Enter the Locked Rotor Amps (LRA) and the voltage into the calculator to determine the running current in amps. This calculator helps in converting LRA to Amps for electrical systems.

LRA to Amps Formula

The following formula is used to convert Locked Rotor Amps (LRA) to Amps (A). 

A = frac{LRA}{Voltage}

Variables:

  • A is the running current in amps (A)
  • LRA is the Locked Rotor Amps (LRA)
  • Voltage is the voltage applied to the electrical system (volts)

To convert LRA to Amps, divide the Locked Rotor Amps by the voltage applied to the electrical system.

What is Locked Rotor Amps (LRA)?

Locked Rotor Amps (LRA) is the current drawn by a motor when the rotor is not turning. It occurs at the moment power is applied to the motor and is significantly higher than the running or full-load amps. LRA is an important specification for starting electric motors and is used to size circuit breakers and fuses to handle the initial inrush current safely.

How to Calculate Amps from LRA?

The following steps outline how to calculate the running current in Amps from LRA.

  1. First, determine the Locked Rotor Amps (LRA) of the motor.
  2. Next, determine the voltage applied to the electrical system.
  3. Use the formula from above: A = LRA / Voltage.
  4. Finally, calculate the running current in Amps (A).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Locked Rotor Amps (LRA) = 50 A

Voltage = 240 V