S&C Vista - Sensitive Earth Fault

42 S&C Instruction Sheet 681-530
Definite-Time Phase Protection (Negative Sequence)
Denite-Time Protection Elements (Element #1 and Element #2) Select to enable
or disable protection settings for the selected way. Denite Time selection is available
if a IEC, IEEE, or Vista coordination phase TCC curve is selected or if no TCC curve is
specied for phase protection. Denite-Time Phase Protection settings will trip the
fault interrupter if the selected current exceeds the setting value for the specied time
setting.
The Denite Time Phase Protection #1 element must be enabled for the Denite
Time Phase Protection #2 element to be enabled. When programming both the De-
nite Time #1 element and the Denite Time #2 element, the Denite Time #2 element
must be set at a higher current and a faster speed than the Denite Time #1 element or
an error will occur. The Denite Time #1 and Denite 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.
Denite-Time Current, A – This is the current at which the Denite Time element
picks up. (Denite-Time Element 1 or Element 2.)
Denite-Time Time, s – This is the time delay at which the Denite Time Current
element picks up. (Denite-Time Element 1 or Element 2.)
Reset Time Parameters (Negative Sequence)
Reset Type – The Reset parameter is a denite time reset method and the Type eld is
always set to Timed mode.
Reset Time, s – Enter the time delay for the denite 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 Denite-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 eld.
Minimum-Trip Current, A – This is the current at which the inverse curve begins timing.
Sensitive Earth Fault
Overcurrent Protection Setting Denitions