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.
I. D. 33·8.50.JL', Effective March, 1966. Supcrsl'dC's I. B. .l'l·H50·3-B, May, 1965.
Courtesy of NationalSwitchgear.com

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lable of Contents
Part 1 - Receiving, Handling, and Storing
l nspecti on .
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 Hemoval
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 ,
Heverse Current Trip Attachment.
Field Discharge Switch ,
Auxiliary Switch .. , .. , .
Alarm Switch Attachment •.
Electric Loclrnut Attachment
Key Lock Attachment , .•.
Key Interlock Attachment •.
Hectifier Unit for A-c Undervoltage and A-c Electric Lockout
Attachments •. , , .
Type DBL-50 Breaker .................... .
Page
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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
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24
25
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Type DB-50 Fixed Circuit Breaker Outline Dimensions
and Mounting Details . . . • . . . . . . . . . . . • • .
Type DB-50
Three Position Drawout Outline Dimensions
Typical Wiring Diagrams -Type DB-5U Fixed Circuit
Breaker . . . . . . . .. . . . . . ~ . . . . . . . . -. .
Cross-Sectional View of Type DB-50 Circuit Breaker.
Type DB-50 Spring Closing Assembly .....•.•.
Type DB-50 Three Position Operating Mechanism .•.
Series Overcurrent Tripping Device with Long Delay and
Instantaneous
Elements. . . . . . . . . . . . . . . . . .
Series Overcurrent Tripping Device Showing the Assembly
of Calibration Case to Magnetic Circuit . . . . • . . . . .
Cross-Sectional View of Series Overcurrent Tripping Device
with Long Delay and Instantaneous Elements • . . • . •
Tripping Characteristics of Standard Series Overcurrent
Tripping Device with Long Delay and Instantaneous
Elements ........................ .
Tripping Characteristics of Selective Series Overcurrent
Trip1Jl.ng Device with Long Delay and Short Delay
Elements . , . . . ·. . . . . . . . . . . . . , . . . . .
Tripping Characteristics of Special Series Overcurrent
Tripping Device with Instantaneous Element Only • . • •
Schematic Diagram of Standard Series Overcrnrrent Tripping
Device with AdjustalJle Long Delay and Adjustable
Instantaneous Elen1ents. . . . . . . . . . . . . . , . . . . .
Schematic Diagram ofSelective Series Overcurrent Tripping
Device with Adjustable Long De.lay and Adjustable Short
Delay Ele1nents . . _. . . . . . . . . . . . . . . . . . . . .
Schematic Diagram of Series Overcurrent Tripping Device
with
Instantaneous Element Only . • . . . • . . . .
Discriminator for Tripping Device . , •...•.•••.
Closing Solenoid - Construction Details . • • . • . • . .
Control Relay - Adjustment and Construction Details ..
Shunt Trip Attachment -Location& Construction Details .
Undervoltage Trip Attachment - Construction Details .•
Undervoltage Time Delay Attachment - Construction Details
Reverse Current Trip· Attachment - Construction Details .
Field Discharge Switch - Construction Details ..
Auxiliary Switch - Construction Details . . • • . . . • . .
Alarm Switch Attachment - Construction Details . • . • •
Electric Lookout Attachment - Construction Details .•••
Key Lock or Key Interlock Attachment for Fixed Breakers -
Construction Details. . . . . . . . . . . . . . . . ,
Rectifier Unit for A-o Electric Lookout Attachment •
Type DBL
Air Circuit Breaker . , , ...•...•.
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General
Type "DB" air circuit breaker is designed
to give continuous and
reliable service as
the protective link betweenthe power source
and associated productive equipment, This
L>reaker is built to operate with a minimum
of
maintenance, whilE! at the same time its
simplified constructidn 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 determined by the se-
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 wel I as on coordination and freedom of
all moving ports, must be included in the mainte-
nance schedule. Consult Westinghouse engineer-
ing
and service personnel for recommendations
pertaining to special operating or maintenance
conditions.
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PART 1 • RECEIVING, HANDLING, AND STORING
Type "DB-50
11
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 lbs,
295 Ibs,
3-PoI e
2.80 I bs.
355 Ibs.
Add 30 Lbs. for Drawout Details.
Add ~5 Lbs. for DBL Details.
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. Report 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 tobe 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 inspectionshould preferably
be made with the breaker in its permanent
mounting.
Inspect the breaker as follows:
1. Raise and lower the trip bar by hand to
make sure that it does not bind.
2. Rotate the manual operating handle
slowly in a clockwise
direction to move the
contacts toward the closed position. ·
a, Observe \\·bether all pnrts are in
proper alignment and move freely.
b. Make certain that the studs have
not been forced out
of alignment.
o. Be sure that the contacts are clean
and properly aligned. For a dc5Cription 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 mechantsm.
b. Tbe links must always be free to
move without
friction or binding.
5. Check the
attachments for operation in
accordance with the appropriate instructions
as given under "Maintenance", Part 3 of
this book.
NOTE: It is not advisable lo lubricate any ports
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.
STORING
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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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) completinp; any scconclary
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.
Typical circuit ln·\·al\cr wiring diagrams
are shown in Fig. 2, The connecting cables
or bus bars should have adequate current-
carrying cap'1city, otlw,·w'o'C, heat will be
conducted to the circi.;it
breaker resulting
in possible cxcc:'.S'.\C tc:Tq1crature rise.
Connecting cables or bus bars must be
supported so thB t the circuit brreaker 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 Voltage.s, Tripping Ct1t'rents1 Closing Currents and Fuse Ratings
---
-·---
.
Cl.OSI NG NOMINAL
RECOMMENDED CLOSING
COIL
CONTROL
CLOS I HG TRIPPING FUSE AMPERE RATING
FUSE
SURDEH VOLTAGE
AMPERES AMPERES STANDARD NEC STYLE
NUMBER
250 VOLT 600 VOLT
'--
-
-------
~----
---
211
DC
---
9. 5
48 DC
---
5.0
125 DC 18
2.0
10
I 20A823H04
250 DC
8 I. 0 6 I
20A823 ll03
' STD.
230 AC 18
r
• 0
10
I 20A823 H05
460 AC 8 .2 6
120A82'1H03
575 AC 4 .3 3
120A824HOI
115 AC
---
I.
24
DC
---
9.5
48 DC
---
5.0
125 DC
128 2.0
40
120A823HIO
250 DC 62 I.0
25
120A823tl07
L HIGH
230 AC 80
. 5
25
I 20A823110'1
460 AC 39 .2
15
120A8241105
575 AC
25
.3
10
120A824 H04
115 AC
---
I.
*For A-C closing use 3 KVA source or larger. Supplied fot breakors hoving dual overcurrent tripping devices (Long Deloy •
Instantaneous Type) or for breakers having dual selective ovorcurrenl tripping devices (Long Deloy· Short Delay Type)
plus discriminator details,
6May be supplied for match up breakers having dual seloctive overcurrent tripping devices (Long Delay~ Short Delay Type)
without discriminator details.
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CURRENT STUD ARRANGEMENTS (FRONT VIEW)
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Fig. l - Type DB-50 Fixed Circuit Breaker Out!1lie Dimensions and Mounting Detail$
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fr'F t·U~PER
FOR
3 ! .
S.UDS
POLE BKR ' ,
~ fBKR I
~- J,,l LOWER
·- · STUDS
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FRONT V!(W Of ST\.JD LOCATIONS FOR
MOUNTING 3 POLE BREAw:;ER WITH 2 OR 3
OVERCURRE:NT TR1PS OR 2 POLE BREAKER
WITHOUT REVERSE CURRENT TRIP
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(BKR.
ca+
flSzL_,"JFMA STD
FRONT VlEW OF STUD LOCATIONS
FOR MOUNT!NG 2 POLE BREAKER
WiTH 2 OVfRCURRENT TRIPS
AND REVERSE CURRENT TRIP.
DOOR
HANDL
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CUTOUT IN DOOR
THE "°OLLOWING ATTAQ-lMENTS CAN
BE SUPPi.JED Wl1HOUT INCqEASJNG
OVERALL D!MENS!ONS:
l. AUXQJARY SWITCHES Qz CIRCUIT MAX.)
2 SHUNT TRIP
3 UNDERVOLTAGE TRIP (V'llTH OR Wli"!'IOUT
TJMf DELAY)
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4_ALARM SWITCH ! l
5.(LECTRIC LOCKQ!..JT I I
6 OPERATION COUN"TER: l I
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12 FINGERS
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f lI ·a§ 12 OR 24 Sl'COND<KV
~y"ONTACTS CA~ SE
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~EL BASE $uP.Pi :JED. l~~>=l i2
t_ CAN 8E OM• 1 TtD
t== 19_1_
~ pt~~+-6---j
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OMITTED ON
2 POLE BKR~
POSITION.
INDICATOR
AOOTIONAL
4 POJNT
AUX. SW.
-4 POINT
AUX'. SW
l~AN~t '£7'1! / I f i)
TEOC n1'I "111'
IN, Rl l'i , . ' \ 1; •
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HANO TP.!P ~D f
PROVIS!ON FORil
PAOLOCKJt.,K; i • ~
BKR _IN TRIPPED;! : j'U
POSI 1 J()N. PAD- •
1
w·
LOCK FURNISH-] I '1
ED BY CUSTOM-1 I I +
ER lj , .___L_f
CONTROL RELAY·'
Ol/ERCLIRRENT-
TRJP
2 FOR 2 POLE
3 FOR 3 PC:tf
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01SCONN. POS.l
TEST ?QS_ ~\
CONN POS
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MAX_ TRiP POSl llON --j-:t+- - 1'(01-.(TA,_ 5 I
OF INTERLOCK PlN \ l l:: Q
M!N POSITION Of
lNTERLOCw:; PIN
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3
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u11 AS CELL INTERL00\ ··1l, ... ',~
' I I I IS OPERATED BRK ~~+----'\\.. '
Ji... ~...f SOLENOID TRIPS BEFORE THIS -itt-~2-----=:r'-it-o-REE POSITtON
rz~ ,j U DIM IS EX~EEDED !'~" t- ·j -·-l~OUND
] l:ill~ 18]12 Se---1 F!NGER
j"--3~ 28 CON"TACTS
REVERSE
Fig. IA - Type DB-50 Three Position Drawout Outline Dimensions
• •
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Courtesy of NationalSwitchgear.com

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Page 9
PART 3 - MAINTENANCE
POLE UNIT
Each pole unit is mounted on a separate
molclecl base through which the breaker
studs pass. (See Fig. 3.) The rnol ded bases
are attached to the steel mounting panel and
provide insulation for the bre:tker studs.
The upper stud and co:1hc\ arc attached
to the molded
base by two bolts. Tho 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 ad-
justing gap G to be .078-.093 inches. This
gap is acljustecl 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.
OPEHATING 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.
notating the closing handle clockwise
raises the lift link and lower spring guide
to
compress 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 ofthe togglewhich permits
the closing spring to complete the breaker
closing.
Slow emergency operation to check the
contact sequence can be obtainedby 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. lt is designed for intermittent
duty only. Check for loose bolts.
To remove closing coll, 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).
Courtesy of NationalSwitchgear.com

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Courtesy of NationalSwitchgear.com