The Novatek UBZ-302 is a microprocessor-based digital device that provides protection for 3-phase motors. No external power supply is required as the unit uses the same power supply as the motor. It has been designed to work in 3-phase electric circuits with or without an isolated neutral connection, allowing operation in both in 3 and 4 wire circuits.
The UBZ-302 has 3 built-in current measurement transformers through which the motor power supply wires are looped for continuous current monitoring. In addition, it continuously monitors the power supply voltage, phase/line currents and the leakage resistance of the motor coils.
The UBZ-302 can protect electric motors with rated power from 2.5 to 30kW using its built-in current transformers. With the use of externally connected current transformers (not included) it can protect motors with a rated power of up to 315kW.
Protects from voltage surges, fluctuations, phase loss, wrong phase sequence, phase imbalance and phase coincidence
Mechanical overloads (symmetrical overload in phase/line currents)
Exceeding the threshold for reverse current sequence
Non-symmetry of the phase currents
Minimum starting current protects against loss of drive torque (dry stroke for pumps)
Minimal operation current protects against long lasting motor start or jammed rotor
Checks insulation between the stator and motor case before motor start
Earth leakage protection of stator coils during the motor operation
