Page
42
Table
4.
1 Sensor
and
Limiter Ratings
Breaker
Sensor
Limiter
Ratings
Type
Rating
B
Recommended
*Minimum
**Maximum
DSLll-30S
SODA
1600A 1200A
2000A
DSLll-30S
600A
1200A
SODA
2000A
DSLll-30S
Less
than
1200A
125%
or
more
2000A
600A
of
sensor
rating
DSLll-516
1600A
3000A 3000A 3000A
DSLll-516
1200A
2500A 2000A
3000A
DSLll-516
Less
than
2000A
125%
or
more
3000A
1200A
of
sensor
rating
DSLll-620
2000A
3000A 3000A 3000A
11
Minimizes
nuisance
blowing
of
limiters
*
Use
only
when
current
limiting
is
required
for
downstream
equipment.
If
long
delay
pick-
up
is
set
above
100%,
minimum
limiter
ratings
should
not
be
used.
**
Highest
rating
that
will
protect
breaker.
trucks. They are used
in
series with DSll-632 and DSll-
840 circuit breakers respectively. This separate mounting
is made necessary by the size of the fuses and their high
temperature characteristics.
4-6.1 DSLll CURRENT LIMITERS
Do not replace limiters with sizes other than permitted
by Table
4.1. DSLll current limiters have been tested
and approved by Underwriters Laboratories, Inc. for use
in DSLll circuit breakers when applied according to
Table
4.1. They are not electrically or physically inter-
changeable with current limiting fuses of any other
design.
The current limiters are held in place
in
an extension
provided on the back of the circuit breaker (Figure
4-16).
This extension makes the DSLll circuit breaker eight
inches deeper than the corresponding DSll circuit
breaker. The current limiters can only be removed from
the circuit breaker and replaced when the circuit breaker
is removed from its associated compartment. For this
reason there is no fixed mounted version of the DSLll
circuit breaker.
4-6.2 BLOWN LIMITER INDICATOR
The blown limiter indicator provides a visual indication
on the front of the DSLll circuit breaker when a current
limiter in
any
phase has interrupted a short circuit. It
also insures that the circuit breaker will be tripped when
any current limiter has blown. This prevents single
l.B.
694C694-02
Figure 4-16 DSL//-516 Circuit Breaker (Side View)
phase power from being applied to a three-phase load
(Figure
4-17).
The indicator device consists of three solenoids, each
connected in parallel with one of the limiters. When a lim-
iter is blown, the resulting voltage across the open limiter
causes the associated solenoid to operate. Operation of
the solenoid trips the circuit breaker mechanically and
extends an indicator through the front cover of the circuit
breaker (Figure
3-2). The indicator will remain extended
and the breaker will be held trip-free until the reset button
is pushed. If the device is reset and the breaker reclosed
on an energized circuit before the blown limiter is
replaced, the breaker will immediately be reopened and
held trip-free. The solenoids are isolated from the prima-
ry circuit voltage by three transformers located above the
limiters (Figures 3-2 and
4-16).
4-6.3 FUSE TRUCK
DSll-FT32 and DSll-FT40 fuse trucks provide drawout
mounting for current limiting fuses when installed in low
voltage switchgear. These drawout trucks physically fit in
the same compartment as the DSll-632 and DSll-840 cir-
cuit breakers respectively. They are moved in and out of
the compartment using a similar levering mechanism as
provided on DSll circuit breakers (Figure
4-18 and 4-19).
Effective
07
/97
Courtesy of NationalSwitchgear.com
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