34 S&C Instruction Sheet 695-535
Low-Current Cutoff (Negative Sequence)
Low-Current Cutoff – Select to enable or disable the low-current cutoff. It is not possible
to enable the low-current cutoff setting if the associated time overcurrent protection
element is disabled. The low-current cutoff setting will not change automatically when a
different curve family is selected. This value will only change when modied by the user.
Low-Current Cutoff, A – This is the current at which the TCC curve begins timing.
This value must be equal to or greater than the lowest pickup value of the inverse curve.
Definite-Time Phase Protection (Negative Sequence)
Denite-Time Protection Elements (Element #1 and Element #2) Select to enable
or disable protection settings for the selected way. Denite 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
specied time setting.
The Denite Time Phase Protection #1 element must be enabled for the Denite Time
Phase Protection #2 element to be enabled. When programming both the Denite Time
#1 element and the Denite Time #2 element, the Denite Time #2 element must be
set at a higher current and a faster speed than the Denite Time #1 element or an error
will occur. The Denite Time #1 and Denite 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.
Denite-Time Current, A – This is the current at which the Denite Time element
picks up. (Denite-Time Element 1 or Element 2.)
Denite-Time Current, s – This is the time delay at which the Denite Time element
picks up. (Denite-Time Element 1 or Element 2.)
Reset Time Parameters (Negative Sequence)
Reset Type – The Reset parameter is a denite time reset method and the Type eld is
always set to Timed mode.
Reset Time, s – Enter the time delay for the denite 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 Denite-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 47 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 eld.
Sensitive Earth Fault
Overcurrent Protection Setting Denitions