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14
Figure 3-6 Type DS//-516 Pole Unit Assembly (Front
View)
ing circuit breaker operation within its compartment.
Each barrier is held firmly in place by its positioning in
the circuit breaker, with no fastener of any type required
(Figure 3-8).
To remove a barrier, carefully but firmly grasp the top of
the barrier and pull upward until it clears the circuit breaker
chassis. Note all cautions and instructions printed directly
on the barriers during removal or replacement. These
notes help to insure proper positioning of the barriers in
the circuit breaker.
In
addition, the barriers are designed
such that proper seating of the barriers cannot be accom-
plished, if the barriers are not replaced correctly.
3-6 DE-ION ARC CHUTES (INTERRUPTER
ASSEMBLIES)
The arc chutes mount on top of the pole units, well
down over the arcing contacts (Figure
3-1). This posi-
tioning confines arcs inside the chutes at all times and
for all values of current.
Each arc chute contains crosswise, vertical steel splitter
plates having an inverted "V" notch to attract the arc and
interrupt it, by essentially cooling and stretching the arc.
In
addition to steel plates, the larger arc chutes include
l.B.
694C694-02
Figure
3-7
Type DS//-516 Pole Unit Assembly (Rear
View)
hard, arc-resistant glass polyester plates. These plates
produce turbulence
in
the exhaust gases above the
steel plates, and prevent electrical breakdown over the
top of the arc chute or to ground. The arc chute compo-
nents are all assembled in an insulating jacket.
A CAUTION
NO ATTEMPT TO REMOVE THE ARC CHUTES
SHOULD BE MADE UNTIL STORED ENERGY
SPRINGS ARE COMPLETELY DISCHARGED.
Each arc chute is held in position by one top inserted
screw. To remove an arc chute, remove the mounting
screw and lift the arc chute out of the circuit breaker
(Figure 3-9).
3-7 ELECTRONIC TRIPPING SYSTEM
The electronic trip unit can be considered the intelli-
gence part of what is a three part, flux transfer tripping
system. The integrally mounted sensors and the trip
actuator make up the rest of the system (Figure
3-10).
All three parts of the system are discussed here. For
Effective
07
/97
Courtesy of NationalSwitchgear.com
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