ABBDistributed busbar protection REB500 including line and transformer protection Product Guide

be protected. An integrated tripping scheme 

allows to save external logics as well as wiring.

The capacity is sufficient for up to 60 feeders 

(bay units) and a total of 32 busbar zones.

The numerical busbar protection REB500 

detects all phase and earth faults in solidly 

grounded and resistive-grounded power systems and phase faults in ungrounded systems 

and systems with Petersen coils.

The main CTs supplying the currents to the 

busbar protection have to fulfil only modest 

performance requirements (see page 18). The 

protection operates discriminatively for all 

faults inside the zone of protection and 

remains reliably stable for all faults outside the 

zone of protection.

REB500sys

The REB500sys is foreseen in MV, HV and 

EHV substations with nominal frequencies of 

16.7, 50 Hz or 60 Hz to protect the busbars 

and their feeders. The bay protection functions included in REB500sys are used as 

Main 2 / Group 1 - or back-up protection.

The system REB500sys is foreseen for all single or double busbar configurations (Line variants L-V1 to L-V7 and Transformer variant TV1 to T-V4). In 1½ breaker configurations, 

variant L-V5 can be used for the bay level 

functions autoreclosure and synchrocheck. 

The capacity is sufficient for up to 60 feeders 

(bay units) and a total of 32 busbar zones.

The REB500sys detects all bus faults in solidly and low resistive-grounded power systems, all kind of phase faults in ungrounded 

and compensated power systems as well as 

feeder faults in solidly, low resistive-grounded, 

compensated and ungrounded power systems.

The protection operates selectively for all 

faults inside the zone of protection and 

remains reliably stable for all faults outside the 

zone of protection.

REB500sys is perfectly suited for retrofit concepts and stepwise upgrades. The bay unit is 

used as a stand-alone unit for bay protection 

functions (e.g. line protection, autoreclosure 

and synchrocheck or 2- and 3 winding transformer protection or autonomous T-zone protection). The central unit can be added at a 

later stage for full busbar and breaker failure 

protection functionality.

Distributed busbar protection REB500

including line and transformer protection

Depending on the network voltage level and 

the protection philosophy the following protection concepts are generally applied:

• Two main protection schemes per bay 

and one busbar protection.

With REB500sys the protection concept 

can be simplified. Due to the higher integration of functionality one of the main protection equipment can be eliminated.

• One main protection and one back-up 

protection scheme per bay, no busbar 

protection.

With REB500sys a higher availability of the 

energy delivery can be reached, due to the 

implementation of busbar and breaker failure protection schemes where it hasn't 

been possible in the past because of economical reasons.

Nine standard options are defined for Main 2/ 

Group 1 or back-up bay level functions:

Line protection

- Line variant 1 (L-V1)

directional, non-directional overcurrent and 

directional earth fault protection

- Line variant 2 (L-V2)

as line variant L-V1 plus distance prot.

- Line variant 3 (L-V3)

as line variant L-V2 plus autoreclosure

- Line variant 4 (L-V4)

as line variant L-V3 plus synchrocheck

- Line variant 5 (L-V5)

as line variant L-V1 plus autoreclosure and 

synchrocheck.

- Line variant 6 (L-V6) for 16.7 Hz

non-directional overcurrent, distance protection, autoreclosure.

- Line variant 7 (L-V7) for 16.7 Hz

as line variant L-V6 plus directional earth 

fault protection for grounded systems

Transformer protection

- Transformer variant 1 (T-V1)

2- or 3 winding transformer differential protection, thermal overload, current functions; 

applicable also as autonomous T-zone protection.

- Transformer variant 2 (T-V2)

2-winding transformer differential protection, thermal overload, current functions, 

overfluxing protection, neutral overcurrent 

(EF).

- Transformer variant 3 (T-V3)

Distance protection for transformer back-up 

or 2-winding transformer differential protection, thermal overload, current functions, 

voltage functions, frequency functions, 

power function, overfluxing protection.

- Transformer variant 4 (T-V4)

Transformer oriented functions/ back-up 

functions -> thermal overload, current functions, voltage functions, frequency functions, power function, overfluxing protection.

Distributed busbar protection REB500

including line and transformer protection

Mode of 

installation

There are three versions of installing the numerical busbar protection REB500 and the numerical station protection REB500sys:

Distributed installation

In this case, the bay units (see Fig. 24) are 

installed in casings or cubicles in the individual switchgear bays distributed around the 

station and are connected to the central processing unit by optical fiber cables. The central processing unit is normally in a centrally 

located cubicle or in the central relay room.