3 Mounting and Commissioning
426
7SA522 Manual
C53000-G1176-C155-3
Checking for
Blocking Scheme
Requirements: 7HOHSURW() is configured in address to one of the compari-
son schemes using blocking signal, i.e. %/2&.,1*. Furthermore, )&77HOHS()
is switched 21 at address . Naturally, the corresponding send and receive
signals must also be assigned to the corresponding binary output and input.
For more details about the function of the blocking scheme refer to Subsection 2.8. In
the case of the blocking scheme, communication between the line ends is necessary.
An earth fault in the reverse direction is simulated at the transmitting line end. Subse-
quently, a fault at the receiving end in the direction of the line is simulated. This can be
achieved with a set of secondary injection test equipment at each end of the line. As
long as the transmitting end is transmitting, no trip signal must appear at the receiving
line end, except in a higher time set as backup stage. After the simulated fault at the
transmitting line end has been cleared, the receiving line end remains blocked for the
duration of the transmit prolongation time of the transmitting line end (6HQG
3URORQJ, address ). If applicable, the transient blocking time of the receiving
line end (7U%ON%ORFN7LPH, address ) appears additionally if a finite delay time
7U%ON:DLW7LPH (address ) has been set and exceeded.
This test must be executed at both line ends, in the case of three terminal lines at each
line end and for each transmission path. Finally, please observe the last margin
heading “Important for All Schemes”!
Important for all
Schemes
If the distance protection was switched off for the signal transmission tests, it may be
switched on now. If setting parameters were changed for the test (e.g. mode of the
echo function or timers for unambiguous observation of sequences), these must now
be re-set to the prescribed values.
3.3.14 Check of the Signal Transmission for Breaker Failure Protection and/or End
Fault Protection
If the transfer trip command for breaker failure protection or stub fault protection is to
be transmitted to the remote end, this transmission must also be checked.
To check the transmission the breaker failure protection function is initiated by a test
current (secondary) with the circuit breaker in the open position. Make sure that the
correct circuit breaker reaction takes place at the remote end.
Each transmission path must be checked on lines with more than two ends.
3.3.15 Check of the Signal Transmission for Internal and External Remote Tripping
The 7SA522 provides the possibility to transmit a remote trip signal to the opposite line
end if a signal transmission path is available for this purpose. This remote trip signal
may be derived from both an internally generated trip signal as well as from any signal
coming from an external protection or control device.
If an internal signal is used, the initiation of the transmitter must be checked. If the
signal transmission path is the same and has already been checked as part of the pre-
vious sections, it need not be checked again here. Otherwise the initiating event is
simulated and the response of the circuit breaker at the opposite line end is verified.
In the case of the distance protection, the permissive underreach scheme may be
used to trip the remote line end. In this case, the procedure is the same as for permis-
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