Siemens siprotec 7SD5 User Manual page 509

infeed. In case of release (the NC contacts of the outgoing devices are connected in
series) the tests have to be reinterpreted respectively.
A fault is simulated within zone Z1 and overreaching zone Z1B. As a result of the
missing blocking signal, the distance protection trips after time delay T1B (slightly de-
layed).
The direct voltage for reverse interlocking is now switched to the line. The precedent
test is repeated, the result will be the same.
At each of the protection devices of the outgoing circuits, a pickup is simulated. Mean-
while, another short-circuit is simulated as described before for the distance protection
of the infeed. Now, the distance protection trips after time T1, which has a longer set-
ting.
These tests also check the proper functioning of the transmission path. All other tests
which are described in this Section can be passed over. However, please observe the
last margin heading „Important for All Schemes"!
Checking with Per- Prerequisites: Teleprot. Dist. is configured in address 121 to one of the compar-
ison schemes using blocking signal, i.e. POTT or Dir.Comp.Pickup or
missive Schemes
UNBLOCKING. Furthermore, is switched in address 2101 FCT Telep. Dis. ON. Nat-
urally, the corresponding send and receive signals must also be assigned to the cor-
responding binary output and input. For the echo function, the echo signal must be al-
located separately to the transmit output!
Detailed information on the function of permissive scheme is available in Section 2.7.
A simple check of the signal transmission path from one line end is possible via the
echo circuit if these release techniques are used. The echo function must be activated
at both line ends, i.e. address 2501 FCT Weak Infeed = ECHO only; with the
setting ECHO and TRIP at the remote end of the check a tripping command may
result!
A short-circuit is simulated outside Z1, with POTT or UNBLOCKING inside Z1B, with
Dir.Comp.Pickup somewhere in forward direction. This may be done with second-
ary injection test equipment. As the device at the opposite line end does not pick up,
the echo function comes into effect there, and consequently a trip command is issued
at the line end being tested.
If no trip command appears, the signal transmission path must be checked again, es-
pecially also the assignment of the echo signals to the transmit outputs.
In case of a phase-segregated transmission the above-mentioned checks are carried
out for each phase. The correct phase allocation is also to be checked.
This test must be performed at both line ends, in the case of three terminal lines at
each end for each signal transmission path.
The functioning of the echo delay time and the derivation of the circuit breaker switch-
ing status should also be tested at this time (the functioning of the protection at the
opposite line end is tested):
The circuit breaker on the protected feeder must be opened, as must be the circuit
breaker at the opposite line end. As described above, a fault is again simulated. A
receive signal impulse delayed by somewhat more than twice the signal transmission
time appears via the echo function at the opposite line end, and the device issues a
trip command.
The circuit breaker at the opposite line end is now closed (while the isolators remain
open). After simulation of the same fault, the receive and trip command appear again.
7SD5 Manual
C53000-G1176-C169-1
3.3 Commissioning
509