Trip Circuit Supervision For Busbar Protection; Different Busbar Arrangements; General; Single Busbar Arrangements - ABB REB670 Applications Manual

1MRK 505 337-UUS -
6.1.3.18
6.1.4
6.1.4.1
6.1.4.2
Application manual

Trip circuit supervision for busbar protection

Trip circuit supervision is mostly required to supervise the trip circuit from the individual
bay IED panel to the circuit breaker. It can be arranged also for the tripping circuits from
the busbar protection.
However, it can be stated that the circuit from a busbar protection trip relay located in the
busbar protection panel is not so essential to supervise as busbar faults are very rare
compared to faults in bays, especially on overhead power lines. Also it is normally a small
risk for faults in the tripping circuit and if there is a fault it affects only one bay and all other
bays are thus correctly tripped meaning that the fault current disappears or is limited to a
low value.

Different busbar arrangements

General

Busbar differential protection application principles for typical busbar arrangements are
shown and described in this chapter.

Single busbar arrangements

The simplest form of busbar protection is a one-zone protection for single busbar
configuration, as shown in figure 53. When different CT ratios exist in the bays
compensation is done by setting the CT ratio individually for each bay.
The only requirement for busbar protection is that the protection scheme must have one
differential zone. For any internal fault all circuit breakers must be tripped, which will
cause loss of supply to all loads connected to the station.
ZA
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ANSI06000087 V1 EN
Figure 53: Example of single busbar section with six feeder bays
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Section 6
Differential protection
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