Operation; Adjustment Of Settings; Replacing Overcurrent Devices - Westinghouse De-ion DB-15 Instructions Manual

barely trip the breaker.
necessary.
quarters tum to provide overtravel. This completes
•
the adjustment as the trip nut is self locking. Special
wrench S* 1809539 is recommended for adjusting
the trip nut on the center pole.
To remove an overcurrent tripping device from
the breaker, remove the three bolts, which hold the
tripping device to the breaker base.
moving the last bolt, hold the tripping device to
prevent it from falling.
The bottom assembly can be removed for repair
or replacement without removing the complete over­
current by removing the four comer 3 /16" screws
from the bottom of the overcurrent. The scaleplate
is applicable to its own bottom assembly and should
always be tied to it.
When replacing the bottom assembly make sure
that the bronze armature hinge pin bushings have
their flanges captive on the inside of the yoke side
plates
•

Operation

1-Dual Overcurrent Tripping Device for
Breakers, Fig. 7C
Overload currents above the setting of the long
delay pick-up adjustment (M) forces the armature
(B) and the trip saddle
the circuit breaker. This upward movement of the
armature (B) and diaphragm
sure in chamber ( G) causing air to be sucked in
through the timing valve
of the trip saddle
which air is permitted to enter chamber
valve (I). The reset valve
the parts after the breaker has been tripped.
Short circuit currents above the setting of the
instantaneous element as determined by adjustment
(N) causes the secondary armature (D) to be at­
tracted to the main armature (B).
movement of secondary armature (D) moves valve
(I) to wide open position, which removes restraint
on the movement of armature (B). The main arma­
ture (B) and trip saddle
the breaker.
2-Dual Selective Overcurrent Tripping Device
for Group and Tie Breakers, Fig. 7D
Several trials may be
Next tum the trip nut upwards three
BOTTOM ASSEMBLY
(H)
towards the trip bar of
(E)
reduces the pres·
(1).
The rate of travel
(H)
is determined by the rate at
(J)
allows quick reset of
(H)
move instantly to trip
The operation of this selective device is the same
as the dual overcurrent tripping device, except,
that in this case, the long delay and instantaneous
valve (I) in Figure 7C is replaced with a long delay
and short delay valve (I) Figure 7D, which operates
the same, except, when valve (I) Figure 7D is
forced down by the secondary armature on fault cur­
rents it controls the size of orifice to give the trip­
ping time required in the fault current short delay
Before re·
region.

Adjustment of Settings

Caution:
should be disconnected from the circuit before
making any adjustment.
By turning the adjustment knobs K-M-N Fig. 7C
and K-1-M-N Fig. 7D, the settings of the various
time and pick-up elements can be changed.
clockwise movement of any one of the knobs will
increase the setting and a counterclockwise move­
ment will decrease the setting.

REPLACING OVERCURRENT DEVICES

Instruction for Replacing Sealed Oil Overcurrent
Devices by Air Overcurrent Devices. Paragraphs 1
Load
and 4 only are required for breakers shipped after
March 1, 1954.
1. Remove the sealed oil overcurrent and discard
the mounting bolts.
sulated overcurrent are
2. Remove the lower studs and redrill the over­
current bolt holes to
lower coil terminal must fit inside this hole).
(G)
by
place when redrilled.
3. Loosen the three bolts holding the left and
center pole units to the panel and remove and
discard the present barriers (3P. breakers only).
Install the new barriers. The new barriers are not
symmetrical and consequently they cannot both be
The upward
slipped under the center pole unit as was the case
with the existing barriers.
sr� 1736180 should be assembled with bumper
blocks downwards; this requires one barrier to be
slipped under the left pole unit and the other under
the center pole unit. The DB-15 barriers Sri 1736179
should be assembled with the beveled comers up­
wards, by following the above procedure.
As a safety measure, the breaker
The proper bolts for the in­
g
iven in Table
(the bushing on the
21f:J2"
The DB-25 barriers
A
fl, 3.
Re­
21