GE AKR-30S Manual page 22

Fault Trip Indicators
Indicators are designed to
reduce system downtime by
analyzing any overcurrent
fault and identifying its
cause. Mechanical pop-out
type indicators are available
on the programmer for
identifying overload or
short circuit overcurrent
faults when breakers are
ordered without integral
ground fault protection .
Indicators are available
to identify overload, short
circuit and ground fault trips
- for breakers supplied with
integral ground fault protec­
tion.
Zone Selective Interlocking
The standard means of
obtaining selectivity
between main and feeder
breakers is by incorporating
programmers with time­
coordinated trip characteris­
tics. This consists of setting
the farthest downstream
breaker with a small time
delay, and progressively
increasing the time delay as
you get closer to the main
protective device. The disad­
vantage in this method is
that the system must now
endure the stress of the high
current fault until time-out
occurs.
The Zone Selective Inter­
lock module, Figure 21. 1 ,
receives a signal from a
downstream MicroVersaTrip
programmer (Logic 0) which
causes the module to trans­
mit a low-level interlock sig­
nal to a MicroVersaTrip pro­
grammer upstream . The
interlock signal activates the
LED portion of an LED-
OVERLOAD
©
Transistor Opto-isolator in
the upstream programmer
causing the fixed delay band
to shift from "MIN" to the
programmer delay band
setting Figure 1 4 . 1 . Both the
Short-Time and Ground
Fault functions are capable
of being interlocked.
Zone Selective Interlock­
ing is available for the short­
time function and the
ground fault function, or
for the ground fault
function only.
SHORT CIRCUIT
GROUND FAULT
© ©
TRIP
INDICATOR
PUSH TO
RESET
Fig. 21.1 Multi-Zone Interlocking
21