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S&C Instruction Sheet 681-530
Definite-Time Phase Protection (Negative Sequence)
Definite-Time Protection Elements (Element #1 and Element #2)
Select to enable
or disable protection settings for the selected way. Definite Time selection is available
if a IEC, IEEE, or Vista coordination phase TCC curve is selected or if no TCC curve is
specified for phase protection.
Definite-Time Phase Protection
settings will trip the
fault interrupter if the selected current exceeds the setting value for the specified time
setting.
The
Definite Time Phase Protection #1
element must be enabled for the
Definite
Time Phase Protection #2
element to be enabled. When programming both the
Defi-
nite Time #1
element and the
Definite Time #2
element, the
Definite Time #2
element
must be set at a higher current and a faster speed than the
Definite Time #1
element or
an error will occur. The
Definite Time #1
and
Definite Time #2
elements also must be
greater than the
Low-Current Cutoff
setting and the minimum trip current. The time
must be faster than the time-overcurrent protection curve.
Definite-Time Current, A
– This is the current at which the
Definite Time
element
picks up. (Definite-Time Element 1 or Element 2.)
Definite-Time Time, s
– This is the time delay at which the
Definite Time
Current
element picks up. (Definite-Time Element 1 or Element 2.)
Reset Time Parameters (Negative Sequence)
Reset Type
– The Reset parameter is a definite time reset method and the
Type
field is
always set to
Timed
mode.
Reset Time, s
– Enter the time delay for the definite time reset, if desired. Accumulated
value will reset to zero after reset time has elapsed.
(Sensitive Earth Fault) Protection Element
– Select to enable or disable protection
settings for the selected way. The
Sensitive Earth Fault
element trips the fault
interrupter when the computed residual of the three-phase currents exceeds the pickup
value for the time value set by the
Inverse Curve
or
Definite-Time
settings.
Curve Family
– Select the TCC curve family: IEC, IEEE, or Vista Coordination desired.
For more details on the curve families, see the “Overcurrent Control Settings” section
on page 56 for the curve families available. The TCC curves available can also be found
in S&C Information Bulletin 680-211, “Time-Current Characteristic Curves.”
Inverse Segment
– Select the desired segment from the drop-down list of curves.
Ampere Rating
– Select the ampere rating from the drop down menu for Vista
Coordination TCC curves. The IEEE and IEC curves do not use the ampere rating field.
Minimum-Trip Current, A
– This is the current at which the inverse curve begins timing.
Sensitive Earth Fault
Overcurrent Protection Setting Definitions
