MiCOM Busbar Applications

MiCOM Busbar Differential Applications

P721 / P723

High Impedance Differential Protection Relays

MiCOM P72x high impedance differential protection series provides high impedance differential protection for generators, reactors, motor and busbar applications.

Models available:

  • MiCOM P721

  • MiCOM P723

MiCOM P72x apart from offering the same application benefits as traditional high impedance electromechanical protection schemes, it combines the added benefits of numerical technology to provide advanced communications, event records, fault records, disturbance records and ancillary protection features.

Combined with the MiCOM P79x, a standalone metrosil and resistor unit, it provides simplified scheme engineering for single or three-phase differential applications.

P741 / P742 / P743 / P746

Numerical Busbar Protection Relay Scheme (Centralized)

Easergy™ MiCOM P746 numerical busbar protection provides centralized complete protection for all voltages level up to extra high voltage busbar configurations.

Models available:

  • MiCOM P746

Simple configuration for centralized architecture. The Easergy MiCOM P746 differential busbar protection provides a centralized one box or three boxes architecture and is very simple to use.

It does not need to be deeply engineered and supports easy operation and maintenance of the busbar.

Numerical Busbar Protection Relay Scheme (Distributed)

The Easergy MiCOM P740 numerical busbar protection scheme provides scalable and complete protection for all voltage levels, from low to extra or ultra high-voltage busbar configurations.

Models available:

  • MiCOM 741

  • MiCOM 742

  • MiCOM 743

Easergy MiCOM P740 is one of the fastest and complete in its class, providing secure and sensitive protection for all types of voltage busbar configurations. It is easily adapted to any configuration and can operate with different types of CT.

Functions available for the different models of the Busbar protection MiCOM range of relays


Protection Function






Ground fault



Phase overcurrent



Circuit breaker failure




Check Zones



Phase segregated differential

8 zones


4 zones


Sensitive ground fault differential

8 zones



Current transformer supervision


Trip circuit supervision


Voltage transformer supervision



Phase comparison



CT saturation detection



CT supervision


Typical Catalog Numbers

Catalog Number


Standard — High Impedance Busbar Differential

P723 with external stabilizing resistor P793


Series 20 - High Impedance bus differential Protection, P723 (24-250Vdc & 48-240Vac), 1/5A CT inputs, 5In/8Out (24-250 Vdc, 24-240Vac), RS485, Modbus


External stabilizing resistor, 20kJ

Advanced — Low impedance Busbar Differential
(1 or 3 box mode)


Series 40 - Low Impedance bus differential (7 sets of CT's) Protection, P746 (48-110Vdc), 1/5A CT inputs, 16In/16Out (user configurable voltage thresholds), 3xRJ-45, IEC61850, DNP3

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