2–20
M-3520 Instruction Book
46 Negative Sequence Overcurrent
The Negative Sequence Overcurrent function pro-
vides protection against possible damage due to
unbalanced current conditions.
This function has a definite time element and an
inverse time element. The definite time pickup value
and operating time are normally associated with an
alarm function. The inverse time element is usually
associated with a trip function.
The inverse time function can be selected as one of
the eight curve families: definite, inverse, very
inverse, extremely inverse, and four IEC curves.
The operator selects the pickup and time dial
settings.
This protection must
not operate for system faults
that will be cleared by feeder/line relaying. This
requires consideration of feeder line protection,
bus differential, and breaker failure backup
protections.
46DT PICKUP
________ Amps
46DT DELAY
________ Cycles
46IT PICKUP
________ Amps
46IT CURVE
DEF in vinv einv
46IT TIME DIAL
________
Negative sequence overcurrent
pickup establishes the nega-
tive sequence overcurrent
level above which the function
timer will start.
This setting is the operating time of the function.
Negative sequence overcurrent
pickup establishes the nega-
tive sequence overcurrent
level above which the function
timer will start.
This setting selects, one of eight family of curves, as shown
in Appendix D, Figures D-1 through D-8.
The appropriate curve in the selected family of curves is
chosen here.
If this function is enabled, the following settings are applicable:
Summary of Contents for M-3520
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