Functional Description

REB670 Busbar Protection – Key Features and Benefits

The REB670 supports disconnector position monitoring, enabling reliable operation in double-busbar substations. This feature helps maintain the stability of the busbar differential protection scheme even if an incorrect busbar disconnector status is indicated in any feeder bay.

A flexible, software-based Dynamic Zone Selection function allows the protection system to be quickly adapted to a wide variety of substation configurations, including:

Single busbar systems (with or without a transfer bus)
Double busbar systems (with or without a transfer bus)
Breaker-and-a-half arrangements
Double busbar, double breaker configurations
Ring busbar substations
Other complex busbar layouts

The Dynamic Zone Selection function provides several important advantages:

Automatically assigns current transformer (CT) measurements to the correct differential protection zone based on the actual substation topology.
Dynamically merges two differential protection zones during operating conditions such as load transfer.
Ensures selective busbar differential protection by tripping only the circuit breakers associated with the faulted busbar zone.
Correctly distributes backup trip commands from the integrated or external circuit breaker failure protection to all required surrounding circuit breakers.
Simplifies the integration of bus-section and bus-coupler (tie-breaker) bays equipped with either one or two sets of CTs.
Continuously supervises the status of disconnectors and circuit breakers to improve operational reliability.

The advanced Zone Selection logic, combined with optional end-fault protection and circuit breaker failure protection, minimizes operating time while maintaining excellent selectivity. These functions provide comprehensive protection for faults occurring in blind spots or end zones located between the feeder CT and the circuit breaker, ensuring maximum fault coverage for feeder bays, bus-section bays, and bus-coupler bays.

For enhanced system reliability, the REB670 can be equipped with dedicated circuit breaker failure protection for each CT input, providing secure local backup protection for every circuit breaker within the substation.

The device can also include four-stage, non-directional overcurrent protection for every CT input. This optional feature delivers effective remote backup protection for connected feeders as well as remote substations.

In most substations, a single busbar protection IED is installed for each protected busbar. However, some utilities prefer two fully independent busbar protection IEDs for each protection zone to achieve higher system redundancy. The REB670 is designed to support both single-IED and dual-redundant protection architectures, providing the flexibility required for different utility protection philosophies.

Recommended other models：