Part Three Maintenance; Pole Unit; Contacts; Maintenance Of Contacts - Westinghouse DB-15 Instructions Manual

PART THREE

POLE UNIT

Each pole unit is mounted on a separate molded
base through which the breaker studs pass.
Fig. 6). The molded bases are attached to the steel
mounting panel and provide insulation for the break­
er studs.
The upper stud and contact are attached to the
molded base by one bolt.
pivoted on the molded base and attached to the
cross bar through insulating links. The series coil
and lower stud are fastened to the molded base by
three bolts.

Contacts.

(See Fig. 6). The DB-25 arcing con­
tacts should touch first on closing, open last on
opening, and have approximately a %2-inch gap
when the breaker is completely closed. This gap
is adjusted by removing the cross bar and screwing
the insulating link in or out on the stud. Be sure to
tighten the lock nuts after each adjustment.
The DB-15 contacts are adjusted to obtain lA-inch
horizontal travel of the cross bar after the contacts
first touch. As the contacts burn away it will be
necessary to adjust as described above for the DB-25.
Do not over-adjust as this will cause the opening
spring to compress to the solid position and thus
increase the closing effort. Check for over-adjust­
ment by manually pulling the moving contact away
from the stationary contact, with the breaker in the
closed position. It should be possible to obtain at
least lfs-inch gap between contacts.
2.
Table No. CLOSING SOLENOID CONTROL VOLTAGES AND CLOSING CURRENTS
NOMINAL
VOLTAGE
--------- ---------
12 V, D - C
24 V, D - C
48 V, D - C
125 V, D - C
250 V, D - C
110 V, 60 Cy
220V, 60 Cy
440 V, 60 Cy
*NOTE: For A - C closing use 3 - k va source or l a rger; f o r 2-pole breakers use a multiplier of .6
MAINTENANCE
(See
The moving contact is
MINIMUM VOLTAGE
AT COIL TERMINALS
Close Trip
---------
7
. . .
14
. . .
28
. . .
90 70
180 140
90 90
180 180
360
360
"DB" AIR CIRCUIT BREAKERS

Maintenance of Contacts.

spots should be removed with a file or sandpaper.
To replace the arcing contacts, open the breaker,
remove the arc chutes and then the stationary arc­
ing contacts. Close the breaker and remove the
moving arcing contacts. The new contacts can then
be added in the reverse order.
Caution:
All
power should be removed when
changing, maintaining or adjusting contacts.

OPERATING MECHANISM

The operating mechanism (see Fig. 6) is non­
adjustable and consists of a series of stainless steel
links designed to secure low closing and tripping
forces. To check for friction, raise the trip bar and
slowly rotate the manual operating handle in close
and trip direction. The linkage should follow the
handle without sticking.
A small quantity of oil is placed on th�dle
shaft, the roller lever roller, and the lat
the factory. The tripping load should not exceed
14 ounces measured at the trip screw.

CLOSING SOLENOID

The closing solenoid (see Fig. 6) is non-adjustable.
It is designed for intermittent duty only. Chec� for
loose bolts.
The minimum permissible control voltages at the
terminal of the closing coil, and the closing currents
at normal voltage are listed in Table No. 2 below.
*CLOSING CURRENT IN AMPERES AT NOMINAL
VOLTAGE FOR 3-POLE BREAKERS
OB-15 08·25
Close Close
-------- --------
. . . .
. . . .
. . . .
20 30
15
10
60 70
30 35
15 20
35-225-1
I.B.
Rough or high
08·15 and 08·25
Trip
-----------
18
9.5
5
2
1
1
.5
.2
13