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Mounting and Commissioning
3.3 Commissioning
Voltage Transformer Miniature Circuit Breaker (VT mcb)
The VT mcb of the feeder (if used) must be opened. The measured voltages in the operational measured
values appear with a value close to zero (small measured voltages are of no consequence).
Check in the spontaneous annunciations that the VT mcb trip was entered (annunciation
"ON" in the spontaneous annunciations). Beforehand it has to be assured that the position of the VT mcb is
connected to the device via a binary input.
Close the VT mcb again: The above messages appear under the spontaneous messages as "OFF", i.e.
>FAIL:FEEDER VT "OFF".
If one of the events does not appear, the connection and allocation of these signals must be checked.
If the
ON -state and OFF –state are swapped, the contact type (H–active or L–active) must be checked and
remedied.
Test for High Impedance Protection
3.3.8
Polarity of Transformers
When using the high impedance protection, the current corresponds to the fault current in the protection
object. It is essential in this case that all current transformers feeding the resistor whose current is measured
at Ι
have the same polarity. Through-flowing currents are used for that. Each of the current transformers has
Ns
to be included in a measurement. The current at Ι
phase overcurrent protection.
Testing the Reverse Interlocking Scheme
3.3.9
(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
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
Test with currents above 20 A continuous current
Cause an overload of the input circuits.
Perform the test only for a short time (see Technical Data, Section
²
wards, 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, a pickup is simulated at each of the protection devices of the feeders. Meanwhile, another
shortcircuit is simulated for the protection function of the infeed as described before. Tripping is now effected
in the (longer set) time 50-1 DELAY (for definite time overcurrent protection).
These tests also check the proper functioning of the wiring for reverse interlocking.
488
must never exceed half the pickup value of the single-
Ns
>BLOCK 50-2 and >BLOCK 50N-2 to open circuit system). Tests
>FAIL:FEEDER VT
4.1 General Device
Data). After-
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
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