Pulsar TCF-10B, Системное руководство, Страница: 36 / 249

this remote signal is received for
1,000 ms (1 sec) or longer, the
carrier receiver logic interprets this
as an open breaker and allows the
local end to trip whenever the local
relays detect a fault.
2.1.2 Permissive
Overreaching
Transfer Trip
Systems
Overreaching transfer trip systems
require a channel signal to trip, and
are used with a frequency-shift
audio tone, modulated on a
communication channel (e.g.,
public or private telephone lines).
These systems are generally not
used with power line carriers.
There are, however, successful
applications of power-line carrier
on POTT schemes where parallel
lines allow for cross-coupling of
the carrier signal.
2.1.3 Permissive and
Non-Permissive
Underreaching
Transfer Trip
Systems
For overreaching systems, the
directional phase and ground trip
fault detectors (P) must be set to
overlap within the transmission
line and not overreach any
terminals (see Figure 2-3).
That is, at least one trip fault
detector (P) must operate for all
internal faults, and none should
operate for any external fault. In
practice, distance relays are
normally required for both ground
faults and phase faults, although
directional instantaneous ground-
overcurrent relays might meet
these requirements in some cases.
Page 2–4 December 1996
TCF–10B System Manual
Technologies, Inc.
Breaker 1 Trip Fault Detectors (P
1
) Breaker 1 Permissive Fault Detectors (FD
1
)
Breaker 2 Trip Fault Detectors (P
2
)
Breaker 2 Trip Fault Detectors (P
2
)
Protected Line
G H
F
I
F
E
1 2
Contact Logic (per Terminal)
P
FD Trip
Solid State Logic (per Terminal)
Channel
except Power Line Carrier
Audio Tone
Receiver f
2
Audio Tone
Receiver f
1
Audio Tone
Transmitter f
1
Audio Tone
Transmitter f
2
RR
Audio
Tone
Receiver
RR
Trip
Coil
52a
FD P
Key Audio Tone Transmitter
to Remote Station
Key Audio Tone Transmitter
to Remote Station
Key Audio Tone Transmitter
to Remote Station
Audio Tone
Receiver
Omit and Bypass
for Non-Permissive
Schemes
AND OR
Permissive Schemes
Non-Permissive Schemes
P
Trip
Audio Tone
Recovery
OR
Figure 2–3. Basic Logic Diagrams for
Underreaching Transfer Trip Systems.
Though it is the least complex, the non-permissive system is rarely
used because of the high potential for false outputs from the
channel, which would cause incorrect tripping. If a non-permissive
system is used, the channel considerations should be as described
later for direct trip systems. The system is made permissive by the
additional set of phase and ground overreaching fault detectors
(FD), which must operate for all internal faults (see Figure 2-3).
Operation of the underreaching transfer trip scheme shown in
Figure 2-3 is described in Table 2-2 for external and internal faults.