only 7SJ623, 7SJ624, 7SJ625, 7SJ626 and 7SJ64
If a busbar voltage is used for input V
4
(for voltage protection or synchrocheck) for the devices 7SJ623,
7SJ624, 7SJ625, 7SJ626 or 7SJ64 and the assigned VT mcb is connected to the device, the following function
must also be checked:
If the VT mcb is open the annunciation
>FAIL: BUS VT
“ON” appears, if it is closed the annunciation
>FAIL: BUS VT
“OFF” is displayed.
Switch off the protected power line.
Test for High Impedance Protection
Polarity of Transformers
When the device is used for high-impedance protection, the current at Ι
N
or Ι
Ns
is equivalent to the fault
current in the protected object. It is essential in this case that all current transformers feeding the resistor
whose current is measured at Ι
N(S)
have the same polarity. The test currents used for this are through currents.
Each CT must be included in a measurement. The current at Ι
N(S)
may never exceed half the pickup value of the
single-phase time overcurrent protection.
Testing the Reverse Interlocking Scheme
(only if used)
Testing reverse interlocking is available if at least one of the binary inputs available is configured for this
purpose (e.g. presetting of binary input BI1
>BLOCK 50-2
and
>BLOCK 50N-2
to open circuit system). Tests
can be performed with phase currents or ground current. For ground current the corresponding ground
current settings apply.
Please note that the blocking function can either be configured for the pickup current connected (open circuit
system) or the pickup current missing (closed circuit system). For open circuit system the following tests are to
be proceeded:
The feeder protection relays of all associated feeders must be in operation. At the beginning no auxiliary
voltage is fed to the reverse interlocking system.
A test current higher than the pickup values of 50-2 PICKUP and 50-1 PICKUP or 51 PICKUP is set. As a
result of the missing blocking signal, the protection function trips after (short) time delay 50-2 DELAY.
CAUTION
Tests with currents that exceed more than 4 times the nominal device current
cause an overload of the input circuits.
²
Perform test only for a short time (see Technical Data, Section 4.1 General Device Data). Afterwards
the device has to cool off !
The direct voltage for reverse interlocking is now switched on to the line. The precedent test is repeated, the
result will be the same.
Subsequently, at each of the protection devices of the feeders, a pickup is simulated. Meanwhile, another fault
is simulated for the protection function of the infeed, as described before. Tripping is performed within time
50-1 DELAY (longer time period) (with definite time overcurrent protection) or according to characteristic
(with inverse time overcurrent protection).
These tests also check the proper functioning of the wiring for reverse interlocking.
3.3.7
3.3.8
Mounting and Commissioning
3.3 Commissioning
SIPROTEC 4, 7SJ62/64, Manual 425
C53000-G1140-C207-8, Edition 08.2016
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