-ETHOD OF OPERATION
3*
6
# ' #
2ESET THRESHOLD
R
|
5
|
53#
0ICK UP THRESHOLD
4HRESHOLD FOR
START UP CRITERION
5
N
5
RMS
T
T
)
RMS
T
)
N
5 RESET
5 3#
5
3# )
T
T
4RIP
COMMAND
#,/3%
COMMAND
0ICK UP
5
$ROP OFF
5
4 5
4RIP
4 3#
2ECLOSURE
LOCKED
0ICK UP
&IGURE 4YPICAL FAULT SEQUENCE WITH VOLTAGE TRANSFORMERS INSTALLED AT THE BUS BAR SIDE
4HE GENERAL CURRENT CRITERION ## MENTIONED UNDER
APPLIES EQUALLY TO BOTH UNDERVOLTAGE STAGES
7ITH AN ACTIVATED CURRENT CRITERION THE PROTECTION
PICKS UP ONLY WHEN TOGETHER WITH THE UNDERVOLTAGE
CONDITION ALSO THE RELEASE CONDITION OF THE CURRENT
CRITERION ## IS FULFILLED 4HIS ALSO MEANS THAT FOR UN
DERVOLTAGE WITHOUT RELEASE FROM THE CURRENT CRITERION
THE PROTECTION PICK UP RESETS
)N ORDER TO AVOID MALOPERATION IN CASE OF A SECOND
ARY VOLTAGE FAILURE EG BY OPERATION OF THE VOLTAGE
TRANSFORMER MINIATURE CIRCUIT BREAKER THE PROTEC
TION CAN BE BLOCKED VIA A BINARY INPUT FOR BOTH UNDER
VOLTAGE STAGES TOGETHER OR SEPARATELY FOR 5 AND
5 VIA TWO BINARY INPUTS 7HEN BLOCKING BE
COMES EFFECTIVE DURING A PICK UP CONDITION THE
PICK UP RESETS AS WELL AS THE STARTED DELAY TIMES
ARE RESET TOO
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