Motor Specifications – Voltage,Ampere and Frequency

These parameters are important to clarify our application design from voltage value,phases,full load ampere, overload setting and frequency setting if using Variable Speed Drive.

As an electrician,we must fully understand what is mean by voltage, ampere and frequency to ensure our application safe and working properly.

Ok…let we start our discussion and explanation about Voltage, Ampere and Frequency on Electric Motor Nameplate.


What is Rated Voltage?For simple understanding, rated voltage is manufacturer design for suitable operated voltage value with optimal performance.We can refer the motor voltage and phases on the nameplate also can decide either voltage/phases is available in our installation or not.Every country have different value of voltage.Please make sure your motor are followed standard country voltage.

Incoming voltage or Line voltage normally will fluctuate due to several factors.From this issue,electric motor manufacture are designed their motor with 10% tolerance for voltage above and below rated value.Example if motor voltage value on nameplate is 460V should be expected to running properly between 414 Volt to 506 Volt.

To make some motor to be more variety voltage,manufacturer also design electric motor with dual voltage value.We just change the motor connection termination ( Star or Delta ) depend on voltage that we need to operate that motor.


How this value outcome?Manufacture perform laboratory tested to get the Full Load ampere value when reached maximum frequency, full load torque and horsepower with rated voltage.

The nameplate FLA value is important when we need to design and sizing for motor cable, overload setting and types of motor starter that can serve and protect this motor properly.

From this value also we can perform troubleshooting to check either motor is running in good condition or not.It’s simple, clamp your motor to get running ampere and compare with FLA value on nameplate.


Rated frequency is value of hertz (HZ) that designed by manufacturer specific to the motor.Normally in Canada or USA, the rated frequency is 60HZ but in others country it will be 50 HZ or 60 HZ.

Frequency value are important when you plan to use Variable Speed Drive (VSD) to control the motor operation.In VSD parameter setup, this value must be enter correctly by followed nameplate to avoid any damage.


  1. erhurhe victor says

    do you know any material that can stop electromagnetic flux?

  2. erhurhe victor says

    what is the speed of a transformer?

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