Overview

ACRs are sometimes installed in network configurations where power flow could be in either direction through the switchgear. Directional Protection can be used when the ACR is required to coordinate with different protection devices depending on which side of the switchgear the fault is detected that is whether the power flow during a fault is forward or reverse. When power flows from Source to Load, the power flow is deemed to be forward. Reverse power flows from Load to Source. The Source and Load sides of the switchgear are configurable through the Power Direction setting.

The Power Direction setting can be found on the WSOS Measurements page or on the operator interface.

Directional Protection is an optional protection feature that uses separate protection groups to determine pickup thresholds and protection timing depending on which side of the switchgear the fault has been detected.

NOTE: Because the direction of the fault needs to be determined before the correct protection settings can be applied, there is a minimum delay of approximately 20 ms that applies to all types of directional overcurrent protection that is Phase, Earth, SEF, and NPS.

When Directional Protection is On, there are always two protection groups active. One group is for forward faults and the other is for reverse faults. If the controller is configured for ten protection groups, five pairs will be available as shown in the table below.

Table 50 Directional Protection Active Protection Group Pairs

Forward	Reverse
Group A	Group B
Group C	Group D
Group E	Group F
Group G	Group H
Group I	Group J

Which pair becomes active when Directional Protection is turned On depends on which group was previously active. If Group A was active, Groups A and B will become active. If Group D was active, Groups C and D will become active.

The active protection groups can be changed to another pair once Directional Protection is On.

WSOS will display a warning message to advise which protection groups will become active when Directional Protection is turned On.

NOTE: if an odd number of protection groups have been configured, not all will be available for Directional Protection for example, if five groups have been configured only two pairs (A+B and C+D) can be selected.

Directional Protection can only be turned on from the WSOS Feature Selection page. It can’t be turned on from the Options pages on the setVUE O.I. or the Feature Selection pages on the flexVUE O.I.