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Multilin  MIB

High Impedance Busbar Differential Relay


The MIB, a member of the M II family of economical and highly functional digital protection relays, is a microprocessor based relay that provides three phase high impedance differential protection for Substation Bus-bars of any voltage level.

Use the MIB also to protect electrical machines like transformers, generators or motors against restricted earth faults.

Basic protection functions features include a high impedance differential protection unit with a tripping time of 1 1/2 cycles. Stability against external faults is guaranteed thanks to the use of a stabilizing resistor. The unit includes a set of MOVs (Metal Oxide Varistors) provided to clamp the secondary peak voltage below 2kV during fault conditions.

The relay includes open CT detection which provides an alarm when it detects sustained current unbalance conditions, issuing a warning signal and blocking the operation of the unit.

Features & benefits :

  • Configurable logic, curves, I/Os and LEDs

  • Flash memory for field upgrades

  • Two settings groups

  • Drawout case

  • Password protection for local operation

  • Automatic display of last fault information

  • DC power supply

  • Access via front panel keypad or communication links

  • EnerVista software for setting & monitoring

  • Isolated front RS232 serial port

  • RS485 rear port



  • Differential protection for single and split busbar arrangements.

  • Zero sequence differential (restricted ground fault) protection for reactors, generators, large motors, and other power apparatus


Protection & Control 

  • High impedance differential protection

  • Open CT detection

  • Lockout logic

  • Configurable I/O

  • 6 outputs, four configurable, plus trip and alarm


Monitoring & Metering

  • 24-event record

  • Analog/digital oscillography

  • Per phase differential current metering

  • Monitoring of the last 5 trips information from the display


User Interface

  • 2x16 character LCD display

  • 6 LED indicators, 4 configurable in function and color

  • EnerVista software for setting and monitoring

  • Front RS232 and rear RS485 ports using ModBus® RTU protocol up to 19,200 bps


MIB Brochure

MIB Manual

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