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Not normally. They are sized slightly above the LRA ( locked rotor amps) or the FLA (full load amps) stated on the motor nameplate. The startup current of a motor can be 125-150% of the running load amperage. This depends on the motor, its EFF (efficiency) and the torque requirement of the load.

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What size breaker for a 3 phase 460 volt 50 hp motor?

Breakers are sized by the conductors that are connected to them. Conductors are sized by the amperage that the load draws. The electrical code states that a 50 HP 460 volt three phase motor draws 65 amps. The ideal amperage would be taken from the motors nameplate as different motors of the same horsepower will have different amperage's depending on what they are designed to do. The feeders for this motor have to be sized at 125% of the motors full load amperage. 65 x 125% = 81 amps. A #4 copper conductor with and insulation rating of 75 or 90 degrees C is rated at 85 amps. The breaker for this motor is 150 amp or 175 amp fusing or 110 amp time delay fusing.


What is the full load running current of a 3hp 208volt single phase continuous duty ac motor?

It would probably be 20-30 amps. <<>> The electrical code book states a value of 18.7amps for a 3HP 208 volt motor. If the nameplate data is available it is always best to use it when calculating wire size and overload protection for the motor.


Which relay is used to control 3 phase induction motor?

Overloads for motors are sized from the full load amperage that is taken from the motors nameplate. Depending on who the manufacturer of the motor contactor is will govern the sizing of the relay. Some contactors use bolt in heaters and others use a separate unit that connects to the contactor. No matter what method is used make sure to use the manufactures recommended overloads that are based in the motors FLA.


How do you size the circuit breaker feeding a soft starter for a 195A full load current induction 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.


How many amps does a 2 hp 240 volt single phase motor draw?

One horsepower electric is defined as 746 watts, so two horsepower is 1492 watts. Divide that by 240 volts, and you get about 6.2 amperes. Now you have to consider the power factor, which is the ratio of apparent power to true power, caused by the inductive (reactive) load of the motor causing the current to be out of phase with respect to voltage. You did not say what the power factor was, so lets assume it is 0.8. That makes the current about 7.75 amperes.That's running current, at full load. Starting current is often four times higher. The NEC list this motor has drawing 12 amps and to wire this motor you would use this value, unless the actual nameplate amps on the motor was higher.

Related Questions

Are motor conductors sized to the locked rotor current?

According to 2011 nfpa 70 nec Motor conductors are sized with the flc- full load current or the nameplate rating fla- full load amperes


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%.


What does no load speed on a electric motor mean?

Generally a motor drives some equipment, it could be a fan, or a pump, connected to motor's shaft. The speed of the motor when no equipment is connected to its shaft is known as no load speed.


How do you connect a single phase 220v motor to the breaker box?

Before the motor is connected to the distribution panel supply, overload protection should be considered. Some motors have their own internal protection and it will state "motor thermally protected" on the motor's nameplate. There is usually a red reset button on the end bell of the motor. A manual motor starter is the next option if the motor is not self protected. These types of starters have overload protection heaters that are rated for different amperages depending on what the motor's full load amperage rating is on the nameplate. Now to the question, in North America you would select to adjacent full size breakers (not mini breakers) in the distribution panel. The two pole breaker is sized on the current draw of the motor. Because of the motor's inrush current the breaker is sized at 250% of the motor's full load amps from the motor's nameplate. The wire sizing has to be 125% of the motors full load amps.


What size breaker for a 3 phase 460 volt 50 hp motor?

Breakers are sized by the conductors that are connected to them. Conductors are sized by the amperage that the load draws. The electrical code states that a 50 HP 460 volt three phase motor draws 65 amps. The ideal amperage would be taken from the motors nameplate as different motors of the same horsepower will have different amperage's depending on what they are designed to do. The feeders for this motor have to be sized at 125% of the motors full load amperage. 65 x 125% = 81 amps. A #4 copper conductor with and insulation rating of 75 or 90 degrees C is rated at 85 amps. The breaker for this motor is 150 amp or 175 amp fusing or 110 amp time delay fusing.


What is the full load running current of a 3hp 208volt single phase continuous duty ac motor?

It would probably be 20-30 amps. <<>> The electrical code book states a value of 18.7amps for a 3HP 208 volt motor. If the nameplate data is available it is always best to use it when calculating wire size and overload protection for the motor.


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.


Which relay is used to control 3 phase induction motor?

Overloads for motors are sized from the full load amperage that is taken from the motors nameplate. Depending on who the manufacturer of the motor contactor is will govern the sizing of the relay. Some contactors use bolt in heaters and others use a separate unit that connects to the contactor. No matter what method is used make sure to use the manufactures recommended overloads that are based in the motors FLA.


How do you size the circuit breaker feeding a soft starter for a 195A full load current induction 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.


How many amps does a 2 hp 240 volt single phase motor draw?

One horsepower electric is defined as 746 watts, so two horsepower is 1492 watts. Divide that by 240 volts, and you get about 6.2 amperes. Now you have to consider the power factor, which is the ratio of apparent power to true power, caused by the inductive (reactive) load of the motor causing the current to be out of phase with respect to voltage. You did not say what the power factor was, so lets assume it is 0.8. That makes the current about 7.75 amperes.That's running current, at full load. Starting current is often four times higher. The NEC list this motor has drawing 12 amps and to wire this motor you would use this value, unless the actual nameplate amps on the motor was higher.


Phase Converter Shopping Guide?

A phase converter is a rotating machine, quite similar to a motor. The machine converts single-phase utility power into 3-phase electricity for use by 3-phase equipment. We use a phase converter where 3-phase utility is unavailable, or when it is too expensive for us to install. A properly sized and purposefully chosen phase converter is an economical option that will operate any load as well as the utility 3-phase will, and a high-quality phase converter provides an ample lifespan. The primary decision the consumer must make is the choice between a rotary or a static phase converter. Rotary 3-phase converters are the most reliable type of converter, and they are the most flexible. They produce true 3-phase power, and thus they operated any type of load or combination of motors. Static 3-phase converters do not generate true 3-phase power, and are very similar to an electric rope starter. Once the motor is started, static converters cannot balance the load between the three legs. Therefore, using a static phase converter, the motor is never able to develop full horsepower. However, they are suitable for heaters, rectifier loads and single motor, small horsepower applications. The benefit of the static 3-phase converter is that it starts quickly, and it is substantially less expensive than a rotary phase converter. Therefore, if for your application, the motor can run at 70% of nameplate horsepower, and you start it infrequently, a static phase converter is a great choice. By infrequent, we mean less than four starts per hour. Customers must know that there are no industry standards that apply to phase converters. This means a couple of things for the consumer. One, the price between similar models can vary drastically. Two, low quality phase converters are far more trouble than they are worth. Make it a point to research phase converter brands, and pay the premium, if necessary, in order to get a high quality model of the type you require. In addition, never compare phase converters solely on the nameplate horsepower rating. Ask for the NEMA frame size, and then compare phase converters of equal frame size. Marketing often suggests that you can achieve similar/same output from a small frame size. This is impossible, so keep that in mind, and ignore the clever marketing.


What sezi cable can you use to connect 10amps motor 3 phase?

14/3 copper with ground on a 25 amp breaker Before I get chastised for recommending that 14 gauge wire be protected with a 25 amp breaker, which would be in violation of standard wiring requirements, Sec. 240.4(G) of the NEC tells us that the standard wiring requirements, i.e. 15 amps on 14 gauge wire, does not apply to motors. Table 430.52 tells us that an inverse-time circuit breaker (that's a standard type breaker) can be set to 250% of the FLC of the motor and 430.22 tells us that the branch circuit conductors are sized at 125% of FLC. The question does not say that 10 amps is the FLC. The nameplate rating of a motor is not the FLC. FLC is determined by using the tables in Sect. 430. The name plate rating is used only for sizing current overloads, called "heaters". For my answer I have assumed 10 amps is the FLC.