Westinghouse DB-75 User manual

Instructions
for
Types
DB
-
75
,
DB
-
100
and
DBF
-
40
Air
Circuit
Breakers
600
volts
A
-
C
250
Volts
D
-
C
Continuous
Current
Rating
DB
-
75
DB
-
100
4
,
000
Amperes
5
,
000
Amperes
/
D
-
C
6
,
000
Amperes
{
Only
2
,
000
Amperes
2
,
500
Amperes
,
3
,
000
Amperes
Westinghouse
Electric
Corporation
Switchgear
Division
,
East
Pittsburgh
,
Pa
.
I
.
B
.
33
-
850
-
4
&
5
D
,
Effective
November
,
1966
.
Supersedes
I
.
B
.
33
-
850
-
4
&
5
C
,
May
,
1962
.
Courtesy of NationalSwitchgear.com

.
v
’
i
TABLE
OF
CONTENTS
RECEIVING
,
HANDLING
AND
STORING
Page
7
Part
One
7
Inspection
Storing
..
.
7
INSTALLATION
Pages
8
-
11
Past
Two
8
Connections
Enclosures
.
.
8
MAINTENANCE
Pages
12
-
24
Part
Three
14
Pole
Unit
Contacts
Maintenance
of
Contacts
.
Operating
Mechanism
Closing
Solenoid
.
Overcurrent
Tripping
Device
Description
.
Construction
Installation
and Removal
Adjustment
of
Trip
Screw
Operation
Standard
Overcurrent
Tripping
Device
Selective
Overcurrent
Tripping
Device
Instantaneous
Overcurrent
Tripping
Device
(
Single
Element
)
Time
-
Current
Characteristics
Calibration
^
Maintenance
X
Control
Relay
Inspection
Maintenance
Shunt
Trip
Attachment
Inspection
Maintenance
Undervoltage
Trip
Attachment
Undervoltage
Time
Delay
Attachment
Inspection
Maintenance
.
..
.
.
Auxiliary
Switch
Inspection
Maintenance
14
14
i
.
<
14
17
k
18
i
-
.
-
18
18
18
f
19
20
20
21
22
22
23
23
24
24
24
24
24
24
24
26
26
26
26
26
26
(
)
2
Courtesy of NationalSwitchgear.com

TABLE
Part
Three
MAINTENANCE
(
Continued
)
Pages
24
-
30
Alarm
Switch
Attachment
.
Inspection
Maintenance
Electric Lockout
Attachment
.
Inspection
Maintenance
Key
Lock
Attachment
,
Inspection
Maintenance
Key
Interlock
Attachment
Inspection
Maintenance
Rectifier
Unit
for
A
-
C
Undervoltage
and
A
-
C
Electric Lockout Attachments
Inspection
.
Maintenance
Reverse
Current
Trip
Attachment
Inspection
Maintenance
Field
Discharge
Switch
Recommended
Spare
Parts
26
26
29
29
29
29
29
29
30
30
30
30
30
30
30
30
30
31
•
S
'
33
V
34
v
.
(
T
1
3
Courtesy of NationalSwitchgear.com

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LIST
OF
ILLUSTRATIONS
Page
Figure
1
DB
-
75
Outline
and
Mounting
Dimensions
1
A
DB
-
100
Outline
and
Mounting
Dimensions
IB
DBF
-
40
Outline
and
Mounting
Dimensions
1
C
DB
-
75
Outline
and
Mounting
Dimensions
2
Typical
Wiring
Diagrams
3
Cross
-
Sectional
View
of
DB
-
75
and
DB
-
100
Circuit
Breakers
3
A
DB
-
75
and
DB
-
100
Three
Position
Operating
Mechanism
4
Adjusting
Limits
of
Main
and
Arcing
Contacts
for
DB
-
75
and
DB
-
100
Cir
-
cuit
Breakers
5
Closing
Solenoid
—
Construction
Details
.
6
Cross
-
Sectional
View
of
Overqurrent
Tripping
Device
with
Long
Delay
and
Instantaneous
Elements
.
7
Schematic
and
Typical
Time
-
Current
Characteristics
of
Overcurrent
Trip
-
ping
Device
with
Long
Delay
and
Instantaneous
Elements
8
Cross
-
Sectional
View
of
Overcurrent
Tripping
Device
with
Long
Delay
and
Short
Delay
Elements
8
A
Selective
Overcurrent
Trip
Operations
9
Schematic
and
Typical
Time
-
Current
Characteristics
of
Overcurrent
Trip
-
ping
Device
with
Long
Delay
and
Short
Delay
Elements
10
A
Schematic
Diagram
of
Overcurrent
Tripping
Device
with
Instantaneous
Element
Only
10
B
Typical
Time
-
Current
Characteristics
of
Overcurrent
Tripping
Device
with
Instantaneous
Element
Only
11
Control
Relay
—
Construction
Details
.
'
12
Shunt
Trip
Attachment
—
Construction
Details
13
Undervditage
Trip
Attachment
—
Construction
Details
.
14
Undervoltdge
Time
Attachment
—
Construction
Details
15
Auxiliary
Switch
—
Construction
Details
16
Alarm
Switch
Attachment
—
Construction
Details
17
Electrical
Lockout
Attachment
—
Construction
Details
18
Key
Lock
or
Key
Interlock
Attachment
—
Construction
Details
19
Rectifier
Unit
for
A
-
C
Undervoltage
and
Electrical
Lockout
Attachments
.
.
.
.
31
20
Reverse
Current
Trip
Attachment
—
Types
"
DB
-
75
"
and
“
DB
-
100
"
Air
Circuit
Breakers
21
Cross
-
Section
View
of
Field
Discharge
Pole
Unit
9
10
11
12
13
15
16
17
18
19
20
21
22
.
/
<
•
/
-
23
24
t
:
24
;
i
25
1
26
27
28
28
29
29
30
32
33
;
v j
4
Courtesy of NationalSwitchgear.com

\
*
3
LB
.
33
-
850
-
4
&
5
D
“
DB
”
AIR
CIRCUIT
BREAKERS
WESTINGHOUSE
"
AIR
CIRCUIT
BREAKERS
w
TYPE
Type
"
DB
"
air
circuit
breaker
is
designed
to
give
continuous
and
reliable
service
as
the
protective
link
between
the
power
source
and
associated
pro
-
ductive
equipment
.
This
breaker
is
built
to
operate
with
a
minimum
of
main
-
tenance
,
while
at
the
same
time
its
simplified
construction
permits
maximum
accessibility
for
inspection
and
adjustment
when
required
.
The
ease
with
which
attachments
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
min
-
imize
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
reg
-
ulai
^
intervals
in
accordance
with
a
systematic
maintenance
schedule
.
The
frequency
and
character
of
the
inspections
will
for
the
most
part
be
determined
by
the
severity
of
the
duty
performed
.
The
minimum
requirements
,
however
,
should
consist
of
a
light
monthly
inspection
,
with
a
thorough
inspection
semi
-
annually
.
Occasional
checks
on
cali
-
bration
as
well
as
on
coordination
and
freedom
of
all
moving
parts
,
must
be
included
in
the
maintenance
schedule
.
Consult
Westinghouse
engineering
and
service
personnel
for
recommendations
pertaining
to
special
operating
or
maintenance
conditions
.
.
*
r
5
Courtesy of NationalSwitchgear.com

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Courtesy of NationalSwitchgear.com

I
.
B
.
33
-
850
-
4
&
5
D
“
DB
”
AIR
CIRCUIT
BREAKERS
PART
ONE
RECEIVING
,
HANDLING
AND
STORING
TYPES
“
DB
-
75
”
AND
“
DB
-
100
”
AIR
CIR
-
CUIT
BREAKERS
are
shipped
in
wooden
crates
with
all
attachments
mounted
in
place
.
Important
:
To
avoid
damage
to
the
break
-
ers
,
do
not
use
hooks
in
handling
.
a
.
Observe
whether
all
parts
are
in
proper
alignment
and
move
freely
.
b
.
Be
sure
that
the
contacts
are
clean
and
properly
aligned
.
The
center
finger
of
the
stationary
arcing
contacts
should
have
a
slight
lead
.
C
.
The
hinge
end
of
the
moving
contact
is
lubricated
with
graphite
grease
and
is
therefore
black
.
For
a
description
of
contact
alignment
refer
to
"
CONTACTS
"
,
Page
14
.
4
.
If
the
contacts
are
in
alignment
and
all
parts
move
freely
,
continue
the
closing
until
the
breaker
is
latched
.
5
.
Hold
the
maintenance
operating
handle
down
.
Push
the
"
Push
to
Trip
"
button
to
trip
breaker
.
a
.
The
toggle
linkage
should
collapse
and
the
moving
contact
assembly
move
freely
to
the
full
open
position
.
This
should
be
followed
by
complete
resetting
of
the
links
in
the
toggle
mechanism
as
the
handle
is
raised
.
b
.
The
links
must
always
be
free
to
move
with
-
out
friction
or
binding
.
6
»
Check
the
attachments
for
operation
in
accord
-
ance
with
the
appropriate
instructions
as
given
under
"
Maintenance
"
,
Part
III
of
this
book
.
Note
:
It
is
not
advisable
to
lubricate
any
parts
o
£
the
breaker
.
The
lubrication
supplied
during
factory
assembly
is
sufficient
for
years
of
service
.
The
lubricant
is
of
a
special
form
which
is
used
sparingly
.
The
addition
of
oil
will
only
promote
the
accumulation
of
dust
and
dirt
.
I
Table
No
.
1
NET
WEIGHTS
OF
3
POLE
BREAKER
DB
-
75
475
lbs
(
Add
50
lbs
for
D
.
O
.
)
DB
-
100
525
lbs
(
Add
75
lbs
for
D
.
O
.
)
DBF
-
40
550
lbs
(
Add
75
lbs
for
D
.
O
.
)
Immediately
upon
receipt
,
examine
shipment
for
any
loss
or
damage
incurred
during
shipment
.
If
injury
or
rough
handling
is
evident
,
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
.
INSPECTION
The
"
DB
"
breaker
assembly
consists
of
a
co
-
or
-
dinated
group
of
^
ub
-
assemblies
mounted
on
a
sup
-
porting
panel
.
The
^
complete
breaker
assembly
is
to
be
mounted
with
the
panel
in
a
vertical
position
.
All
inspections
for
proper
operation
should
,
therefore
,
be
made
with
the
breaker
in
this
position
.
Final
in
-
spection
should
preferably
be
made
with
the
break
-
er
in
its
permanent
mounting
.
Inspect
the
breaker
as
follows
:
1
.
Lift
trip
finger
by
hand
to
make
sure
that
it
does
not
bind
.
2
.
Remove
any
foreign
particles
from
the
hinge
end
of
the
moving
contacts
.
3
.
Insert
the
maintenance
operating
handle
and
slowly
close
the
breaker
.
STORING
If
circuit
breakers
are
not
to
be
installed
in
their
permanent
locations
at
once
,
they
should
be
care
-
fully
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
which
are
apt
to
absorb
moisture
.
FOR
SAFETY
REASONS
,
STORE
THE
BREAKER
IN
THE
OPEN
POSITION
,
7
Courtesy of NationalSwitchgear.com

tr
1
.
PART
TWO
r
INSTALLATION
CONNECTIONS
Type
"
DB
"
circuit
breakers
are
furnished
as
complete
unit
assemblies
and
the
installation
con
-
sists
of
:
(
1
)
bolting
them
to
the
supporting
frame
-
work
or
structure
;
(
2
)
connecting
the
current
carry
-
ing
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
-
energize
the
load
and
control
leads
to
be
connected
,
and
also
the
section
of
the
switchboard
where
installation
is
being
made
.
Mounting
dimensions
and
details
of
the
front
en
-
closure
cutouts
are
shown
in
Figs
.
1
,
1
A
,
IB
,
and
1
C
.
To
prevent
distortion
of
the
breaker
panel
,
the
supporting
structure
should
be
checked
for
align
-
ment
.
Magnetic
material
in
the
mounting
structure
should
have
at
least
two
inches
clearance
to
the
breaker
studs
.
A
manual
closing
handle
is
supplied
with
each
order
of
DB
-
75
and
DB
-
100
breakers
.
This
handle
is
for
maintenance
only
and
in
no
case
should
it
be
used
for
closing
the
breaker
when
primary
circuit
is
energized
.
Typical
circuit
breaker
wiring
diagrams
are
shown
in
Fig
.
2
,
The
connecting
cables
or
bus
bars
should
have
adequate
current
carrying
capacity
,
or
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
.
ENCLOSURES
The
breaker
is
normally
mounted
in
the
enclosure
along
with
accompanying
bus
work
terminating
in
cable
clamps
.
Where
covers
are
mounted
on
en
-
closures
,
they
are
to
be
removed
and
drilled
to
provide
for
connecting
cable
,
All
connections
should
be
clean
,
smooth
and
free
from
burrs
to
assume
full
contact
area
.
They
should
be
firmly
clamped
or
bolted
in
place
to
prevent
excessive
heating
.
Cable
must
be
adequately
braced
to
withstand
full
short
circuit
currents
.
-
)
£
f
;
»
<
5
V
•
1
'
8
Courtesy of NationalSwitchgear.com

!
V
.
l
\
I
.
B
.
33
-
850
-
4
&
5
D
INSTALLATION
“
DB
”
AIR
CIRCUIT
BREAKERS
*
4
»
*
:
v
%
*
<
r
•
••
V
I
7
FIG
.
1
.
Type
DB
-
100
Air
Circuit
Breaker
,
Outline
and
Mounting
Dimensions
9
Courtesy of NationalSwitchgear.com

I
INSTALLATION
.
4
*
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FIG
.
1
A
.
Typo
DB
-
75
Air
Circuit
Breaker
.
Fixed
Outline
and
Mounting
Dimensions
10
Courtesy of NationalSwitchgear.com

t
I
.
B
.
33
-
850
-
4
&
5
D
INSTALLATION
.
“
DB
”
AIR
CIRCUIT
BREAKERS
V
--
/
•
h
!
4
FIG
.
IB
,
Type
DBF
-
40
Fixed
Outline
and
Mounting
Dimensions
ii
Courtesy of NationalSwitchgear.com

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Courtesy of NationalSwitchgear.com

II
H
LB
.
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600
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800
FIG
.
2
.
Typical
Wiring
Diagrams
Courtesy of NationalSwitchgear.com

!
f
1
(
PART
THREE
£
*
MAINTENANCE
POLE
UNIT
Each
,
pole
unit
(
Fig
.
3
)
is
mounted
on
a
separate
molded
base
.
The
molded
bases
are
attached
to
the
mounting
panel
and
provide
insulation
for
the
break
-
er
studs
.
The
upper
stud
and
contact
are
attached
to
the
molded
base
by
two
bolts
.
The
moving
contact
arm
is
pivoted
on
the
lower
stud
and
is
attached
to
the
cross
bar
through
an
insulating
link
.
The
lower
stud
is
fastened
to
the
molded
base
by
four
bolts
.
Contacts
.
(
See
Fig
.
3
.
)
The
arcing
contacts
must
touch
first
on
closing
and
open
last
on
opening
.
Do
not
adjust
one
set
of
contacts
without
check
-
ing
the
complete
sequence
of
all
poles
.
With
the
breaker
open
proceed
in
the
following
order
:
1
.
Turn
adjusting
nuts
(
A
)
on
insulating
link
to
vary
main
contact
pressure
.
Use
,
00
S
feeler
gauge
,
1
/
4
inch
wide
by
6
inches
long
,
inserted
as
shown
in
Fig
,
4
A
to
check
clearance
.
Feeler
(
X
)
above
contact
fingers
insures
that
they
have
all
been
deflected
.
Feeler
(
Y
)
inserted
below
fingers
insures
that
they
have
not
gone
solid
.
2
.
With
breaker
closed
and
latched
,
apply
pres
-
sure
on
each
stationary
V
^
rcing
contact
,
part
"
a
"
of
Fig
.
4
B
,
When
spring
is
fully
compressed
or
solid
,
clearance
from
moving
arcing
contact
(
b
)
should
be
'
/
32
to
Vs
inch
.
Adjust
by
turning
nuts
(
A
)
on
insulating
link
—
however
,
clearances
of
main
con
-
tacts
as
described
in
part
(
1
)
must
be
maintained
,
3
.
Check
the
above
adjustments
on
all
three
poles
.
After
all
poles
have
been
adjusted
and
with
one
set
of
arcing
tips
just
touching
,
the
clearance
between
the
other
two
sets
of
arcing
contacts
should
not
exceed
*
/
te
inch
.
Maintenance
of
Contacts
.
Rough
or
high
spots
should
be
removed
with
a
file
or
sandpaper
.
When
dressing
contacts
be
sure
to
protect
the
hinged
contact
of
all
poles
with
a
cloth
to
prevent
foreign
matter
from
lodging
in
the
hinged
contact
.
Cautions
All
power
must
be
removed
when
replacing
,
maintaining
or
adjusting
contacts
.
OPERATING
MECHANISM
The
operating
mechanism
(
Figs
.
3
-
3
A
)
is
non
-
ad
-
justable
and
consists
of
a
series
of
non
-
ferrous
links
designed
to
secure
low
closing
and
trippng
forces
.
To
check
for
friction
,
with
the
breaker
open
,
raise
trip
finger
and
slowly
lower
the
closing
handle
.
Release
trip
finger
and
slowly
raise
handle
.
The
linkage
should
follow
the
handle
without
sticking
and
a
"
click
"
will
be
heard
just
before
the
handle
reaches
the
full
up
position
.
To
remove
the
mechanism
proceed
as
follows
:
1
.
Remove
the
breaker
cross
bar
,
2
.
Loosen
the
outboard
bearings
at
the
ends
of
the
trip
bar
.
a
.
In
reassembly
,
tighten
bolts
holding
out
-
board
bearings
only
when
bearings
have
been
adjusted
to
prevent
any
binding
of
trip
shaft
.
3
.
Remove
the
tension
rods
between
the
mech
-
anism
and
aluminum
panel
.
4
.
Free
the
pin
(
1
-
3
)
*
from
the
moving
core
.
To
free
the
pin
,
first
remove
the
cotter
phi
from
the
spacer
on
the
right
side
of
the
pin
.
Partially
close
the
breaker
until
the
pin
lines
up
with
two
holes
in
the
sides
of
the
mechanism
frame
.
Hold
the
moving
core
up
,
and
then
drive
the
pin
to
the
right
just
far
enough
to
clear
the
moving
core
rod
.
Lower
the
moving
core
until
it
hits
its
stop
.
Drive
the
pin
to
the
left
into
its
original
position
.
5
.
Remove
the
four
mounting
bolts
.
•
'
ll
,
,
,
y
i
k
3
%
•
The
first
letter
or
number
refers
to
the
item
and
the
second
to
the
figure
number
.
(
Item
J
—
Fig
.
No
.
3
.
)
14
Courtesy of NationalSwitchgear.com

1
KB
.
33
-
8
S
0
-
4
&
5
D
INSTALLATION
"
DB
”
AIR
CIRCUIT
BREAKERS
t
4
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.
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J
V
FIG
,
3
.
Cross
-
Sectional
View
o
£
Air
Circuit
Breaker
15
Courtesy of NationalSwitchgear.com

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1.0
.
33
-
850
-
4
&
5
D
MAINTENANCE
,
“
DB
”
AIR
CIRCUIT
BREAKERS
FIG
,
4
.
Adjusting
Limits
of
Main
and
Arcing
Contacts
CLOSING
SOLENOID
a
.
Cautions
These
bolts
are
also
the
mounting
bolts
for
the
closing
solenoid
;
therefore
,
support
the
solenoid
while
remov
-
ing
the
bolts
.
6
.
Remove
the
mechanism
.
7
.
Before
assembling
mechanism
check
sliding
surfaces
of
two
latches
shown
at
UB
"
,
Fig
.
3
,
These
surfaces
must
be
clean
,
free
of
burrs
,
and
have
not
more
than
.
035
inch
clearance
in
the
reset
position
.
The
mechanism
is
factory
lubricated
for
life
.
The
closing
solenoid
(
Fig
.
5
)
is
non
-
adjustable
.
To
remove
the
close
coil
,
proceed
as
follows
:
1
.
Caution
:
Remove
the
close
coil
circuit
voltage
.
2
.
Disconnect
the
wires
from
the
close
coil
ter
-
minals
.
3
«
Loosen
the
locking
clip
(
4
)
on
the
bottom
of
the
moving
core
,
RECOMMENDED
CLOSING
FUSE
AMPERE
RATING
FUSE
CLOSING
COIL
7
/
*
BURDEN
1
'
NOMINAL
CONTROL
YOLTAGE
STYLE
NUMBER
CLOSING
AMPERES
TRIPPING
AMPERES
BREAKER
600
VOLT
250
VOLT
TYPE
Standard
Tima
Tima
Standard
NEC
Lag
NEC
Lag
All
48
DC
125
DC
250
.
DC
230
AC
460
AC
575
AC
DB
-
75
5
»
A
120
A
823
H
04
120
A
823
H
03
12
OA
023
HO
4
120
A
824
H
03
120
A
824
H
03
10
32
2
t
18
6
1
•
»
32
10
.
5
ii
6
.
2
18
«
t
6
.
3
15
24
DC
125
DC
250
DC
230
AC
460
AC
575
AC
115
AC
All
9.5
DB
-
100
DBF
-
40
•
•
i
4
»
120
A
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05
120
A
823
H
04
120
A
823
H
05
120
A
824
H
04
120
A
824
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04
15
32
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«
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1
10
18
*
•
32
.
5
15
18
.
2
10
15
.
3
10
1
JF
-
«
«
Note
:
For
A
-
C
closing
use
3
KVA
source
or
larger
17
•
'
•
'
v
.
Courtesy of NationalSwitchgear.com

MAINTENANCE
,
f
/
V
'
i
i
FIG
.
5
.
Closing
Solenoid
Construction
Details
The
various
ratings
of
each
general
type
are
of
similar
construction
and
differ
only
in
springs
and
calibration
,
The
overcurrent
tripping
device
can
be
removed
from
the
breaker
easily
and
replaced
with
another
unit
of
the
same
or
different
rating
without
affecting
the
calibration
of
the
units
involved
.
Construction
.
The
mounting
frame
casting
sup
-
ports
the
two
sub
-
assemblies
of
the
trip
unit
.
On
the
upper
part
of
the
frame
are
the
two
magnetic
armatures
and
their
associated
links
and
brackets
*
Fastened
to
the
lower
part
of
the
mounting
frame
is
the
moldarta
box
which
contains
the
calibration
springs
,
time
delay
elements
and
calibration
knobs
.
This
box
is
held
to
the
mounting
frame
by
two
long
screws
at
the
bottom
of
the
calibration
box
.
4
.
Remove
bolts
(
5
)
,
locking
clip
(
4
)
,
and
the
relay
trip
bracket
(
6
)
,
5
.
Remove
bolts
(
3
)
,
and
using
a
rawhide
or
plastic
mallet
remove
the
bottom
stationary
core
(
7
)
.
6
.
Remove
the
coil
.
7
.
After
assembling
coil
and
breaker
,
but
before
connecting
the
coil
,
ch
$
?
k
proper
co
-
ordination
between
breaker
closing
ahd
relay
tripping
.
Ener
-
gize
relay
operating
coil
only
(
Fig
,
11
)
,
and
manual
-
ly
close
breaker
very
slowly
.
The
relay
contacts
should
trip
free
slightly
before
the
position
at
which
the
mechanism
pawl
(
C
-
3
)
drops
in
the
latched
position
.
r y
I
i
OVERCURRENT
TRIPPING
DEVICE
Installation
and
Removal
Caution
:
Before
removing
or
installing
a
tripping
device
,
be
sure
that
the
breaker
is
in
the
open
position
and
de
-
energized
.
To
remove
an
overcurrent
tripping
device
from
the
breaker
,
loosen
the
two
bolts
at
the
bottom
of
the
mounting
frame
(
L
-
3
)
until
they
turn
freely
.
Description
.
The
overcurrent
tripping
device
(
Fig
.
6
)
,
for
the
circuit
breaker
is
an
air
delayed
magnetic
type
of
device
.
The
time
-
current
character
-
istics
of
the
trip
unit
are
as
follows
:
1
.
Long
delay
and
short
delay
.
2
.
Long
delay
and
instantaneous
.
3
.
Instantaneous
.
•.
’
I
'
<
•
.
18
Courtesy of NationalSwitchgear.com

KB
*
33
-
850
-
4
&
5
P
MAINTENANCE
“
DB
”
AIR
CIRCUIT
BREAKERS
Adjustment
of
Trip
Screw
.
The
trip
screw
mounted
on
the
trip
finger
must
be
adjusted
properly
to
obtain
proper
tripping
.
Cautions
Since
this
adjustment
involves
tripping
the
breaker
,
care
must
be
taken
to
keep
fingers
and
face
away
from
all
contact
arms
and
operating
linkage
.
To
proceed
with the
adjustment
,
turn
the
long
time
dial
at
the
bottom
of
the calibration box
counter
-
clockwise
to
the
stop
so
that
the
trip
unit is
set
for
minimum time
delay
.
Then close
the
breaker
and
carefully
reach
under
the
mechanism with
both
hands
and
push
the
lower
armature
fully
closed
with
the thumbs
.
Hold
it
closed
for
at
least
the
minimum
long
delay
time
(
20
to
40
seconds
)
.
If
the
breaker
trips
,
reset
the
screw
at
the
end
of
the
tripping
finger
until
the
breaker
just
barely
trips
.
Before
re
-
adjusting
the
trip
screw
,
make
sure
that
the
breaker
is
in
the
open
position
.
After
finding
the
position
of
the
trip
screw
at
which
the
breaker
Then
loosen the
two
bolts
at
the
top
of
the
mounting
frame
while
supporting
the
trip
unit
so
that
it
does
not
fall
.
These
two
bolts
clamp
a
slotted
angle
mounting
bracket
and
merely
have
to
be
loosened
;
they
do
not
have
to
be
removed
from
the
mounting
frame
.
The
trip
unit is
then
free
to
be removed
from
the breaker
by lowering
it
down
behind the
breaker
platform
.
To
install
a
tripping
device
on
a
breaker
,
first
make
certain
that
the breaker
is
open
and
is
not
connected
to
live
circuits
,
Then
loosen
the
upper
mounting
bolts
on
the
trip
unit
so
that
the bolts
can
slide
into
the
slotted
mounting
brackets
on
the
stationary
yoke
.
Then install the
trip
unit
from
the
bottom
of
the
breaker
,
sliding
it
up
behind
the
mechanism
platform
.
Start
the
bottom
two
mounting
bolts
,
but
do
not
tighten
completely
.
Next
,
align
the
trip
unit
so
that
the
gaps
between
the
tapered
portions
of
the
main
armature
are
approximately
equal
when
the
main
armature
is
closed
.
Then
tighten
all
four
mounting
bolts
securely
.
L
s
+
’
i
'
Xs
t
J
i
I
-
V
'
FIG
.
6
.
Cross
-
Sectional
View
of
Overcurrent
Tripping
Device with
Long
Delay
and
Instantaneous
Elements
19
Courtesy of NationalSwitchgear.com

•
I
MAINTENANCE
armature
(
B
)
to
be
attracted
toward
the
stationary
core
(
A
)
.
The
motion
of
the
armature
is
retarded
by
the
diaphragm
(
D
)
whose
motion
is
in
turn
controlled
by
the
amount
of
air
admitted
by
the
long
time
delay
valve
(
F
)
,
After
a
time
delay
,
determined
by
the
setting
of
valve
(
F
)
,
the
armature
will
have
rotated
the
trip
crank
(
J
)
far
enough
to
trip
the
breaker
by
moving
the
trip
lever
(
K
)
.
During
this
type
of
tripping
,
the
tension
spring
(
C
)
is
not
stressed
beyond
its
normal
length
.
On
larger
overload
currents
,
the
action
is
essen
-
tially
the
same
as
above
except
that
the
moving
armature
(
B
)
will
close
completely
as
soon
as
the
overload
is
applied
.
When
the
armature
closes
,
the
just
trips
,
turn
the
screw
exactly
one
full
turn
in
the
direction
to
trip
the
breaker
sooner
.
Check
to
make
sure
that
the
breaker
will
trip
when
either
armature
is
closed
if
long
and
instantaneous
type
trip
units
are
used
,
or
when
both
armatures
are
closed
if
long
and
short
delay
type
trip
units
are
used
.
The
short
delay
armature
is
for
timing
only
.
Closing
it
alone
will
,
not
trip
the
breaker
.
Operation
Standard
Overourrent
Tripping
Device
(
Ke
£
er
to
Fig
.
7
A
)
When
a
small
overload
current
flows
through
the
breaker
pole
unit
conductor
(
R
)
,
it
causes
the
moving
o
'
1
;
J
v
.
I
•
f
LEGEND
*
A
'
LONG
DELAY
STATIONARY
MAGNET
8
-
LONG
DELAY
MOVING
MAGNET
C
-
LONG
DELAY
FORCE
LIMITING
SPRING
D
-
DIAPHRAGM
E
-
AIR
CHAMBER
F
-
LONG
DELAY
VALVE
AND
DIAL
G
-
LONG
OELAY
PICK
-
UP
CALIBRATION
SPRING
H
-
RESET
VALVE
J
-
TRIP
CRANK
K
-
BREAKER
TRIP
FINGER
L
-
INSTANTANEOUS
STATIONARY
MAGNET
M
-
INSTANTANEOUS
MOVING
MAGNET
Q
-
INSTANTANEOUS
PICK
-
UP
CALIBRATION
SPRING
R
-
BREAKER
MOVING
CONTACT
ARM
W
-
SHAFT
GUIDE
BEARING
1
SOLID
JOINT
+
PINNED
JOINT
-
j
-
NO
JOINT
STOP
SURFACE
1
i
it
A
y
3
i
I
s
LONG
DELAY
PICK
-
UP
ADJUSTMENT
\
M
I
\
\
\
-
TOTAL
CLEARING
TIME
V
V
-
\
V
\
*
“
/
rim
"
s
It
N
I
5
\
LONG
DELAY
TIME
ADJUSTMENT
*
1 1
r
>
/
/
t
/
/
/
If
/
,
w
i
-
OK
J
\
r
p
f
RESETTABLE
DELAY
l
f
V
J
I
J
-
!
t
\
5
,
!
f
-
J
If
lli
w
o
INSTANTANEOUS
PICK
-
UP
ADJUSTMENT
UJ
3
\
N
i
»
P
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i
!
V
i
!
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d
I
1
i
i
0
I
I
\
11
s
i
l
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i
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I
V
I
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!
i
ADJUSTABLE
SCHEMATIC
DIAGRAM
CURRENT
MAGNITUDE
FIGURE
7
A
TYPICAL
TRIPPING
CHARACTERISTICS
FIGURE
78
•
-
FIG
.
7
.
Schematic
and
Typical
Time
-
Current
Characteristics
of
Overcurrent
Tripping
Device
with
Long
Delay
and
Instantaneous
Elements
V
20
Courtesy of NationalSwitchgear.com