Areva MiCOM P441, Technical Manual

Page: 263 / 636

Application Notes P44x/EN AP/E33
MiCOM P441/P442 & P444 Page 89/220
P0549ENa
&
&
DEF Fwd
Reversal Guard
Any Pole Dead
Any DIST Start
DEF Timer Block
DEF V>
UNB CR DEF
&
0
150 ms
IN Rev>
t_delay
DEF CS
DEF Trip
T
0
0
Tp
IN Fwd>
DEF Rev
DEF V>
IN Rev>
>1
FIGURE 56 - SHARED CHANNEL – BLOCKING SCHEME
Send logic: DEF Reverse
Trip logic: IN> Forward, plus Channel NOT Received, with small set delay.
IN> Fwd (A)
P0550ENa
ZL
A B
IN> Fwd (B)
IN> Rev (A)
IN> Rev (B)
FIGURE 57 - THE DEF BLOCKING SCHEME
Trip Trip
Signal
Send IN>
Reverse Signal
Send IN>
Reverse
IN >
IN>1
t
0
IN>2
t
0
t
0
&
>1
>1
t
0
IN>1
t
0
IN>2
t
0
&
IN>
Forward
Forward
P0551ENa
Protection A Protection B
FIGURE 58 - LOGIC DIAGRAM FOR THE DEF BLOCKING SCHEME
The scheme has the same features/requirements as the corresponding distance scheme
and provides sensitive protection for high resistance earth faults.
Where “t” is shown in the diagram this signifies the time delay associated with an element.
To allow time for a blocking signal to arrive, a short time delay on aided tripping must be
used. The recommended Time Delay setting = max. signalling channel operating time +
14ms.