Pulsar TC-10B, Руководство пользователя

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Page 2–4 October 2003
TC–10B System Manual
Technologies, Inc.
2.1.3 Single Phase-
Comparison
Blocking, Current
Only
In the current only system, the
TC–10B is used with two overcur-
rent fault detectors (FD
l
and FD
2
).
FD
1
, the carrier start unit, is set
more sensitively than FD
2
and
permits the local square wave
signal to key the “ON/OFF” carrier
transmitter. FD
2
, set with a higher
pickup than FD
1
, is used to arm the
system for tripping. For transmis-
sion lines less than 100 miles long,
the FD
2
pickup is set at 125 percent
of FD
1
. For lines longer than 100
miles, the FD
2
pickup is set at 200
percent of FD
1
. On a three-terminal
line, FD
2
is set at 250% of FD
1
,
provided the line length between
any two breakers is less than 100
miles. Phase-Comparison cannot
occur until FD
2
operates. The
purpose of the two fault detectors is
to coordinate the comparison of the
local and remote square waves with
the keying of the carrier square
wave. The carrier must be started
before the comparison is allowed
to ensure that the remote square
wave has been received.
The basic operation of the system is
shown in Figure 2-3. FD
1
and FD
2
at
both terminals operate for an
internal fault (F
I
). The square wave
inputs to the AND from the local
currents are essentially in phase
with those transmitted via the
channel from the remote terminal.
The local square wave turns the
carrier “ON” and “OFF” to provide
the square wave receiver output for
the remote terminal.
A flip flop is energized if the inputs
to the AND continue for 4ms,
providing a continuous trip output
supervised by FD
2
operation. The 4ms correspond to a phase
angle difference of 90°, on a 60-Hz base, between the currents at
the two terminals. The currents at the two ends of the line may
be out of phase by up to 90° and still trip. This is a blocking
system, since the receipt of a signal from the channel prevents
tripping. The carrier signal, therefore, does not have to be trans-
mitted through the internal fault. No received signal puts a “1”
on the AND input. With the remote terminals open, this system
provides sensitive instantaneous overcurrent protection for the
entire line. As is characteristic of blocking systems, the channel
is not required for tripping on internal faults.
For an external fault, such as F
E
in Figure 2-3, blocking is essen-
tially continuous, since the remote wave input to the AND is
out-of-phase with the local square wave. The secondary ct
currents are essentially out-of-phase for an external fault. The
currents can, however, be in-phase by up to 90
°
on a 60-Hz base
and still block.
Protected Line
G H
1 2
Transmitter
Receiver
Channel
Fault Detecting Logic
(Figure 2–2)
Fault Detecting Logic
(Figure 2–2)
Receiver
Output
Receiver
Output
Local
Input Local
Input
Comparison Circuit
Basic Logic
Arming Arming
Internal Fault (F
I
)
(at Terminal G*)
External Fault (F
E
)
(at Terminal G*)
Local Input
to AND
Receiver
Output
Receiver Input
to AND
AND Output
Trip Output
* Equivalent operation and same trip output at Station H.
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1 1
1
1
1
4
0
Comparison Circuit
Basic Logic
4
0
Trip Breaker 1 Trip Breaker 2
Transmitter
Receiver
F
I
& F
E
F
E
F
E
F
I F
I
AND AND
Figure 2–3.
Single Phase Comparison Blocking, Current Only Operation.