GE Industrial Solutions Spectra RMS Molded Case - Manual (Page 20)

GEH-702 Users Manual
19
Ground Fault Delay (Trip or Alarm) (Optional)
This set point is used to allow momentary ground fault
currents without nuisance tripping the breaker. It is also
used to establish the shape of the ground fault time
current curve. Fifteen time delay bands and four curve
slopes are available (slope equal to zero represents
zero slope or I 2 t OUT). The ground fault time delay is a
function of both the time delay band and the slope.
Figure 15. Ground Fault Delay
Zone Selective Interlock (ZSI) (Optional)
Zone Selective Interlock set points are available for
Short Time (ST) and Ground Fault (GF). The set point
includes the pickup, time delay, and slope parameters.
The ZSI Short Time pickup setting is used to establish
the ST pickup of the trip unit when another ZSI trip unit
signals it . The ZSI ST pickup is calculated by multiplying
the ZSI ST pickup value times the breaker’s nominal
ampere rating “C”. It is important to note that changes
to the long time pickup value affect the ZSI ST pickup
value. The available range of ZSI ST pickup values is 1.5
to 9.0 in increments of 0.5.
The ZSI ST delay setting is used to establish the ST delay
of the trip unit when another ZSI trip unit signals it. This
setting is used to allow momentary inrush currents
without nuisance tripping the breaker. Twelve time
delay bands and four curve slopes are available. The
ZSI ST delay is a function of both the time delay band
and the slope.
The ZSI Ground Fault pickup setting is used to establish
the GF pickup of the trip unit when another ZSI trip unit
signals it . The ZSI GF pickup is calculated by multiplying
the ZSI GF pickup value times the breaker’s sensor
value “S”. The available range of ZSI GF pickup values is
0.4 to 1.0 in increments of 0.05.
The ZSI GF delay setting is used to establish the GF
delay of the trip unit when another ZSI trip unit signals
it . This setting is used to allow momentary inrush
currents without nuisance tripping the breaker. Fifteen
time delay bands and four curve slopes are available.
The ZSI GF delay is a function of both the time delay
band and the slope.
NOTE - the trip unit’s primary ST pickup value is
interdependent with the ZSI ST pickup value. Changing
the ZSI ST pickup value automatically changes the
primary ST pickup value to the same value as the ZSI ST
value. This interdependency also applies to the ZSI GF
pickup and the trip unit’s primary GF pickup setting.
Zone Selective Interlock is also available for the
instantaneous (INST) trip function. This feature only
functions as an output signal to an upstream trip unit
optioned with ZSI INST (Spectra microEntelliGuard
TM
breakers cannot accept a ZSI INST input signal).
With this feature enabled, a ZSI signal is sent to the
upstream trip unit when the trip unit responds to an
instantaneous inrush current. No settings are available
for the ZSI Instantaneous set point other than enabling
the feature per the table below.
There are multiple combinations of ST/GF/INST that can
be enabled. The available combinations of setting ZSI
are as follows: