ABBDistributed busbar protection REB500 including line and transformer protection Product Guide

Three-phase voltage plausibility

This function is used for checking the sum and 

the phase sequence of the three-phase voltages.

Additional

features

Self-supervision 

All the system functions are continuously 

monitored to ensure the maximum reliability 

and availability of the protection. In the event 

of a failure, incorrect response or inconsistency, the corresponding action is taken to 

establish a safe status, an alarm is given and 

an event is registered for subsequent diagnostic analysis.

Important items of hardware (e.g. auxiliary 

supplies, A/D converters and main and program memories) are subjected to various 

tests when the system is switched on and also 

during operation. A watchdog continuously 

monitors the integrity of the software functions 

and the exchange of data via the process bus 

is also continuously supervised.

The processing of tripping commands is one 

of the most important functions from the reliability and dependability point of view. Accordingly, every output channel comprises two 

redundant commands, which have to be 

enabled at regular intervals by a watchdog. If 

the watchdog condition is not satisfied, the 

channels are blocked.

Extension of the system

The system functions are determined by software, configured using the software configuration tool.

The system can be completely engineered in 

advance to correspond to the final state of the 

station. The software modules for new bays or 

features can be activated using the HMI500 

when the primary plant is installed or the features are needed.

Additional system functions, e.g. breaker failure, end fault protection or bay level 

back-up / Main 2 functions can be easily activated at any time without extra hardware.

Resetting the trip commands/-signals

The following resetting modes can be selected for each binary output (tripping or signal 

outputs):

• Latches until manually reset

• Resets automatically after a delay

Inspection/maintenance

A binary input is provided that excludes a bay 

unit from evaluation by the protection system. 

It is used while performing maintenance 

respectively inspection activities on the primary equipment.

Redundant power supplies (Option)

Two power supply modules can be fitted in a 

redundant arrangement, e.g. to facilitate 

maintenance of station batteries. This is an 

option for the central unit as well as for the 

bay unit.

Time synchronization

The absolute time accuracy with respect to an 

external time reference depends on the 

method of synchronization used:

• no external time synchronization:

accuracy approx. 1 min. per month

• periodic time telegram with minute pulse 

(radio or satellite clock or station control 

system): accuracy typically ±10 ms

• periodic time telegram as above with second pulse: accuracy typically ±1 ms

• a direct connection of a GPS or DCF77 to 

the central unit is possible: accuracy typically ±1 ms

• Furthermore, the time synchronization can 

be done, if available, via the interbay bus 

IEC103, LON or SNTP (in case IEC61850-

8-1 is used)

The system time may also be synchronized by 

a minute pulse applied to a binary input on the 

central unit.

Distributed busbar protection REB500

including line and transformer protection

Page 17 

Requirements Optical fiber cables

A distributed busbar protection layout requires optical fiber cables and connectors with 

the following characteristics:

• 2 optical fiber cores per bay unit

• glass fibers with gradient index 

• diameter of core and sheath 62.5, 

respectively 125 m

• maximum permissible attenuation 5 dB

• FST connector (for 62.5 m optical fibers)

• rodent protected and longitudinally waterproof if in cable ducts 

Isolator auxiliary contact

Auxiliary contacts on the isolators are connected to binary inputs on the bay units and 

control the status of the busbar replica in the 

numerical busbar protection.

One potentially-free N/O and N/C contact are 

required on each isolator. The N/O contact 

signals that the isolator is “CLOSED” and the 

N/C contact that the isolator is “OPEN”. During the closing movement, the N/O contact 

must close before the isolator main contact 

gap reaches its flashover point.

Conversely, during the opening movement, 

the N/O contact must not open before the isolator main contact gap exceeds its flashover 

point.

If this is not the case, i.e. the contact signals 

‘no longer closed’ beforehand, then the N/C 

contact may not signal “OPEN” before the 

flashover point has been exceeded.

Distributed busbar protection REB500

including line and transformer protection

Circuit-breaker replica

When the circuit-breaker replica is read in the 

feeder or the bus-tie breaker, the circuitbreaker CLOSE command must also be connected. 

Main current transformer

The algorithms and stabilization features used 

make the busbar protection largely insensitive 

to CT saturation phenomena. Main CTs types 

TPS (B.S. class x), TPX, TPY, 5P.. or 10P.. are