ABB REL301 Instruction Manual page 25

I.L. 40-386.3
A two-out-of-three "leading phase blocking" logic is included for solving the overreach
problem of the single-phase ground distance units, which may respond to a two
phase-to-ground (ØØG) fault.
The high-speed trip (HST) signal also is connected to the reclosing initiation logic.
Both Zone1 phase and Zone1 ground function(s) can be disabled by setting the
Zone1Ø and/or Zone1G to the (OUT) setting choice. Zone1 trip can be delayed with
the setting T1 Timer. The delay time is up to 5 cycles. Normally, this timer is set to Ø.
2.3.2 Zone2 Trip
For Zone2 phase faults, the Zone2Ø unit will see the faults and operate the Zone2
phase timer. The timer limit denoted T2P in Figure 2-6 can be selected to be either a
definite time T2Ø time or an inverse time (CO type) characteristic (settings T2ØCV,
T2Ø PkUp and TØ TC). Zone2 Ø output plus the T2P timer output satisfy AND-18 as
shown in Figure 2-6.
Similar operation occurs for Zone2 single-phase-to-ground faults. The Zone2G unit
sees the fault and operates. This, plus the operation of the IOM, FDOG and T2G (Def-
inite Time T2G Time or inverse time (CO) characteristic) satisfy AND-19, and provide
the TDT signal via OR-3 with Zone2 ground time delay trip indicator.
The single-phase ground distance units may respond to a ØØG fault. The output of
the Zone2G unit plus the operation of the ØØ selection will trip the Zone2 Ø via OR-
157, T2Ø time and AND-18. Leading phase blocking is unnecessary for an overreach
Zone device.
The TDT signal can be connected to the reclosing block logic. The settings for Zone2
timers (phase and ground units) are independent, as follows:
For Zone2 phase and ground:
All phase and ground settings are independent of one another.
If T2ø type and/or T2G Type was selected as Definite Time:
2-4
Table 3:
T2ø Type and T2G Blocked
Type Definite Time
Torque Control (may be
Inverse Time)
Table 4:
T2ø Time and 0.10 to 2.99 seconds
T2G Time 0.10 to 2.99 seconds
(10/94)