Zone 3 Trip - ABB REL300 Instruction Manual

The single-phase ground distance units may respond to a φφG fault. The output of the Z2G unit
plus the operation of the φφ selection will trip the Z2P via OR-157, T2P 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 Zone 2 timers
(phase and ground units) are independent, as follows:
• T2P (Zone 2 phase)
• T2G (Zone 2 ground)
The range of the timers is as follows:
• T2P and T2G (0.1 to 2.99 seconds or Block)
Either or both Zone 2 phase and Zone 2 ground function(s) can be disabled by setting Z2P and/
or Z2G to the BLK position.
3.3.3

Zone 3 Trip

For Zone 3 phase faults, the Z3P (forward or reverse looking, depending on the Z3FR setting)
unit will identify the faults, plus the IM output will operate the Zone 3 phase timer T3P. AND-6
output plus the T3P timer output satisfy AND-20 (as shown in Figure 3-7, page 3-32). The AND-
20 output provides time delay trip signal (TDT) via OR-3. Signal TDT picks up OR-4 (Figure 3-
5, page 3-30) and operates the trip relay. The tripping and targeting are similar to Zone 1 trip,
except for the Zone 3 phase time delay trip indicator (Z3P).
For Zone 3 single-phase-to-ground faults, Z3G identifies the fault and operates. This, plus the
operation of the IOM, satisfies AND-7; the TDT signal then trips via OR-3 with Zone 3 ground
time delay trip indicator Z3G. The TDT signal can be connected to the reclosing block logic. For
security, the Z3G unit is also supervised by the signal of FDOG when it is set for forward looking
(or by the signal of RDOG when it is set for reverse looking) via logic OR-171B, AND-171C or
AND 171D (as shown in Figure 3-7).
A similar operation for φφG faults (shown in Zone 2), is applied to Zone 3, through OR-170, T3P
and AND-20 gates.
The settings for Zone 3 timers (phase and ground units) are independent, as follows:
• T3P (Zone 3 phase)
• T3G (Zone 3 ground)
The range of the timers is as follows:
• T3P and T3G (0.1 to 9.99 seconds or Block)
Either or both Zone 3 phase and Zone 3 ground function(s) can be disabled by setting Z3P and/
or Z3G to the BLK position.
I.L. 40-385.7
3-5