The UBZ-302-01 universal asynchronous motor protection unit is designed to protect two-speed (two-winding) motors, continuously monitor the mains voltage, current values of phase/line currents, and check the insulation resistance of the motors.
UBZ provides protection for asynchronous two-speed (two-winding) motors with a rated current from 5 to 50A when using built-in current transformers.

UBZ provides protection for electric motors in the following cases:

• low-quality mains voltage (unacceptable voltage surges, open and skewed phases, phase alternation and phase sticking)
• mechanical overloads (symmetrical overload in phase/line currents)
• exceeding the reverse sequence current threshold (current skew)
• delayed motor start or rotor blockage
• unacceptably low level of insulation between the stator and the motor housing (check before switching on)
• stator winding earth fault during operation - earth leakage current protection
• motor thermal overload

The set of protection parameters is determined by the user by programming the device.

For each type of protection, it is possible to prohibit or enable automatic reclosing of the load.

It has a complete set of protections implemented in UBZ-301. Additionally, it provides protection against delayed start and rotor blocking, and monitors motor windings overheating using temperature sensors.