( )
=
D × - ³ ×
æ ö
æ ö
ç ÷
ç ÷
ç ÷
è ø
è ø
å
1
P
n
j
i j
t C A td
Pickupn
EQUATION1644 V1 EN (Equation 198)
where:
j = 1 is the first protection execution cycle when a fault has been
detected, that is, when
EQUATION1646 V1 EN
Dt is the time interval between two consecutive executions of the
protection algorithm,
n is the number of the execution of the algorithm when the trip time
equation is fulfilled, that is, when a trip is given and
i (j) is the fault current at time j
For inverse time operation, the inverse time characteristic is selectable. Both the IEC
and ANSI/IEEE standardized inverse time characteristics are supported.
For the IEC curves there is also a setting of the minimum time-lag of operation, see
figure
567.
Section 22 1MRK505222-UUS C
Inverse time characteristics
1184
Technical reference manual
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