GE Industrial Solutions EntelliGuard TU Trip Units - Manual (Page 21)

DEH-4567B EntelliGuard TU Trip Units: UL/ANSI Models
Protection
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INSTANTANEOUS PROTECTION
Adjustable Selective Instantaneous over current protection
causes an undelayed breaker trip when the chosen current
level and proper waveform is reached.
The pickup value may be set in steps of 0.5 xIn from 2.0 xIn
to 15 xIn and steps of 1 xIn from 15 xIn to a maximum of
30 xIn. Greater than 15xIn is available only in trips provided
with the “Extended Range Instantaneous” option on ANSI
EntelliGuard G circuit breakers.
The maximum possible setting depends on the trip unit
instantaneous option provided, the circuit breaker’s
withstand capability and whether or not ST has been
enabled.
When Instantaneous pickup is set above 15X without ST on,
ST pickup is automatically switched on Default delay is
automatically switched on at a minimum delay setting,
unless otherwise set by the user. This is only applicable to
EntelliGuard G.
Table 2-6: Maximum Instantaneous for Power Break I,
Power Break II, WavePro and AKR Trip Units
Frame
(A)
ANSI (X In) UL (X In)
With ST W/O ST With ST W/O ST
800 15 10 15 10
1,600 15 10 15 10
2,000 15 10 15 10
2,500 13 10
3,000 13 10
3,200 13 10
4000 9 9 9 9
5000 7 7
The Instantaneous pickup accuracy is +10%. On certain
ANSI trip units with the user-selectable switchable
instantaneous over current an additional value of OFF
appears at the end of the listing of numerical values. Note
that if Short Time Delay is set to off, you will not be able to
also turn off Instantaneous.
When Instantaneous pickup is set above the maximum
allowed for the CB without ST on, ST pickup is automatically
switched on at a default delay is automatically switched on
at a minimum delay setting.
WaveForm Recognition vs. Peak Sensing
WFR is the standard algorithm used in the normal
instantaneous trip function for all CB versions except
Power Break I. The WFR algorithm is specially designed to
optimize selectivity while achieving fast instantaneous
tripping of the circuit breaker. The algorithm’s
measurements act as a proxy for measuring energy and
hence are able to discern a fault current from a peak-let-
through current allowed to flow by a current limiting fuse
or current limiting circuit breaker while interrupting in a
current limiting manner. This allows the trip setting to be
set much lower than optimally peak sensing trips and
hence sensitive to lower arcing fault currents that could be
causing an arc flash event.
Reduced Energy Let Through (RELT)
The EntelliGuard TU trip unit’s RELT capability provides the
ultimate in user flexibility for wiring and controlling an
alternate Instantaneous setting for temporary use to
reduce personnel hazard.
All versions of the EntelliGuard TU trip units are available
with Reduced Energy Let-Through (RELT) Instantaneous
protection. This optional feature allows the trip unit’s
Instantaneous Protection pickup threshold to be
temporarily set lower when personnel are in close
proximity to the circuit breaker. In the event of a fault, the
trip unit will respond sooner, minimizing damaging arc
flash energy. Once personnel are safely clear of the area,
RELT is disengaged, returning the system to its normal
Instantaneous settings. The RELT setting is independent of
the normal adjustable selective Instantaneous. Even if the
normal instantaneous is not enabled, by turning on RELT
the instantaneous will then be enabled.
The pickup value may be set in steps of 0.5 xIn from 1.5 xIn
to 15 xIn or the maximum allowed instantaneous pickup
for the particular circuit breaker type, rating and size. The
RELT Instantaneous pick up clears fault current in 50
milliseconds or less. The maximum setting depends on the
trip unit catalog number, breaker type and frame, and
whether or not ST is enabled. See Table 8.
Clearing times for the various instantaneous functions vary
by circuit breaker. The RELT function clearing time is 0.042
seconds for EntelliGuard G at 60Hz and 0.05 seconds at
50Hz. The adjustable selective instantaneous is 0.05 and
0.06 seconds at 60 and 50 Hertz respectively. For Power
Break II, AKR, and WavePro circuit breakers the clearing
times are 0.05 and 0.058 seconds for RELT and selective
instantaneous respectively at 60 Hz. Power Break does not
offer the selective Adjustable Instantaneous or RELT
function. Instantaneous clears in 0.05 seconds for Power
Break versions of the EntelliGuard TU trip unit.
When the RELT option is configured in an EntelliGuard TU
Trip Unit Digital Input 1 and Digital Output 1 are
automatically and permanently configured to function with
RELT. RELT is a factory installed option—it cannot be
“turned on” if it is not purchased as an option. The Digital
Output will be energized whenever RELT protection is
engaged. The Digital Input can be wired to one or more
external contacts, such as a light curtain, to engage RELT
when someone is within range of the equipment.