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I.L. 40-386.3
should be set to "Reverse Dir" and Zone3Ø (Z3P) , Z3G should be set to 100% of
the line impedance.
f.
The test function selection provides the capability to simulate the TK switch function
for keying action via OR-18 and AND-35 without the operation of pilot relay units, and
to simulate the RS switch function for receiving of a trip or unblocking frequency sig-
nal action without the operation from the remote transmitter.
g. Programmable Reclosing Initiation (Figure 2-19)
The basic programmable RI application is as described in Section 3.4.14. However, on
pilot systems, to activate the RI2 on any 3-pole high-speed trip, the external pilot en-
ables switch should be ON, and the Pilot (PLT) and Zone1RI (Z1RI) should be set to
YES. The operation will occur via the logic AND-89, AND-84 and OR-84A as shown in
Figure 2-19.
2.5.1.2
Permissive Underreach Transfer Trip
The basic operating concepts of a PUTT scheme are:
(1) Pilot relays (Pilot Ø and PLTG) are set to overreach. The pilot channel is a frequen-
cy-shift type device, and the transmitter frequency should be different at each
terminal; its signal may be passed through metallic wire or microwave.
(2) Channel is normally operated with a guard frequency, the channel frequency will
be shifted from guard to trip when the Zone1 reach relay (Z1Ø/Zone1G) operates,
and pilot trip is performed when the pilot relay (Pilot Ø and/or PLTG) operates, to-
gether with the receiving of a carrier trip signal from the remote end.
PUTT includes the following logic: the functional display (SystType) should be set to
PUTT position.
a. Pilot Tripping Logic
The Pilot Tripping Logic for the PUTT scheme is exactly the same as for the POTT
scheme (Figures 2-20, 2-21).
b. Carrier Keying Logic
(1) Forward fault keying (Figure 2-23)
For a forward end Zone fault, the PUTT scheme will not key except when the internal fault
is within Zone1. This means that the PUTT scheme keys only on Zone1 faults. Keying flows
via AND-46, OR-18 and AND-35.
(2) Signal continuation (Figure 2-22)
Same as for POTT scheme.
The TBM logic is not required because the carrier keying units are set underreach.
2-16
†
Channel Simulation
(10/94)
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