# Breaker Failure Protection (50BF)

#### Mehboob

Dear,

In our G60 (Generator Protection) Relay, 50BF is pick many times, what could be reasons.

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#### CSA

Mehboob,

Breaker failure protection can take many forms. In my experience, it's usually a means of monitoring the electrical circuits that can be used to close and--most importantly--open ("trip") a critical circuit breaker. And, often, a loose wire or a bad crimp or a bad connection or a failed or failing close- or trip solenoid can cause these repeated "failure" alarms.

Best to get this problem investigated and resolved as quickly as possible--because an inability to open a critical circuit breaker can result in very serious damage, and even harm or death to nearby humans...!!!

#### PhilCorso

Mehboob
1) Regarding the Gen'r "CB-Failed-To-Operate" Function, can you provide the 27 (Voltage-Relay) and 50 (Overcurrent-Relay) Logic diagram?
2) Do you also have a Gen'r "CB-Inadvertently-Operated" Function?
Regards, Phil Corso

#### PhilCorso

Mehboob
It is very unlikely that false tripping is caused by the Input devices, i.e., the 27 or 50, because the probability of 2 input-devices failing simultaneously is extremely low. I suggest you address the BF output-action device or circuit, especially the timer, if so equipped.
Additionally, try to correlate the time of the false-trips, to other physical occurrences, as CSA suggested, like slamming of a cabinet door, or movement of a heavy truck in the vicinity of the building housing the equipment.
I remember an incident where every time someone passed thru a door in a wall on which a relay cabinet was mounted the power plant tripped. The fix was to nail the door shut using 2x4's !
BTW, if anyone is interested in ridiculous false-trip situations search Automation.Control archives ! The most exciting one for me was false-tripping of an LNG plant during 2nd shift-change on Tuesdays. Went on for weeks ! It resulted in a 100-M$, 400-ft flame, on a 400-ft stack, in the middle of a very popular tourist location ! Regards, Phil Corso Thread Starter #### Mehboob Mehboob, Breaker failure protection can take many forms. In my experience, it's usually a means of monitoring the electrical circuits that can be used to close and--most importantly--open ("trip") a critical circuit breaker. And, often, a loose wire or a bad crimp or a bad connection or a failed or failing close- or trip solenoid can cause these repeated "failure" alarms. Best to get this problem investigated and resolved as quickly as possible--because an inability to open a critical circuit breaker can result in very serious damage, and even harm or death to nearby humans...!!! Breaker close or trip is Ok. This event come again and again while running of generator without causing any type of trip. As per my knowledge this should be active when any trip signal is generated to trip beaker if breaker is not triped due to any reason this send command to other breaker to isolate. Thread Starter #### Mehboob Mehboob 1) Regarding the Gen'r "CB-Failed-To-Operate" Function, can you provide the 27 (Voltage-Relay) and 50 (Overcurrent-Relay) Logic diagram? 2) Do you also have a Gen'r "CB-Inadvertently-Operated" Function? Regards, Phil Corso CB never failed to operate. Thread Starter #### Mehboob Mehboob It is very unlikely that false tripping is caused by the Input devices, i.e., the 27 or 50, because the probability of 2 input-devices failing simultaneously is extremely low. I suggest you address the BF output-action device or circuit, especially the timer, if so equipped. Additionally, try to correlate the time of the false-trips, to other physical occurrences, as CSA suggested, like slamming of a cabinet door, or movement of a heavy truck in the vicinity of the building housing the equipment. I remember an incident where every time someone passed thru a door in a wall on which a relay cabinet was mounted the power plant tripped. The fix was to nail the door shut using 2x4's ! BTW, if anyone is interested in ridiculous false-trip situations search Automation.Control archives ! The most exciting one for me was false-tripping of an LNG plant during 2nd shift-change on Tuesdays. Went on for weeks ! It resulted in a 100-M$, 400-ft flame, on a 400-ft stack, in the middle of a very popular tourist location !
Regards, Phil Corso
Dear Sir,

No tripping just command come and drop out.

#### PhilCorso

Mehboob
I misread your comments. Perhaps you can utilize my procedural tips to find the cause of the false-alarms?
Regards, Phil

#### CSA

Mehboob,

"As per my knowledge this should be active when any trip signal is generated to trip beaker if breaker is not triped due to any reason this send command to other breaker to isolate. ..."

Let's analyze this statement part by part. "...this should be active when any trip signal is generator to trip breaker if breaker is not tripped due to any reason ...." All the more reason the unit should NOT BE running until this problem is investigated. If there is a signal which is trying to trip (open) the breaker and the breaker is not opening (tripping) then this is a HUGE PROBLEM.

"... this send command to other breaker to isolate. ..." If this alarm condition is active (meaning it's sending a command to another breaker to open and isolate the generator breaker and the other breaker is not opening (tripping) then this is an even HUGER PROBLEM!!!

Much as I dislike doing it, you need to follow Phil Corso's advice and employ a logic process of finding out what is causing the alarm condition that is NOT tripping any breaker. And, that should begin with ensuring your knowledge is correct: That, indeed, this should be active when the breaker is being told to open (trip) but is not, and if the breaker does not open (trip) it sends a command to another breaker to isolate (open; trip) and that is not happening.

Troubleshooting is often a process of elimination. One takes a look at a problem, makes sure they understand the way the equipment or protection scheme is supposed to work, then decides--using knowledge and experience--to start the investigation "here" or "there" (often there are several possibilities, so one has to decide it's more likely for "this" ("here") to be a problem than "that" ("there"). And using a logical process one works through each possibility, proving this or that does or doesn't work until the conclusion is arrived at. If one exhausts all the possibilities of "here" without finding a problem, then one shifts their attention and focus to "there" and in the same logical process one eliminates all the possibilities until the cause is found--and then resolved.

Breaker failure can mean many things--it sound's so simple, doesn't it? In my experience it is looking for the presence of voltage and a path for current to flow in the breaker trip (open) circuit(s). In your case, you believe (but don't seem to have proven for this particular case--one of the first steps in troubleshooting!) that this alarm will be annunciated if something is trying to trip (open) a breaker but the breaker has not opened AND it will send a signal to another breaker to open (trip). BOTH of those things are VERY CRITICAL. The point is: Breaker failure doesn't always mean the same thing at every site! And if you're not sure, and it doesn't sound like you really are sure, then the first thing to do is make sure you understand what is supposed to be happening.

This idea (which is pervasive) that as long as the unit doesn't trip and continues to run when an alarm is generated is very, Very, VERY DANGEROUS. It's high-stakes risk-taking. In this case, if you belief is correct and the breaker should have tripped (opened) but it didn't AND another breaker should have opened to protect the first breaker/circuit and it didn't open (which you are implying should occur--but hasn't), then there are TWO failure, both of which can have very serious, even deadly, consequences.

Phil Corso has presented one situation which ended pretty badly. Can you risk your situation ending badly, too?

Please write back to let us know what you find.