Siemens Siprotec 7VK61 Manual page 33

Rated frequency
The nominal frequency of the system is set in address 230 Rated Frequency. The presetting according to
the ordering code (MLFB) only needs to be changed if the device is applied in a region different to the one in-
dicated when ordering. You can set 50 Hz or 60 Hz.
System Starpoint
For the 7VK61, the settings for the system starpoint are only relevant for the operation of the „Fuse Failure Mon-
itor" (see also 2.7.1). Accordingly, set for address 207 SystemStarpoint = Solid Earthed, Peterson-
Coil or Isolated. For („low-resistant") earthed systems set Solid Earthed.
Phase Rotation
Use address 235 PHASE SEQ. to change the default setting (L1 L2 L3 for clockwise rotation) if your power
system has a permanent anti-clockwise phase sequence (L1 L3 L2).
Closing time of the circuit breaker
The circuit breaker closing time T-CB close at address 239 is required if the device is to close also under
asynchronous system conditions, no matter whether for manual closing, for automatic reclosing after three-pole
tripping, or both. The device will then calculate the time for the close command such that the voltages are
phase-synchronous the instant the breaker poles make contact.
Trip command duration
In address 240 the minimum trip command duration TMin TRIP CMD is set. It applies to all protective and
control functions which may issue a trip command. It also determines the duration of the trip pulse when a circuit
breaker test is initiated via the device. This parameter can only be altered using DIGSI under Additional Set-
tings.
In address 241 the maximum close command duration TMax CLOSE CMD is set. It applies to all close com-
mands issued by the device. It also determines the length of the close command pulse when a circuit breaker
test cycle is issued via the device. It must be long enough to ensure that the circuit breaker has securely closed.
There is no risk in setting this time too long, as the close command will in any event be terminated following a
new trip command from a protective function. This parameter can only be altered using DIGSI under Additional
Settings.
Circuit breaker test
7VK61 allows a circuit breaker test during operation by means of a tripping and a closing command entered on
the front panel or using DIGSI. The duration of the trip command is set as explained above. Address 242 T-
CBtest-dead determines the duration from the end of the trip command until the start of the close command
for this test. It should not be less than 0.1 s.
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
Functions
2.1 General
33