UBZ-302-01 universal asynchronous induction motor protection unit is designed for protection of dual-speed (double-coil) asynchronous induction motors, for continuous monitoring of the mains voltage parameters and phase/line RMS currents, as well as for the motor insulation resistance test.
UBZ unit provides for protection of dual-speed (double-coil) asynchronous induction electric motors of 5 to 50A rated current with use of integrated current transformers.
The UBZ unit provides for electric motor protection in the following cases:
- when the mains voltage is of poor quality (unallowable voltage surges, phase loss and phase/line voltage imbalance, incorrect phase sequence and phase “coincidence”);
- when mechanical overloads (symmetrical phase/line current overload) occur;
- when reverse sequence of the current threshold (current imbalance) occurs;
- when start delay or rotor obstruction;
- when the insulation level between the fixed coil and frame is abnormally low (startup check);
- when stator winding ground-to-fault takes place during operation – ground leak current protection is activated;
- when motor heat overload takes place.
Selection of the protection parameters is defined by the user in course of the device programming. For each separate type of protection, the unit allows to prohibit or allow automatic load reset (AR).
It is equipped with complete set of protections implemented in UBZ-301 version. It additionally provides protection against long lasting start and rotor blockage as well as motor winding overheating monitoring with use of temperature sensors.