How Do You Determine Locked Rotor Current

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The Answer is There are two basic methods for determining the locked rotor current (starting current) of a squirrel-cage induction motor, depending on the information available.
If the motor nameplate lists code letters that range from A to V, they indicate the type of rotor bars used when the rotor was made. Different types of bars are used to make motors with different operating characteristics. The type of rotor bars largely determines the maximum starting current of the motor. NEC Table 430.7(B) lists the different code letters and gives the locked-rotor kilovolt-amperes per horsepower. The starting current can be determined by multiplying the kilovolt-ampere rating by the horsepower rating and then dividing by the applied voltage.
The second method of determining locked rotor current is to use Tables 430.251(A) and (B) if the motor nameplate lists NEMA design codes. Table 430.251(A) lists the locked rotor currents for single-phase motors and Table 430.251(B) lists the locked rotor currents for poly-phase motors.

How Do You Determine Locked Rotor Current

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How Do You Determine Locked Rotor Current

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