ABBDistributed busbar protection REB500 including line and transformer protection Product Guide

protection, transformer protection etc.

After the delay of the first timer has expired, a 

tripping command can be applied to a second

tripping coil on the circuit-breaker and a 

remote tripping signal transmitted to the station at the opposite end of the line.

This first timer operates in a stand-alone 

mode in the bay unit.

If the fault still persists at the end of the second time delay, the breaker failure function 

uses the busbar replica to trip all the other 

feeders supplying the same section of busbar 

via their bay units.

A remote tripping signal can be configured in 

the software to be transmitted after the first or 

second timer.

Phase-segregated measurements in each bay 

unit cope with evolving faults.

End fault protection

In order to protect the “dead zone” between 

an open circuit-breaker and the associated 

CTs, a signal derived from the breaker position and the close command is applied.

The end fault protection is enabled a certain 

time after the circuit-breaker has been opened. In the event of a short circuit in the dead 

zone the nearest circuit-breakers are tripped.

This function is performed in a stand-alone 

mode in the bay unit.

Overcurrent function

A definite time overcurrent back-up protection 

scheme can be integrated in each bay unit. 

(The operation of the function, if para-meterized, may start the local breaker failure protection scheme).

This function is performed in a stand-alone 

mode in the bay unit.

Current release criteria

The current release criteria is only performed 

in the bay unit. It is effective for a busbar protection trip and for an intertripping signal 

(including end fault and breaker failure) and 

prevents those feeders from being tripped that 

are conducting currents lower than the setting 

of the current release criteria.

Voltage release criteria

The voltage criterion is measured in the bay 

unit. The function can be configured as 

release criterion per zone through internal 

linking in the central unit. This necessitates 

the existence of one set of voltage transformers per zone in one of the bay units. Tripping

Distributed busbar protection REB500

including line and transformer protection

is only possible if the voltage falls short of 

(U<) or exceeds (U0>) the set value.

Additionally this release criterion can be configured for each feeder (voltage transformers 

must be installed). For details see Table 22.

Check zone criterion

The check zone algorithm can be used as a 

release criterion for the zone-discriminating 

low-impedance busbar protection system. It is 

based on a stabilized differential current measurement, which only acquires the feeder currents of the complete busbar. The isolator / 

breaker positions are not relevant for this criterion.

Neutral current detection I0 

Earth fault currents in impedance-grounded 

systems may be too low for the stabilized differential current and phase comparison functions to detect. A function for detecting the 

neutral current is therefore also available, but 

only for single phase-to-earth faults.

Pole discrepancy

A pole discrepancy protection algorithm 

supervises that all three poles of a circuitbreakers open within a given time. 

This function monitors the discrepancy between the three-phase currents of the circuitbreaker.

When it picks up, the function does not send 

an intertripping signal to the central unit, but, if 

configured, it starts the local breaker failure 

protection (BFP logic 3).

This function is also performed in a standalone mode in the bay unit.

Event recording

The events are recorded in each bay unit. A 

time stamp with a resolution of 1ms is attached to every binary event. Events are divided 

into the three following groups:

• system events

• protection events

• test events

The events are stored locally in the bay unit or 

in the central unit.

Disturbance recording

This function registers the currents and the 

binary inputs and outputs in each bay. Voltages can also be optionally registered (see 

Table 14).

A disturbance record can be triggered by 

either the leading or lagging edges of all 

binary signals or by events generated by the 

internal protection algorithms. Up to 10 general-purpose binary inputs may be configured 

to enable external signals to trigger a disturbance record. In addition, there is a binary 

input in the central and the bay unit for starting 

the disturbance recorders of all bay units.

The number of analog channels that can be 

recorded, the sampling rate and the recording 

period are given in Table 14. A lower sampling 

rate enables a longer period to be recorded.

The total recording period can be divided into 

a maximum of 15 recording intervals per bay 

unit.

Each bay unit can record a maximum of 32 

binary signals, 12 of which can be configured 

as trigger signals.

The function can be configured to record the 

pre-disturbance and post-disturbance states 

of the signals.

The user can also determine whether the recorded data is retained or overwritten by the