What is motor overload protection?
KB’s AC drives contain Motor Overload Protection (I²t) with RMS Current Limit (CL). The I²t function provides overload protection and prevents motor burnout. KB’s AC drives are UL approved as an electronic overload protector for motors.
With I²t, if the motor is overloaded to 120% of the motor nameplate rating, the I²t timer will start, triggering the drive to trip in 30 minutes. As the motor continues to experience an increase in load, the time it takes the drive to trip decreases. Finally, if the motor is overloaded to 160%, the drive will trip in six seconds. The CL factory settings are for a maximum overload of 160%, limiting the motor current and torque.
Some drive manufacturers do not have the current limit feature. During an extreme overload the I²t time is very short, which will cause an undesirable nuisance trip.