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ElecToolsHQ

Locked Rotor Current Calculator

Calculate a motor's locked rotor (starting) current from full load current and its locked rotor multiplier (LRC = FLC × Multiplier).

The motor's locked rotor current multiplier, from its nameplate or manufacturer data.

Formula

LRC = FLC × Multiplier

LRC
Locked rotor current, in amps
FLC
Full load current, in amps
Multiplier
The motor's locked rotor current multiplier

What this calculator does

Calculates the inrush current a motor draws when starting, from its full load current and locked rotor multiplier.

Use cases

  • Size starting equipment and short-circuit protection for motor inrush
  • Check whether a breaker can handle a motor's starting current
  • Compare locked rotor current across motors with different multipliers

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