0
What is the reason for using 250 percent multipler for sizing motor circuit breakers in NEC?
Wiki User
∙ 11y ago
When a motor starts the circuit breaker sees an almost dead short. Until the motor starts generating a back EMF , which opposes the current flow when rotation starts, the current is high.
If the breaker is sized to the motors full load amperage, each time the motor is started, the breaker will trip.
Wiki User
∙ 11y ago
Add your answer:
Earn +20 pts
Will multiple tripping of a circuit breaker damage the circuit breaker?
You don't specify whether you mean low-voltage circuit breakers, such as MCBs (miniature circuit breakers) or high-voltage circuit breakers. In either case, repeated tripping under fault conditions causes arcing which damages the main contacts of the circuit breakers. For this reason, high-voltage circuit breakers are taken out of service after a specified number of tripping operations, so that the contacts can be maintained or, if necessary, replaced. MCB contacts are inaccessible, and the MCB may eventually require replacing.
What is a difference between 10KA and 22KA circuit breakers?
The previous answer is incorrect, and I would advise that user to not give out information if they are going to give completely misguided information. The interrupting rating of a breaker is the maximum current that the breaker is designed to handle, at the breaker's rated voltage, before damage will occur to the breaker. A breaker will trip at FAR LESS than the interrupting rating, but it is extremely dangerous to expose the breaker to any situation where it will have more than the rated interruption current. the breaker is designed for. The reason some breakers are rated at 22kA instead of 10kA is because they typically have far larger conductors hooked up to them, so with the lowered impedance on the circuit there is more of a chance for the breaker to experience a higher fault current at the breaker. So electricians install 22kA breakers to handle the higher "available fault current."
What circuit breakers will interchange with white Westinghouse?
It is not recommended that different companies breakers be interchanged. Any field changes to the original manufacturer's equipment is not allowed due to electrical code rules. If a fault occurs and the result is a fire, your insurance company might not pay out for damages.
Why negative control is adopted in DC system And why DC circuit breakers are kept at the negative side?
The answer is: They are not. Whosoever told you that is off his meds. Alternatively, in some special applications there may be a reason for it. Many DC systems use a common ground where the loads are encased in the ground (like starter motors). Thus all breakers are positive, but some don't. If the loads don't care about polarity and the positive and ground are not common (like with a metal chassis), positive and negative is irrelevant.
How do you find out the reason why the motor trips the Ground Fault Circuit Interrupter when starting?
GFI Breakers are designed to an entire system of Receptacle's. they work by tripping any time there is an over load in the system , shorts and quick changes in current. make sure there isn't anything on other receptacle's. still occurs, put the load on it's own breaker..
Will multiple tripping of a circuit breaker damage the circuit breaker?
You don't specify whether you mean low-voltage circuit breakers, such as MCBs (miniature circuit breakers) or high-voltage circuit breakers. In either case, repeated tripping under fault conditions causes arcing which damages the main contacts of the circuit breakers. For this reason, high-voltage circuit breakers are taken out of service after a specified number of tripping operations, so that the contacts can be maintained or, if necessary, replaced. MCB contacts are inaccessible, and the MCB may eventually require replacing.
Why does a 100 amp circuit breaker panel have 30 breakers that are 20 amps?
There is no reason, it is most likely what the the installer did.
Why you are using dc in spring charge motors?
Presumably, you are describing the spring-charging mechanism on high-voltage circuit breakers? If so, then the reason is because, in the event of an electrical fault in which the substations loses its a.c. supply, the circuit breakers can be recharged from the standby d.c. batteries.
What important job do both fuses and circuit breakers do?
The reason to have a fuse or circuit breaker in the circuit is to protect the amount of current that can be applied to a conductor. Individual wire sizes are rated at specific amperages that they are allowed to carry. By allowing more amperage on an under size wire will cause it to heat up, sometimes to a point where the insulation can be destroyed. On a fault current this can quickly escalate to thousands of amps. Fuses and breakers prevent this high amperage from doing any damage by opening the faulted circuit.
What is a difference between 10KA and 22KA circuit breakers?
The previous answer is incorrect, and I would advise that user to not give out information if they are going to give completely misguided information. The interrupting rating of a breaker is the maximum current that the breaker is designed to handle, at the breaker's rated voltage, before damage will occur to the breaker. A breaker will trip at FAR LESS than the interrupting rating, but it is extremely dangerous to expose the breaker to any situation where it will have more than the rated interruption current. the breaker is designed for. The reason some breakers are rated at 22kA instead of 10kA is because they typically have far larger conductors hooked up to them, so with the lowered impedance on the circuit there is more of a chance for the breaker to experience a higher fault current at the breaker. So electricians install 22kA breakers to handle the higher "available fault current."
What circuit breakers will interchange with white Westinghouse?
It is not recommended that different companies breakers be interchanged. Any field changes to the original manufacturer's equipment is not allowed due to electrical code rules. If a fault occurs and the result is a fire, your insurance company might not pay out for damages.
Why air circuit breaker not using for ht lines?
The dielectric strength of SF6 gas compared to air at the same conditions (temperature, pressure, etc.) is approximately 2.5 times that of air. This means SF6 equipment can be made smaller (thus more cheaply), because the contacts do not need to separate as far. Oil circuit breakers are used for the same reason.
Do you have to pin breakers together when sharing the neutral on branch circuits?
Pinning breakers is becoming a thing of the past. This is due to the manufacturing of two pole breakers with one common trip reset handle. The electrical code states that on a 240 volt breaker if one leg trips the other leg must be disconnected from the supply also. This is a safety factor so that if they weren't tied together and one leg tripped the other half of the breaker would remain "hot". Any one working on that circuit in the tripped position could get a nasty shock from the un-tripped leg. Pinning the breakers on 240 volts was done because it was convenient to use single pole breakers in the distribution panel. To abide by the code the two single pole breakers were common tied together. When the branch circuits share a neutral to a common box they have to be common tied for the same reason above. This type of circuit is found on kitchen counter receptacles. Two separate circuits that share a neutral and go to separate junction boxes do not need the breakers tied.
What is the function of battery bank in a substation?
a very helpful functionAnswerBatteries are essential components in a substation. They provide the (tripping) current by which protective relays can trip high-voltage circuit breakers in the event of a fault. This means that the circuit breakers can trip even if the substation itself has lost its ancillary AC power supply.
How is an ammeter connected in a circuit in order to read the current flowing in the circuit?
In series with the circuit and never in parallel. The reason being that it will cause the circuit total resistance to drop which will make the circuit draw excessive current. That's a short circuit actually.
Why negative control is adopted in DC system And why DC circuit breakers are kept at the negative side?
The answer is: They are not. Whosoever told you that is off his meds. Alternatively, in some special applications there may be a reason for it. Many DC systems use a common ground where the loads are encased in the ground (like starter motors). Thus all breakers are positive, but some don't. If the loads don't care about polarity and the positive and ground are not common (like with a metal chassis), positive and negative is irrelevant.
Why won't the switch on my breaker box stay on?
This is properly understood when Ohm's Law is applied: Voltage, Amperege and Resistance are correctly applied to a circuit for it's correct function. The circuit breaker acts as a protective device and trips when a correct electrical circuit does not exist. The wrong breaker may have been installed. the wrong gauge of wire may have been used, the pumps and heaters may be drawing more amps then planned for or a short circuit or loose connection are all possible faults. Contact the electrician that installed the system for resolution of the problem or an outside electrician if the problem isn't corrected. Caution: Water and Electricity should not be trusted when in close proximity.
