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How can relay fail to send signal to circuit breaker to trip?
NanaDuah
A protective relay may fail to send a signal for many reasons - assuming it should have operated (so pickups, time dials, etc. are set so the relay should have operated), the relay may be out of tolerance, if it is a microprocessor based relay it may be in some state of failure or there may be a fluke situation that causes an element to hang up, if it is solid state, it's power supply may have failed (many solid state did not have any sort of monitoring for this condition). Battery power may not be sufficient to operate the breaker, or wiring to the breaker may be compromised (open test switch, lifted wire, rodent damage to wiring, etc.).
The analog connections to the relay may be bad, or wiring may have issues (such as multiple grounds on PT/CT connections). I've seen where a CT was supposed to be wye connected and one of the ground jumpers was missing, which caused some strange behavior.
A relay output contact may have failed as well - if not properly designed, these can get burned out fairly easily.
Microprocessor relays have an abundance of programming options; sometimes they get programmed wrong as well.
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Can circuit breaker isolate circuit?
That's just what a circuit-breaker is designed to do - Isolate a circuit from the rest of the system.AnswerNot necessarily. A circuit breaker is a protective device, designed to disconnect circuits in the event of an overcurrent due to overload or short circuit. While a low-/medium-voltage circuit breaker, of course, can be used to open a circuit, it does not necessarily provide isolation. In general, isolation requires a visible break in the circuit; as a circuit breaker's contacts are enclosed, a visible break is not possible.In the case of a high-voltage circuit breaker, the device is used to open a circuit but does not isolate that circuit from the supply. Isolation must be provided using separate,usually non-loadbreaking devices (i.e. devices which are not designed to open a live circuit) called isolators (UK term) or disconnector (US/Canadian term), which provide a visual break in the circuit. The exception to this is a racking-type circuit breaker which, after it has been opened, can be racked down from the circuits to provide a visual disconnection.
What one is better fuse or circuit breaker?
IMO it would be because the circuit breaker has the possibility of going bad and not working (allowing a short to move through the device), but fuses blow (cause a break) no matter what if shorted.
What is relay coil?
An electrical device, typically incorporating an electromagnet, which is activated by a current or signal in one circuit to open or close another circuit.Based on Characteristic the protection relay can be categorized as-Definite time relaysInverse time relays with definite minimum time(IDMT)Instantaneous relays.IDMT with inst.Stepped characteristic.Programmed switches.Voltage restraint over current relay.Based on of logic the protection relay can be categorized as-Differential.Unbalance.Neutral displacement.Directional.Restricted earth fault.Over fluxing.Distance schemes.Bus bar protection.Reverse power relays.Loss of excitation.Negative phase sequence relays etc.Based on actuating parameter the protection relay can be categorized as-Current relays.Voltage relays.Frequency relays.Power relays etc.Based on application the protection relay can be categorized as-Primary relay.Backup relay.Primary relay or primary protection relay is the first line of power system protection whereas backup relay is operated only when primary relay fails to be operated during fault. Hence backup relay is slower in action than primary relay. Any relay may fail to be operated due to any of the following reasons,The protective relay itself is defective.DC Trip voltage supply to the relay is unavailable.Trip lead from relay panel to circuit breaker is disconnected.Trip coil in the circuit breaker is disconnected or defective.Current or voltage signals from CT or PT respectively is unavailable.As because backup relay operates only when primary relay fails, backup protection relay should not have anything common with primary protection relay.Some examples of Mechanical Relay are-Thermal(a) OT trip (Oil Temperature Trip) (b) WT trip (Winding Temperature Trip) (C) Bearing temp trip etc.(a) Buchholz (b) OSR (c) PRV (d) Water level Controls etc.Float typePressure switches.Mechanical interlocks.Pole discrepancy relay.
What are the signs of a worn your circuit breaker?
They don't wear out for the most part,just fail to work. If something seems wrong,it is most likely the wiring,switch,outlet,or component.
Why do manufactures protect the Vehicle Headlight with circuit breaker instead of fuse?
Vehicle headlights are protected with circuit breakers instead of fuses because, when light bulbs fail, there is an ionizing arc internally that causes high current. You see that at home - when a light bulb fails you see an instant of very bright light.This pulse of high current can blow a fuse. It also can trip a circuit breaker, but the circuit breaker is designed to reclose while, once a fuse is blown, it stays blown. Headlights are a critical safety device. It is better to attempt automatic reclosure following a fault, than it is to leave the headlights off, in case the fault was temporary.
How do you calculate rated kva of a circuit breaker?
You don't calculate the rated kV.A of a circuit breaker; it's determined by the manufacturer. It's important that a circuit breaker's rated kV.A exceeds the fault level kV.A at the point where the circuit breaker is located, otherwise it may fail to interrupt a fault current and, possibly, self destruct.
How do you built a mains fail alarm?
Use an intermediary relay that is specifically and only connected to a circuit from a two pole breaker in the distribution panel. Through the N.C. contact of the relay connect your DC alarm system. As long as the power is on the relay stays energized and the N.C. contacts stay open. If a power failure occurs the relay will drop out and close the N.C. contacts. This will close the circuit on the alarm system.
Would a relay race be a good example for a parallel circuit or a series circuit?
A relay race would be an example of a series circuit. Since every runner relies on the runner before him/her to continue on, if one runner fails the rest of them fail. With a series circuit, if one part of the circuit fails, all of the parts before and after it fails. A parallel circuit does not completely fail if one or more of the parts fail.
Could the conductive pathway or signal be damaged in my circuit board, causing it to fail?
A short circuit on a motherboard can severely effect it's performance, causing it to fail. Something could indeed be wrong with the conductive pathway or signal.
Can circuit breaker be bad even getting little electricity?
Anything can go bad. A breaker is a mechanical device and can fail for many different reasons.
What would you conculde if you saw if one bulb burned and all lights fail?
The bulbs are in connected series. There was a short circuit and the circuit breaker tripped.
Can circuit breaker isolate circuit?
That's just what a circuit-breaker is designed to do - Isolate a circuit from the rest of the system.AnswerNot necessarily. A circuit breaker is a protective device, designed to disconnect circuits in the event of an overcurrent due to overload or short circuit. While a low-/medium-voltage circuit breaker, of course, can be used to open a circuit, it does not necessarily provide isolation. In general, isolation requires a visible break in the circuit; as a circuit breaker's contacts are enclosed, a visible break is not possible.In the case of a high-voltage circuit breaker, the device is used to open a circuit but does not isolate that circuit from the supply. Isolation must be provided using separate,usually non-loadbreaking devices (i.e. devices which are not designed to open a live circuit) called isolators (UK term) or disconnector (US/Canadian term), which provide a visual break in the circuit. The exception to this is a racking-type circuit breaker which, after it has been opened, can be racked down from the circuits to provide a visual disconnection.
If you install a 30A 240V GFI breaker will this be ok or will the cycles the dryer has prematurely fail the breaker?
I suspect you mean GFIC breaker. The dryer will not cause the breaker to fail.
What does fail safe mean for railroad circuits?
It means that if the circuit fails for ANY reason, the the signal aspect goes to red and all trains (controled by that signal) must stop.
What makes a circuit breaker go bad?
A circuit breaker can go bad from being tripped too many times. Many people don't understand that the tripping of a circuit breaker indicates a problem that needs to be corrected. They usually just reset the circuit breaker, leading to a very common second (or third, or fourth) trip. Circuit breakers tripping are for the prevention of fire due to excessive heat in the circuit. They're not supposed to be tripped repeatedly. This can wear the breaker out. Believe it or not, I've also seen circuit breakers fail to re-energize after being turned off. I speculate this was actually caused by the breaker never having been cycled (it was a main breaker), and the time elapsed since it was installed. Electrical equipment doesn't last forever. It's the same as anything else.
How many circuit breakers would a lightning strike trip?
Generally circuit breaker is not designed to trip off in the event of lightning. The system has lightning arrestors which reroute the lightning effect to earth instantly. If there are no lightning arrestors then the equipment are likely to fail upon a lightning strike.
Where is the relay for a blinker in an Oldsmobile alero?
The hazzard light switch on the dash to the right of the speedometer is also the turn signal flasher. This is a common part to fail if intermittant turn signal operation. - TechJK -----------------------------
