Westinghouse DB-50 User manual

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Instructions for
Types DB-50, DBF-16 and DBL-50
Air Circuit Breakers
Westinghouse Electric Corporation
Switchgear Division, East Pittsburgh, Pa.
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LB. 33-850-3D, Effective May, 1970. Supersedes l.ll. 33-850-3-C, March, 1966.
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Page 2
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Table of Contents
Part 1 - Receiving, Handling, and Storing
Inspection.
Storing
Part 2 - Installation
Connections . . • . . . .
Part 3 - Maintenance
Pole Unit . • . . . • , • .
Contacts . .• . . • . • .
.. ... ... . .... " .. .. " ...... .
Maintenance of Contacts .
Operating Mechanism • . . . . . . . . . . • . . .
(Closing Spring Mechanism) Spring Closing Assembly
Closing Solenoid . . • . . , .
Overcurrent Tripping Device
Installation and Removal
Overtravel Adjustment •.
Construction • . . . . . . •
Time-Current Classification
Operation . . . . . . . . . .
Time-Current Characteristics
Adjustment of Calibration Settings
Control Relay ...•.. , . , •.
Shunt Trip Attachment . . • . , . . .
Undervoltage Trip Attachment .•...
Undervoltage Time Delay Attachment .
Reverse Current Trip Attachment .
Field Discharge Switch . , .
Auxiliary Switch . . . . . . .
Alarm Switch Attachment ..
Electric Lockout Attachment
Key Lock Attachment . . • ,
Key
Interlock Attachment . . • . , .. , • , . , . , ...
Rectifier Unit for A-c Undervoltage and A-c Electric Lockout
Attachments , . , . .
Type DBL-50 Breaker • . . . • • . • . • • . . • . . . • . • .
Page
5
5
6
9
9
9
9
9
9
12
14
14
15
16
16
21
21
24
26
27
27
27
28
30
30
30
32
32
34
36
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List of Illustrations
Figure
1
lA
2
3
3A
3B
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Page
Type DB-50 Fixed Circuit Breaker Outline Dimensions
and Mounting Details . . • • , , . . . . . . . • . , . . 7
Type
DB-50 Three Position Drawout Outline Dimensions 8
Typical Wiring Diagrams - Type DB-50 Fixed Circuit
Breaker . . . . . . . . . . . . . . . . . . . . . . . . 10
Cross-Sectional View of Type DB-50 Circuit Breaker. 11
Type DB-50 Spring Closing Assembly . , , , , , . . . 12
Type DB-50
Three Position Operating Mechanism. , , . , 13
Series Overcurrent Tripping Device with Long Delay and
Instantaneous Elements, , , . , , , , , , , , , , . , , , 14
Series Overcurrent Tripping Device Showing the Assembly
of Calibration Case to Magnetic Circuit . . . . . , . . . . 14
Cross-Sectional View of Series Overcurrent Tripping Device
with Long Delay and Instantaneous Elements , , , , , , 15
Tripping Characteristics of Standard Series Overcurrent
Tripping Device with Long Delay and Instantaneous
Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Tripping Characteristics of Selective Series Overcurrent
Tripping Device with Long Delay and Short Delay
Elements . . . . . . . . . . . . . . . . . . . . . . . . 18
Tripping Characteristics of Special Series Overcurrent
Tripping Device with Instantaneous Element Only .. , 19
Schematic Diagram of Standard Series Overcurrent Tripping
Device with Adjustable Long Delay and Adjustable
Instantaneous Elements. . . . . . . . . . . . . . . . . . . . 20
Schematic Diagram of Selective Series Overcurrent Tripping
Device with Adjustable Long Delay and Adjustable Short
Delay Elements , , , , . , , , , , . , . . , . , . , . , . . 22
Schematic Diagram of Series Overcurrent Tripping Device
with Instantaneous Element Only , . , 22
Discriminator for Tripping Device . • , , , , , . . , • , 23
Closing Solenoid - Construction Details , , , , , , • . . 24
Control Relay - Adjustment and Construction Details , , 25
Shunt
Trip Attachment - Location & Construction Details , 26
Undervoltage Trip Attachment - Construction Details , , 28
Undervoltage Time Delay Attachment - Construction Details 29
Reverse Current Trip Attachment - Construction Details , 29
Field Discharge Switch - Construction Details, , , , 31
Auxiliary Switch - Construction Details , , , . . , , , . . 31
Alarm Switch Attachment - Construction Details , , , , • 32
Electric Lockout Attachment - Construction Details, , , . 33
Key Lock or Key Interlock Attachment for Fixed Breakers -
Construction Details . • , , , . . . , , . , . , , , 34
Rectifier Unit for A-c Electric Lockout Attachment , 35
Type DBL Air Circuit Breaker , • , . , .•. , , , . 36
P_age 3
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Page 4
General
Type "DB" air circuit breaker is designed
to give continuous and reliable service as
the protective linkbetween the power source
,.
and associated productive equipment. This
breaker is built to operate with a minimum
of maintenance, while at the same time its
simplified construction permits maximum
accessibility for inspection and adjustment
when required. The ease with which at-
tachments may be added or removed is an
outstanding
feature of the "DB" design.
For the greatest measure of safety to
operating personnel and also to minimize
maintenance requirements, the breaker
should be mounted in an enclosure suitable
to local operating conditions. A selection
of standard enclosures is available for
various applications,
IMPORTANT: To assure proper functioning,
inspect each breaker at regular intervals in ac-
cordance with a
systematic maintenance schedule.
The frequency and character of the inspections
will for the most part be deterinined by these-
verity of the duty performed. The minimum re-
quirements, however, should
consist of a light
monthly
inspection, with a thorough inspection
semi-annually. Occasional
checks on calibra-
tion
as well as on coordination and freedom of
all moving
parts, must be included in the mainte-
nance sc.hedule. Consult Westinghouse engineer-
ing and
service personnel for recommendations
pertaining
to special operating or maintenance
conditions.
•
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Page 5
PART 1 - RECEIVING, HANDLING, AND STORING
Type "DB-50" air circuit breakers, with
all attachments mounted in place, are
shipped in special cartons.
Important: To avoid damage to the
breakers, do not use hooks in handling.
Net weights of Type DB-50 are given in
Table No. 1 below.
TABLE NO. 1 - Type DB-50
MANUAL
ELECTRIC
2-Pole
220 1 bs.
295 1 bs.
3-Pole
280 lbs.
355 1 bs.
Add 30 Lbs. for Drawout Details.
Add ~5 Lbs. for DSL Oeta i 1 s.
Immediately upon receipt, examine ship-
ment for any loss or damage incurred during
transit. If injury or rough handling is evi-
dent, file a damage claim at once with the
transportation company and notify the
nearest Westinghouse Sales Office.
When unpacking, be sure that no loose
parts are missing or left in the packing
material. Heport all shortages at once.
Blow out any dust or particles of packing
material that may have accumulated on the
circuit breaker parts. Do not remove tape
from top of arc chutes until breaker is to
be placed in service.
INSPECTION
The "DB" breaker assembly consists of a
coordinated group of sub-assemblies
mounted on a steel supporting panel. The
complete breaker assembly is to be mounted
with the steel panel in a vertical position,
All inspections for proper operation should,
therefore, be made with the breaker in this
position. Final inspection should preferably
be made with the breaker in its permanent
mounting.
Inspect the breaker as follows:
1. Haise and lower the trip bar by hand to
make sure that it does not bind.
2. Hotate the manual operating handle
slowly in a clockwise direction to move the
contacts toward the closed position,
a, Observe whether all parts are in
proper alignment and move freely.
b. Make certain that the studs have
not been forced out of alignment.
c. Be sure that the contacts are clean
and properly aligned. For a description of
contact alignment, refer to "Contacts",
Page 9.
3. If the contacts are in alignment and all
parts move freely, continue the clockwise
rotation until the breaker is latched,
4. Push the push-to-trip button to trip the
breaker.
a. The toggle linkage should collapse
and the moving contact assembly move
freely to the full open position. This should
be followed immediately by complete re-
setting of the links in the toggle mechanism.
b. The links must always be free to
move without friction or binding.
5. Check the attachments for opeTation in
accordance.with the appropriate instructions ·
as given under "Maintenance", Part 3 of
this book.
NOTE: It is not advisable to lubricate any parts
of the breaker. The lubrication supplied during
factory assembly is sufficient
for years of serv-
ice. The lubricant is of a special form which is
used sparingly. The addition of oil will only
pro-
mote the accumulation of dust and dirt.
STOHING
If circuit breakers are not to be installed
in their permanent location at once, they
should be carefully inspected for loose or
damaged parts· and then stored in a clean
dry place in an upright position to avoid
damage to the circuit breaker parts. A
covering of paper will prevent dust from
settling on the circuit breaker parts and is
preferred to packing or other materials
that are apt to absorb moisture. Hemove
the tape from the top of the arc chutes be- ·
fore placing in service,
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Page 6
PART 2 - INSTALLATION
Type "DB-50" circuit breakers are fur-
nished as complete unit assemblies and the
installation consists of: (1) bolting them to
the supporting framework or structure; (2)
connecting the current-carrying cables or
bus bars; and (3) completing any secondary
control wiring that may be necessary.
CAUTION: During installation, the circuit breaker
should be in the open position. Be sure to de-
energi
ze the load and control leads to be con-
nected,. and also the section of the switchboard
where installation is being made.
Mounting dimensions and details of the
front enclosure cutouts are shown in Fig. 1.
To prevent distortion of the breaker
panel, the supporting structure should be
checked for alignment.
CONNECTION~
Typical circuit breaker w1rmg diagrams
are shown in Fig. 2. The connecting cables
or bus bars should have adequate current-
carrying capacity, otherwise, heat will be
conducted to the circuit breaker resulting
in possible excessive temperature rise.
Connecting cables or bus bars must be
supported so that the circuit breaker studs
will not be subjected to unnecessary
stresses.
The circuit breaker studs and all con-
nections should be clean, smooth, and free
from burrs to assure full contact area.
They should be firmly clamped or bolted
in place to prevent excessive heating.
TABLE NO. 2
Closing Solenoid Control Voltages, Tripping Currents, Closing Currents and Fuse Ratings
CLOSING NOMINAL RECOMMENDED CLOSING
COIL CONTROL CLOSING TRIPPING
FUSE AMPERE RATING FUSE
BURDEN VOLTAGE AMPERES AMPERES STANDARD NEC STYLE NUMBER
250 VOLT
600 VOLT
24 DC
--- 9.5
48 DC
---
5.0
125
DC 18 2.0 10 120A823H04
250 DC 8 1.0 6 120A823H03
•·sTD. 230 AC 10
.5 6 120A823H03
460AC 5 .2 120A824H01
575 AC 4
.3
3 120A824H01
115 AC 20
1. 10
120A823H04
* For A-C closing use 3 KVA source or larger. Supplied for breakers having dual overcurrent tripping devices (Long Delay ..
Instantaneous Type) or for breakers having dual selective overcurrent tripping devices (Long Deloy .. Short Deloy Type)
plus discriminator details.
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CURRENT STUD ARRANGEMENTS
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Fig. 1 - Type DB-50 Fixed Circuit Breaker Outline Dimensions and Mounting Details
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Courtesy of NationalSwitchgear.com

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FOR 3 Y T 'sruos
POLE BKR. ~ t BKR~
'_ LOWER
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l STUDS
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f"RONT VIEW OF STUD LOCATIONS FOR
MOUNTING 3 POLE BREAKER WITH 2 OR 3
OVERCURRENT TRIPS OR 2 POLE BREAKER
WITHOUT REVERSE CURRENT TRIP
+ I c-P
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FIG 2 NEMA STD.
FRONT VIEW OF STUD LOCATIONS
FOR MOUNTING 2 POLE BREAKER
WITH 2 OVERCURRENT TRIPS
AND REVERSE CURRENT TRIP:
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CUTOUT IN DOOR
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19~----.
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OMITTED ON
2 POLE BKR.
POSITION _
1NDICATOR
ADDITIONAL
4 POJNT
AUX. SW.
4 POINT
AUX. SW.
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TEST "10S.
CONN POS.
MOVABLE
ESCUTCHEON
PLATE
MIN POSITION Of~ TC(
INTERLOCK PIN ' I l
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THE FOLLOWING ATTACHMENTS CAN
BE SUPPi.JED Wl1HOUT INCREASING
OVERALL DIMENSIONS:
1-AUXILIARY SWITCHES 02 CIRCUIT MAX.)
2. SHUNT TRIP
3-UNDERVOLTAGE TRIP (WITH OR W/TflOUT
TIM£ DELAY]
4.ALARM SWITCH
5 ELECTRIC LOCKOUT
6.0PERATION COUNTER
B
6FINGERS
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CONTACTS CAN BE
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HAND TRIP AND
PROVISON FOR
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BKR JN TB!PPED -11 t ' (I I :1
POS!TIClt\t. PAD-
LOCK FURNISH-
ED BY CUSTOM-
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CONTROL RELAY1
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2 FOR 2 POLE Il 20~~ .
REVERSE
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TRIP
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3 FOR 3 POLE
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Fig. IA - Type DB-50 Three Position Drawout Outline Dimensions
POSITION
'GROUND
FINGER
CONTACTS
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Page 9
PART 3 - MAINTENANCE
POLE UNIT
Each pole unit is mounted on a separate
molded base through which the breaker
studs pass. (See Fig. 3,) The molded bases
are attached to the steel mounting panel and
provide insulation for the breaker studs.
The upper stud and contact are attached
to the molded base by two bolts, The moving
contact is 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 four bolts.
Contacts. (See Fig. 3,)
The DB-50 arcing contact should touch first on
closing, open last on opening. Contact pressure on
the mains
is maintained by adjusting gap G to be
.050-.093 inches. 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.
Do not
over-adjust as this will cause the
contact springs to compress to the solid
position and thus increase the closing
effort. Check for over-adjustment by prying
the stationary arc tips open to at least
1/16-inch gap.
Maintenance of Contacts.
Rough or high 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 con-
tacts can then be added in the reverse
order.
CAUTION: All power should be removed when
changing,
maintaining or adjusting contacts.
OPERA TING MECHANISM
The operating mechanism (see Fig. 3) is
non-adjustable and consists of a series of
non-ferrous 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 di-
rection. The linkage should follow the handle
without sticking.
A small quantity of lubricant is placed
on the handle shaft, the roller lever roller,
and the latch plate at the factory.
CLOSING SPRING ASSEMBLY
The closing spring assembly is shown in
Fig, 3A.
Rotating the closing handle clockwise
raises the lift link and lower spring guide
to compl'ess the closing spring. Near the
end of the closing stroke the top end of the
lift link strikes the first toggle lever to
start the breaker closing. As the breaker
closes, the push rod raises the toggle link
and push link out of the toggle which permits
the closing spring to complete the breaker
closing.
Slow emergency operation to check the
contact sequence can be obtained by exerting
a slight closing pressure on the closing
handle and simultaneously pushing forward
on the breaker cross bar to start the breaker
closing.
Maintenance
Oil the pins and slides every 10,000 op-
erations.
CLOSING SOLENOID
The closing solenoid (see Fig. 14) is non-
adjustable. It is designed for intermittent
duty only. Check for loose bolts.
To remove closing coil, trip breaker.
Disconnect closing coil leads from control
circuit wiring. Take off bolts (9), washers'
(12), relay release arm (8), bolts (10),
washers (11) and plate (2). Drop closing
coil (7) with brass tube (5).
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Page 10
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