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You have to be careful with terms in the electrical field, Example: Main Feeder Circuits will feed a Transformer for distribution and each of those main circuits might feed numbeous Motor control centers. However each of those circuits could be called a main feeder for the motor control center. Confusing. We have High Voltage Transmittion tansformered down for Distribution. So normally a Feeder Breaker will feed Main circuits that will be used for distribution. Example Your home panel will have a main feeder circuit to the whole panel and distribution breakers to you home.
Wiki User
∙ 15y ago
Wiki User
∙ 12y agoFeeder breaker is protecting the supply and the wiring. Motor breaker is protecting the motor.
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How do you choose circuit breaker all the control circuit if i have 50kw power of motor?
The breaker should be sized to 250% of the motor's full load amperage.
What is Selection procedure for motor protection circuit breaker?
The selection of overload protection for motors is taken from a table in the electrical code book. It is based on the full load current rating of the motor.
What is the reason for using 250 percent multipler for sizing motor circuit breakers in NEC?
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.
Cause of a circuit breaking tripping?
Tripping is caused by excessive current, which is usually the result of a fault in cable or equipment. The circuit breaker is there for safety and it trips to prevent a possible fire starting.
How do you calculate breaker capacity of 10 hp three phase induction motor?
The first thing you have to do is find the full load amps of the motor. The wire size feeding the motor has to be 125% of the full load current. The breaker is usually 250% of the full load current. If the voltage and amperage had been added to the question the exact breaker size could have been calculated.
What size breaker is needed for a 125 hp motor?
It depends on what the amperage of the motor is. The motors amperage depends on the voltage of the motor. The higher the voltage the motor operates on the lower the amperage. So unless the amperage from the motor's nameplate is stated an answer can not be given.Just remember that the feeder capacity to the motor has to be 125% of the motors full load amperage and the breaker protecting the conductors to the motor has to be rated at 250% of the motors FLA. This higher breaker size allows the motor to start without tripping a normal size breaker that is rated for the lower conductor size.
Looking for a basic standard type answer to how many circuit breaker amps are needed per motor horsepower on 3 phase?
The main breaker is not based on the HP of the motor it is based on the FLA of the motor. Many different motors have different characteristics and all of the different motors have different amperages Once you have the amperage of the motor the breaker is 250% times the FLA of the motor.
Is the circuit wiring between the motor starter in a motor control center going to the equipment disconnect with a circuit breaker in it a feeder or a branch circuit?
The terminology for a feeder is any wire that is coming into a device (it feeds the device with power). A feeder will be the wire coming into the disconnect and also the wires going into the motor will be called feeders. Even the wires coming into the MCC will be termed feeders. Branch circuits are circuits that usually originates at the main distribution and spread outward to their respective loads. Branch circuit terminology encompasses all of the equipment in the circuit that is connected from the overload device to the field load device.
What size circuit breaker is used for a 10000 watt single phase cooler with 240 volts?
The equation for amperage is Amps = Watts/Volts = 10000/240 = 41.6 amps. It is not stated if this is a motor load or not. If it is a motor load then the feeder has to be rated at 125% x 41.6 = 52 amp wire. Also if it is a motor load then the breaker will have to be 250% x 41.6 = 104 amps. A 100 amp breaker will work and still be within the electrical code ruling. Otherwise for 41.6 amps a 50 amp breaker will be sufficient.
What size amp circuit breaker should be used for a air compressor?
This is determined by the size motor and the amount of amps the motor draws, be on the safe side and consult the owners manual or an Electrician. <<>> The sizing of the breaker and feeder wire is based on the amperage of the compressor. Look on the name plate and find the amperage. The amperage on the nameplate then has to be multiplied by the motors full load amperage and that value is used for the wire size. Because the load is a motor the FLA is again multiplied by 250% to size the breaker. This takes into allowance the high starting current of a motor from 0 to 100% RPM.
What cause the Main Breaker trips when I start a 30KW 3-phase Motor(Star Delt Starter)?
The wiring is like this:[[30KW Motor ---- Star Delt Starter(100A Breaker inside) ----- 200A Breaker------50A Breaker(Inside the breaker box which located inside the factory) -----100A Main Breaker]]Once I try to start the Motor, the Main Breaker trips immediately.
Which calble use single 1 hp motor?
Motors with same horse-powers have different full load amps when operating. To calculate the size of wire to supply the motor feeder the voltage or current of the motor has to be known.
What size awg do you need to install a 240v rec on a 50a breaker?
#8. It is better to error on the next large size. # 8 THHN 90 degree wire is rated at 45 amps. If there is a possibility that the breaker is connected to a 50 amp load the wire will be undersized. A #6 wire is rated at 65 amps. For continuous use, a load factor of 80% has to be applied. 65 x .8 = 52 amps. The only time the conductor can be smaller than the breaker size is on a motor feeder. Then the breaker is sized at 250% of the nameplate full load amps (FLA) rating of the motor. This is to allow the motor's starting current, which is about 300% FLA, to not trip the breaker on start up.
How big of a breaker for a 26 amp motor?
Sizing circuit breakers for motors falls into a different category. Because of the inrush of current when the motor is in the stopped position, the breaker has to be sized to allow for this. Breakers usually are 250% of the nameplate full load amp rating. The wires that feed the motor are sized to 125% of the full load amps of the motor.
What amp breaker do you use for a three fourths horse garage door opener?
A 15 amp should be fine, provided that #14 wire is used for the outlet. If #12 is used, then use a 20 amp breaker. Depending on what the motor voltage is makes a difference on what the wire size is. A 3/4 HP motor draws 13.8 amps at 115 volts and 6.9 amps at 230 volts. The motor feeder conductor must have an ampacity at least equal to 125% of the full load current rating of the motor. 13.8 x 125% = 17.25 amps. The conductor required on a motor using 120 volts is #12 rated at 20 amps. The breaker for this motor needs to be rated at 30 amps.
What circuit breaker rating do you need for a 3 phase electric motor?
The circuit breaker is sized to the full load amps of the motor times 250%.
How do you choose circuit breaker all the control circuit if i have 50kw power of motor?
The breaker should be sized to 250% of the motor's full load amperage.
