I.L. 29C883E
l²t ramp function for trip units with catalog number suf-
fixes
LS
and
LSG.
A flat response time delay action is
provided by trip units with catalog number suffixes
LSI
and LSIG unless the instantaneous
(I) setting is selected.
3.4 Ground Fault Protection:
When selected, ground
fault pickup and time delay settings shown in Table
1-2
allow selective ground fault coordination with other circuit
protection devices.
An optional Automatic Trip Relay (ATR) may be furnished
with the circuit breaker and is mounted underneath the
trip unit as illustrated in Figure
4.
The ATR provides a
contact closure when a ground fault trip occurs. The con-
nections required are shown in
I.L.
4.0 PROTECTION SETTINGS
4.1 General
Prior to placing any circuit breaker in operation, each trip
unit protection setting must be set to the values specified
by the engineer responsible for the installation. The avail-
able settings along with the effect of changing the set-
tings are illustrated in Figures
2.1
to
2.4.
The installed rating plug establishes the maximum con-
tinuous current rating
(I,) of the circuit breaker. Short
delay current settings are defined in multiples of
I,.
Over-
ride is set at
One to four time and pick-up adjustment settings are
available depending on the particular trip unit purchased.
An eight position rotary switch is provided for each set-
ting. The rotary switch is adjusted using a small flatblade
screwdriver. The selected setting for each adjustment will
Digitrip RMS
31 0
Trip Units. Settings
7
and
8
are
available on 2500A styles.
4.3 Short Delay Time Settings
For catalog numbers
RESl
and
the short time delay is an
ramp config-
uration with the actual time delay a function if the trip cur-
rent involved
.
For catalog numbers
and
the short time delay is a flat response.
Four settings
(I,
0.1, 0.2, 0.3
second) are available (see
Figure
2.2).
The
setting gives a trip response with no
intentional delay (Instantaneous).
4.4 Instantaneous Pickup Setting
For catalog numbers
and
Instantaneous Pickup is achieved by set-
ting Short Delay Time to
(Instantaneous.) Short Delay
Pickup (see paragraph
4.2)
then becomes Instantaneous
Pickup.
4.5 Ground Fault Pick-up Setting
Eight settings lettered A through
K (there is no setting
marked
are available (see Figure
2.3)
and corre-
spond to the fixed ampere values listed on the trip unit
nameplate and in Table
1.2.
Note: These ampere values are always the same no
matter what rating plug is installed in the circuit
breaker.
Available on Catalog
Nos.
RESl
and
4.6 Ground Fault Time Settings
The ground fault time delay is a flat response with four
settings
0.15, 0.3,
0.5
second) available (Figure
2-4).
The
I setting gives a trip response with no intentional
delay (Instantaneous). This option is available on Catalog
Nos.
RESl
and
Effective
February 2006
3.2 Overload Trip:
In accordance with standards
requirements, the trip unit initiates a trip of the circuit
breaker within two hours for an overload of 135 percent,
and will trip in less time for higher overload currents.
A “Thermal Memory” effect prevents the breaker from
being re-energized immediately after an overload trip. A
“cooling off” period of up to
5
minutes is required, which
allows time for cabling to cool off.
3.3 Short Delay/Instantaneous Trip: For short circuit
appear in a small rectangular window in the trip unit
above the switch.
4.2 Short Delay Pick-up Setting
Seven settings are available that range from
2
to
8
(I,) as
shown in Figure
2.1.
This feature is included on all
CAUTION
LACK OF ILLUMINATION OF THE STATUS
LED DOES NOT INDICATE THE TERMINALS
OF THE BREAKER ARE DE-ENERGIZED
conditions that exceed the short delay pick-up settings,
the trip unit initiates a trip after a delay prescribed by the
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