You will need
  • Technical documentation on the motor.
Identify the type of motor. It could be the motor constant currentor three-phase alternating current. Calculate the nominal current of the motor DC currentin amperes, using the formula: IH=1000PH/(ηHUH), and the nominal current of the motor three-phase currentand using the formula: IH=1000PH/(UHcosφH√ηH), where:Rn is the nominal engine power, kW;UH — the motor rated voltage, V;ηH is the nominal efficiency of the engine;cos Fn is the nominal power factor of the motor. Data on nominal power, nominal voltage, efficiency and power factor take from the technical documentation of the motor.
Calculate the value of the starting currentin amperes after the calculation of its nominal value. To calculate use the formula:IN=IH*KP, where IH is the nominal value of currenta, and KP - the rate constant currentand its nominal value. Review the technical documentation on the motor, it must be specified the multiplicity is constant currentand its nominal value (CP). Multiply this number by the resulting value of the nominal currentand and get the value of starting currentin amperes. Calculate for each motor in the chain.
Pick up a circuit breaker to protect the line of inclusion depending on the magnitude of inrush currentas all the motors in the circuit. Please know that circuit breakers can be type of off, C and D. the Switches with the feature of disconnecting type suitable for lighting networks of General purpose, with the feature disable-type are used for disconnection of lighting circuits and systems with moderate starting current ofAMI (motors and transformers). For circuits with an active-inductive load, and also for protection of electric motors with large starting currentAMI typically used to use switches with characteristics of type D. Identifying the type of switch, adjust depending on the magnitude of the inrush current.