Checking The Instrument Transformer Connections Of One Line End - Siemens siprotec 7SD5 User Manual

Line differential protection with distance protection
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3 Mounting and Commissioning
In particular with multiple busbars the trip distribution logic for the surrounding circuit
breakers must be checked. Here check for every busbar section that all circuit break-
ers which are connected to the same busbar section as the feeder circuit breaker
under observation are tripped, and no other breakers.
Tripping of the
If the trip command of the circuit breaker failure protection must also trip the circuit
Remote End
breaker at the remote end of the feeder under observation, the transmission channel
for this remote trip must also be checked. This is done together with transmission of
other signals according to Sections „Testing of the Teleprotection Scheme with ..."
further below.
Termination of the
All temporary measures taken for testing must be undone, e.g. especially switching
Checks
states, interrupted trip commands, changes to setting values or individually switched
off protection functions.
3.3.7

Checking the Instrument Transformer Connections of One Line End

Should secondary test equipment be connected to the device, it is to be removed or,
if applying, test switches should be in normal operation position.
Note
It must be taken into consideration that tripping can occur even at the opposite ends
of the protected object, if connections were made wrong.
Before energizing the object to be protected at any end, short-circuit protection must
be ensured at least at the feeding ends. If a separate back-up protection (e.g. overcur-
rent protection) is available, this has to be put into operation and switched to alert first.
Voltage and Phase
If the device has been connected to voltage transformers, these connections are
Sequence Check
checked using primary values. For devices without voltage transformer connection the
rest of this margin heading may be omitted.
The voltage transformer connections are individually tested at either end of the object
to be protected. At the other end(s) the circuit breaker(s) remain open first.
492
7SD5 Manual
C53000-G1176-C169-1

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