A tool designed to estimate the electrical current drawn by a three-phase electric motor. It typically utilizes the motor’s horsepower rating, voltage, and efficiency to provide an approximation of the amperage. For example, given a 10 horsepower motor operating at 460 volts with 90% efficiency, the calculation yields an estimated full-load amperage.
Accurately estimating motor current is crucial for selecting appropriate circuit protection devices (fuses and circuit breakers), ensuring proper wire sizing to prevent overheating and voltage drop, and determining the correct size of motor starters and other control equipment. Historically, relying on nameplate data was sufficient, but calculators offer a convenient means of estimation during design phases or when nameplate information is unavailable, enhancing safety and system performance.