ABB RELION REX640 Technical Manual page 830

Protection and control

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Table of Contents

Protection functions

FAULT_DIR gives the detected direction of the fault during fault situations, that is,

when the START output is active.

The ability of a protection relay to provide direction information for faults is

referred to as its directional security. It is extremely important for the directional

protection function to identify the direction of the fault relative to the location of

the protection relay. The fault direction can be either downstream (forward fault) or

upstream of the protection relay (backward fault).

Different directional elements are used to determine the fault direction. One such

element is the negative-sequence voltage. As directional element, the negative-

sequence voltage can identify the direction of all unbalance faults. One of the

advantages of using negative-sequence elements is that the negative-sequence

component is insensitive to zero-sequence mutual coupling. The negative sequence

is also used where the source is not strong enough because with such a source the

value of the negative sequence near the protection relay has higher magnitude.

DNSPDOC Input signals

Table 746: DNSPDOC Input signals

DNSPDOC Output signals

Table 747: DNSPDOC Output signals

DNSPDOC Settings

Table 748: DNSPDOC Group settings (Basic)

Values (Range)

Directional mode

1=Non-directional

Table continues on the next page

Three-phase currents

Residual current

Three-phase voltages

Block signal for acti-

vating the blocking

1MRS759142 F

Directional mode

Technical Manual