Alstom MiCOM P546 - 1.23.10 Aided DEF ground fault scheme - permissive overreach (Distance option only)

P54x/EN OP/La4 Operation
(OP) 5-70 MiCOM P543, P544, P545 & P546
OP
1
DDB: CTx (498,514)
DDB: CRx Int (494,508)
1
DDB: COS/LGS Alarm (492,506)
DDB: Aided Trip En (501,517)
SET: Reversal
Guard
t
RGD
P1585ENc
Figure 43 Blocking 2 (Distance option only)
The relative merits of Blocking 1 and Blocking 2 are discussed in the Application Notes.
1.23.10 Aided DEF ground fault scheme - permissive overreach (Distance option only)
Figure 44 shows the ele
ment reaches, and Figure 45 the simplified scheme logic. The
signaling channel is keyed from operation of the forward IN> DEF element of the relay. If the
remote relay has also detected a forward fault, then it will operate with no additional delay
upon receipt of this signal.
Send logic: IN> Forward pickup
Permissive trip logic: IN> Forward plus Channel Received
P1306ENa
B
A
ZL
IN> Fwd (A)
IN> Fwd (B)
Figure 44 The DEF permissive scheme (Distance option only)
The scheme has the same features/requirements as the corresponding distance scheme
and provides sensitive protection for high resistance earth faults.