost, contactor opens, EM lights think power is out and come on?

Yep a big failure in design!:roll:
If that was cost effective why not just rewire the emg fixture to 120 volts and save the contactor? almost all emg fixtures and ballast are dual voltage, 120/277, but remember, in the theater we have a stair stepped seating, and getting up there to these fixtures takes removing many of the seats, either setting up scaffold or a very small man lift, none of the 277 circuits run close to the 120 volt circuits so much piping would have to be done to interconnect the two systems, not to mention again, there are 15 regular theaters and then there is a much larger I-Max.

So it would have not been an easy job.
as for the shunt trip, I have less then 12 hours in it, just the frustrating part with the manufacture that shouldn't have been a problem if they knew what their own equipment actually did

but like I said, the little circuit worked and if the 208 goes down it trips the 480 main and brings on all the EMG lights through out the building.

 

[dbuckley]

Of course, if when this happens again, then since the emerg lights have come on, once the power is back up (or more correctly, once someone resets the shunt trip) then the lights will need time to recharge before acheiving their 100% charge state, and during that time the cinema will have to remain shut.

Which is a self inflicted wound.

Option two is the better answer, but still doesn't get around the recharge, so actually, there is no great answer!

 

[hurk27]

Of course, if when this happens again, then since the emerg lights have come on, once the power is back up (or more correctly, once someone resets the shunt trip) then the lights will need time to recharge before acheiving their 100% charge state, and during that time the cinema will have to remain shut.

Which is a self inflicted wound.

Option two is the better answer, but still doesn't get around the recharge, so actually, there is no great answer!

I agree with the option 2, but as I said I had to let them and the FM make the decision of which choice to make.

I guess one of the purpose of this post was to bring attention to problems like this, so this could be caught in design phase rather then 3 years after the place has been in operation.

As far as the "not opening back up till the battery's have recharge" LOL ya right, like that happens after a power failure:roll:

 

[hurk27]

To add a small note:
When I spoke to the EE who had his stamp on the design of this place, his first responce was "Why didn't the GFP on the 480 v main trip on the 208 ground fault?"

I was shocked when he asked this!!!

I had to explain how a GFP on the line side of a SDS will only see line to line current of a load side GF????

 

[hurk27]

Ran the full test today for the FM, worked like a dream, and also found that I don't have to kill the 24 volt supply after a trip, since I can charge and reset the 120/208 main then charge and reset the 277/480 main and it all comes back up, as the 3 second delay keeps it from retripping the main.

FM signed off so it was good to go

 

[__dan]

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I'm a little surprised your post did not get more replies. Dumping the main and the whole megaplex load has a large set of unpredictable consequences. The assumption would be the main has to stay closed except when it is serving its essential purpose, protective device or hazard isolation.

I would not place myself in the position that if the main trips it was my wiring that caused it. There are too many other essential client and client customer systems that need power to operate. Dumping the main to force the battery lights on is out, unthinkable, too many things to worry about liabilitywise

1. It seems like the existing was OK per code, if power was lost on the 277 v lighting circuits, battery EM lights were there for emergency egress lighting.

2. Power was lost on 110v accessory 'show' lighting, actually all of the 110 v loads. Once this outage was discovered, were the house 277 v lighting available for manual control, could they be turned on with switch or command. If the 277 v house lights were available and simply not turned on, that's operator error, not necessarily a wiring or code issue. If the house 277 v lights were disabled because of 110 v loss at the lighting control computer, the computer needs to be on a UPS, not the lighting load itself.

3. Looking for an auto control scenario when 277 v is available and 110 v is not, I would consider placing inexpensive definite purpose contactor contacts in parallel on the 20 amp 277v lighting branch circuits. Place the contacts in parallel with the normal lighting load switching devices contacts and close contacts when power is lost on the monitored 110 v triggering circuits. If the panels are adjacent in the same room the wiring may be economical.

4. I would also probably offer to install some 120 v EM lights on the 120 v show lighting circuits.