Numerical Protection Relays

Product Details:

The UBZ-304 Numeric electric motor protection device is designed for protection of asynchronous LT motors having power of 2.5 to 315 kW (5A - 630A), with use of external standard current transformers having output current of 5 amperes (secondary), works in power mains with isolated neural or with solidly grounded neutral terminals.

The device provides continuous monitoring of the mains voltage parameters and RMS phase/line currents of the three-phase electric equipment of 380V-415V 50Hz, as well as for the motor insulation resistance test. More than 90 parameters can be programmed/customised depending on application & usage with variable trip delay and auto-reset delays. Four line full function backlit LCD display provides all information and eases programming from front panel. Built In RS-232 & RS-485 Modbus communication for DCS/ SCADA integration, realtime monitoring, programming and remote control. Device comes with free PC software for realtime monitoring & programming. Universally accepted flush mounted 96 x 96 x 78.3mm overall dimensions.

The UBZ provides electric motor protection in the following cases:

• when the mains voltage is of poor quality – voltage fluctuations & surges, phase loss (single phasing), wrong phase sequence and phase "coincidence" (short circuits) and phase/line voltage imbalance (asymmetry).
• when mechanical overloads/symmetrical phase/line current overloads occur (over current).
• when reverse sequence of the current threshold occurs.
• when phase current imbalance (without overload) occurs that is induced by the insulation fault inside the motor and/or the lead cable (current imbalance factor compared to voltage imbalance factor based on negative sequence).
• when motor torque is lost ("dry run" for pumps). The unit provides protection based on the minimum start and/or operating current.
• when start delay or rotor locking/locked rotor condition occurs.
• when insulation level between the fixed coil (stator) and frame is abnormally low (insulation resistance test before motor start).
• when stator winding ground fault takes place during operation, the UBZ unit activates ground leakage current protection.
• when motor thermal overload takes place (calculated in terms of current sqare x resistance x time).
• when winding overheating occurs (winding temperature measured by integrated temperature sensors, or frame temperature measured by external temperature sensors).
• when over & under frequency fault occurs.

For each type of protection, it is possible to permit and prohibit the load automatic reset. The unit provides for electric equipment protection by means of a magnetic starter (contactor) coil control.

The unit determines load currents when the load relay is open with the open load and programmable relays in the star-delta mode). In this case, the unit shall indicate the fault of an external contactor, which is starting the motor until unit deactivation.

Communication:

• control and parameters transfer via RS-485 interface according to MODBUS protocol
• control and parameters transfer via RS-232 interface

Documentation for this device

Additional Information:

• Item Code: UBZ-304
• Port of Dispatch: New Delhi