40
S&C Instruction Sheet 681-530
Overcurrent Protection Setting Definitions
Low-Current Cutoff (Ground Protection)
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 modified 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 (Ground Protection)
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
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.
Definite-Time Current, A
– This is the current at which the
Definite Time
element
picks up.
Definite-Time Time, s
– This is the time delay at which the
Definite Time
Current
element picks up.
Reset Time Parameters (Ground Protection)
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. Accumulated value will
reset to zero after the
Reset Time
setting has elapsed.
