ABB Motor Protection Relays and Controls
Motor Protection Relays and Controls
Motor protection is used to prevent damage to the electrical motor, such as internal faults in the motor. Also external conditions when connecting to the power grid or during use have to be detected and abnormal conditions must be prevented. Additionally, the protection relay prevents the disturbance to spread back into the grid.
Motor protection schemes have several protection functions to consider:
- Motor horsepower rating and type
- Supply characteristics such as voltage, phases, method of grounding, and available short-circuit current
- Vibration, torque, and other mechanical limits
- Nature of the process
- Environment of motor, associated switching device
- Hot and cold permissible locked-rotor time and permissible accelerating time
- Time versus current curve when starting the motor
- Frequency of starting
The protection relays provide main protection for synchronous and asynchronous motors. They can be used for circuit-breaker and contactor-controlled motors in a variety of drive applications, such as, motor drives for pumps, fans, compressors, mills and crushers.