GE EntelliGuard G Application Manual page 12

Section 3. EntelliGuard TU Trip Unit System
whether it used for a retrofit kit on a 20 year old
ANSI circuit breaker or for a new production
EntelliGuard G circuit breaker.
• Traditional fuse shaped curves and thermal circuit
breaker type curves are now available. Regardless
of what mix of protective devices your system
includes – electronic trips, thermal magnetic circuit
breaker or fuses – the EntelliGuard TU has the
right curve shape to fit your system's needs.
• Ground Fault
• Short Time bands every 1/2 cycle where you need
them to optimize selectivity without sacrificing
any more protection than absolutely necessary.
• The industry's only true Zone Selective Interlocking
(ZSI) that works for Ground Fault, Short Time and
Instantaneous; with the ability to set the exact
clearing time of each circuit breaker when
restrained or unrestrained.
• A special Instantaneous algorithm that provides
the ability to use standard protection and simul-
taneously achieve selectivity while providing the
highest possible response and clearing. This
Instantaneous algorithm can be combined with
the ability to set an alternate Instantaneous
setting for maximum protection only when most
Figure 3.2
Maximum & Minimum Long Time Delay Bands
for a 1000A Long Time Pickup
1,000.00
100.00
22 Time Delay Bands
10.00
1.00
0.10
0.01
10 1,00
Amperes
10
Courtesy of NationalSwitchgear.com
10,000 100,000
needed, thus providing arc flash hazard control
while preserving complete
selectivity.
Terms
In: Trip Plug Rating in amperes. This is the current
rating of the rating plug installed in the trip unit.
This is the maximum Long Time pick up a trip unit
can have with a specific plug installed. A sensor
can usually be applied with plugs between 37.5%
or 40% to 100% of the sensor rating. Plugs are
labeled in amperes.
X: X is a multiplier that may be applied in front of
any rating value to denote a fraction of that rating.
Example: The Long Time Pickup may be set at 0.5X
of In.
HSIOC: High Set Instantaneous Overcurrent. Also
known as the Override. This is an Instantaneous
protection setting applied near the circuit breaker's
withstand rating required to clear high magnitude
faults quickly. In UL 489 CBs this is fixed, in UL
1066 CBs this may vary, if present at all.
MCR: Making Current Release (MCR). A setting
provided with each trip unit, based on the specific
circuit breaker size, used to protect the circuit
Figure 3.3
Maximum & Minimum Long Time Delay Bands
for a 1000A Long Time Pickup
1,000.00
100.00
10.00
22 Time Delay Bands
1.00
0.10
0.01
10 1,00
Amperes
10,000 100,000