- Location
- Massachusetts
NAC one brand calls them SNAC.
Why do they both trip???
- Thread starter iwire
- Start date
- Status
NAC one brand calls them SNAC.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
All true, but no one calls the main fire pump or booster fire pump service a "fire alarm booster panel", "FA supply", or "fire alarm control panel". Not to mention they wouldn't be coming out of a distribution panel in any event.
Apparently you have not read the thread before commenting
I actually posted the data sheet link in this thread, not clear, but no mention is made of the oc element
The op said the are sc/instant only, no toc element
mag only is not uncommon on motor applications
or fire pumps
in mining they are the standard and are usually supplemented by an external OL pack
disagree
never heard a fa panel referred to as a 'booster' panel (btw, that word is not used in the panel schedules)
been to the following schools: Ansul, Fenwal, Kidde, Pyrotonics, Edwards, Honeywell, etc.
Worked for a firm for 4 years that did a large amount of work with fire/explosion suppression/detection (along with power dist) in the oil fields of Alaska, military facilities, telecomm facilities and Boeing facilities in WA: Seatronics Protection Systems
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
I even went so far as going to a GE website to look at the breaker curve. However before I got to the TCC, the data sheet said this SFLA breaker came with: Trip Function LSI. Designated by the letter T in the part number.
- Location
- Massachusetts
You probably should drop this and move on. It is not pertinent to the conversation. Furthermore the fact I wrote it gives me 100% confidence it had nothing to do with a motor.
There are no motor loads.
we should both drop it
no motor loads anywhere on the system? or only downstream of the subject cb's?
as many have said:
turn the breakers up to a more reasonable setting, will not harm a thing since they have oc protection and will still be at a reasonable level (plus it doesn't cost anything but some time)
who knows what transients/reflections are being generated, on the line or load side
it sounds like the following has been eliminated:
cables are sound
no loads that would cause transients in excess of 300% of the rating
no correlation to generator transfer
no oc since loads are << than the setting and hold for days (or longer)
turning 2 breakers up at a time may isolate the offending circuit
what else is left?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Yes page 6-47 includes the code for the part number.
Did you look at page 6-91?
The letter T, in position #8, indicates the breaker has Long time (e.g. thermal) tripping. There would be a letter I here, if this was a Motor Circuit Protector frame for magnetic only protection.
310 BLAZE IT
Senior Member
- Location
- NJ
I if we're being 100% technically correct let's call it a transient.
pg 6-47 also shows a note for the T code as LSI an industry std term for LongShortInstant
and transients can be incident/refracted/reflected
we are assuming it is coming from the loads, could be on the supply, and since set so low is tripping first, then the 2 branch breakers
a wave hitting a xfmr is reflected almost 100% so the source sees twice the magnitude of the incident wave in the load reflected wave
imo they are all set too low
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Just like I noted in post #185.
It appears that you heard hoof steps and thought of Zebras instead of horses.
I think it is time to stop digging. and look back to what the OP has posted throughout this thread.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Actually the pressure maintenance pump can be supplied from the normal service or the fire pump service, but I otherwise agree you almost never hear it called a "fire alarm" anything, maybe a "fire pump" something though.
you didn't even hear the hoof steps apparently
why is what you think more important than what I think?
if the info presented is accurate there is no solution so the client must live with it:
no abnormal switching transients can be identified
no faults on the system
the breakers are set correctly and can't be set higher for some reason
I would selectively set breakers higher to identified which branch was the source (main, 70 or 100)
or just set all higher to 800-1000% and call it a day
300% is way too low
the 70 has perhaps 8 A (feeds a 45 kva transformer loaded to ~ 6 kva)
the 100 has 25 A (feeds a subpanel that feeds a small 7.5 kva xfmr loaded to 1 kva)
imo the problem is on the supply side (and interaction with the xfmrs)
but in reality the problem is the 300% setting
illogical
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
:thumbsup:
For pretty much any inductive load that is placed "across the line" when energized. Sure it may hold sometimes, or even quite a bit of the time but that is low enough you can't expect it to hold every time.
- Location
- Massachusetts
That is a strawman, no one has said that at all.
So you are good without finding the reason they are tripping and simply cranking up settings.
Duly noted.
ptonsparky
Tom
- Occupation
- EC - retired
Sounds like a plan from this side of the river.:huh:
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If you replaced them with a breaker that didn't have magnetic trip adjustment, chances are the fixed magnetic trip is at least 600 or even 800% of the breaker rating.
I really don't know you can turn them too high from a overcurrent protection perspective, any specific setting you do put them at is for selective coordination purposes - with the intent that the branch breakers will trip before the main does if there is a fault on a branch circuit.
If you turned the main up, I'd bet your random tripping event ends up only tripping the branch breakers.
If you turned up the branch units but not the main, you probably only see the main trip during whatever event is occurring.
How much to turn each one up is for selective coordination, they are still going to protect the wiring from short circuits and ground faults even at maximum settings.
I really don't know you can turn them too high from a overcurrent protection perspective, any specific setting you do put them at is for selective coordination purposes - with the intent that the branch breakers will trip before the main does if there is a fault on a branch circuit.
If you turned the main up, I'd bet your random tripping event ends up only tripping the branch breakers.
If you turned up the branch units but not the main, you probably only see the main trip during whatever event is occurring.
How much to turn each one up is for selective coordination, they are still going to protect the wiring from short circuits and ground faults even at maximum settings.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Let me say this assumes what is there already is in compliance with the available fault current and AIC ratings as well as any series ratings for downstream devices.
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