Zone 1 Extension; Rel300 Non-Pilot Features; 3-Zone Distance Phase And Ground Relay With; Directional Or Non-Directional Inverse Time - ABB REL300 Instruction Manual

I.L. 40-385.7
3.3.4

Zone 1 Extension

This scheme provides a higher speed operation on end zone faults without the application of a
pilot channel.
If the REL300 functional display "STYP" is set on Z1E position, the Z1P/Z1G unit will provide
two outputs: one is overreach which is set at 1.25 x Z1 reach by the microprocessor, and one
is the normal Z1 reach. A single shot instantaneous reclosing device must be used when ap-
plying this scheme. The targets Z1P/Z1G will indicate either Z1 trip and/or Z1E trip operations.
The other functions (e.g., Z2T, Z3T, ac trouble monitoring, overcurrent supervision, IT, CIF, un-
equal-pole closing load pickup control, load-loss acceleration trip, etc.) would remain the same
as in the basic scheme (3ZNP).
For a remote internal fault (refer to Figure 3-8, page 3-33), either Z1P or Z1G will see the fault
since they are set to overreach. High speed trip will be performed via the normal Z1T path (Fig-
ure 3-5), i.e., AND-2 (or AND-3), OR-2. HST signal operates the instantaneous reclosing
scheme. The breaker recloses and stays closed if the fault is automatically cleared.
Target Z1P and/or Z1G will be displayed. Once the breaker trip circuit carries current, it oper-
ates the logic OR-5 (not shown), produces output signal TRSL, and satisfies logic AND-26 for
5000 ms (Figure 3-8). The output signal of AND-26 will trigger the Z1P/Z1G reach circuit, con-
stricting their reaches back to the normal Zone 1 for 5000 ms. During the reach constricting pe-
riods, if the breaker is reclosed on a Zone 1 permanent fault, it will retrip again. If the breaker
is reclosed on an end-zone permanent fault, the normal Z2T will take place.
For a remote external fault, either Z1P or Z1G will see the fault since they are set to overreach.
High speed trip will be performed. HST signal operates the instantaneous reclosing scheme.
The breaker recloses and stays closed if the fault has been isolated by the adjacent line break-
er. However, if the adjacent line breaker fails to trip, the normal remote back up will take place.
NOTE: The reaches of Z1E are based on the Zone 1 settings multiplied by a factor of 1.25
(e.g., 1.25 x Z1P and 1.25 x Z1G).
3.4

REL300 NON-PILOT FEATURES

The following features are standard with the Non-Pilot REL300:
3.4.1 3-Zone Distance Phase and Ground Relay with Reversible Zone 3 Phase and Ground
There are four impedance units per zone: one phase-to-phase unit and three phase-to-ground
units. Zone 3 can be set to forward or reverse for carrier keying or back-up tripping. For a pilot
system, Z3FR has to be set to reverse (REV) for correct application.
3.4.2 Directional or Non-Directional Inverse Time Overcurrent Ground Backup Unit
The overcurrent ground backup (GB) unit is to supplement the distance ground protection on
high resistance ground faults. It provides an inverse time characteristic which is similar to the
conventional CO characteristics (see Figure 2-1 thru 2-7). The time curves can be selected by
the GBCV Setting. The time dial is set by the "GTC" value. The unit can be selected as direc-
tional by using the "GDIR" (YES) setting and the pickup value by GBPU. The directional GB
3-6