Micom P721, Техническое руководство

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P72x/EN AP/C21 Application Guide
Page 26/52 MiCOM P721/P723
Logic output relay 5 = 1
tEqu.C = 0000000000000100
Logic output relay 6 = 1
As shown in FIGURE 24, the buswire shorting is asserted when either the protection
trips or the buswire supervision element is asserted.
[95A] tSUP
OR
Buswire Shorting
[95B] tSUP
[95C] tSUP
[87] tDIFF
OR
[95] tSUP
P4501ENa
FIGURE 24: P723 – THREE PHASE APPLICATIONS - BUSWIRE SHORTING LOGIC
As shown in FIGURE 25, the high impedance path must be shorted under three possible
situations: when the protection trips, when the protection is out of service and when the
buswire supervision element is asserted. This is required to avoid unnecessary overheating
of the stabilizing resistor and varistor.
The high impedance path must be shorted when the protection trips. This can be done using
normally open contacts from the 86 relay as shown in FIGURE 25.
In the P723, the watchdog normally open contact may be used to energize an auxiliary relay
as shown in FIGURE 25. The normally closed contacts from the auxiliary relay are used to
short the high impedance path when the P723 is out of service. An additional contact from
the auxiliary relay is required to give an alarm to the SCADA system when the P723 is out of
service.