S&C Vista SD - Appendix E; Accessories and Kits; Appendix F; Replacement Parts Information

S&C Instruction Sheet 695-535 33
Overcurrent Protection Setting Denitions
Definite-Time Phase Protection (Ground Protection)
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 Definite Time Phase Protection #1 element must be enabled for the Definite
Time Phase Protection #2 element to be enabled. When programming both the Definite
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.
Denite-Time Current, A – This is the current at which the Denite Time element
picks up.
Denite-Time Current, s – This is the time delay at which the Denite Time element
picks up.
Reset Time Parameters (Ground Protection)
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. Accumulated value will
reset to zero after reset time has elapsed.
(Negative Sequence Fault) Protection Element - Select to enable or disable
protection settings for the selected way. The Negative Sequence Fault element trips the
fault interrupter when the negative-sequence component of the three-phase currents
exceeds the pickup value for the time value set by the Inverse Curve or the Denite
Time settings.
Curve Family – Select the TCC curve family: IEC, IEEE, or Vista Coordination. 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.
Minimum-Trip Current, A – This is the current at which the inverse curve begins timing.
When using Vista Coordination curves, the minimum-trip current is set automatically
according to the ampere rating selected. For IEEE and IEC curves, enter the minimum
trip current value in increments of 1 ampere. The value should always be equal to or
lower than the low-current cutoff.
Time Multiplier – This is the time multiplier for the inverse curve. The time multiplier
is only used with IEEE and IEC curves.
Time Adder, s – This is the time adder for the inverse curve. The time adder is only used
with IEEE and IEC curves.
Negative Sequence