Westinghouse De-ion 50-DH-350 User manual

I
.
B
.
32
-
251
-
4
OPERATION
RECEIVING
MAINTENANCE
INSTRUCTIONS
AIR
CIRCUIT
BREAKER
Type
50
DH
350
Horizontal
Drawout
Indoor
and
Ontdoor
Service
INTERRUPTING
RATINGS
—
AMPERES
VOLTAGE
RATINGS
3
-
PHASE
INTER
-
RUPTING
RATING
AMPERES
CONTIN
-
A
1
R
CIRCUIT
BREAKER
Min
.
KV
.
for
Rated
uous
Max
.
Design
At
60
CYCLES
TYPE
MVA
.
Rated
Rated
Max
.
Amperes
INT
.
KV
.
KV
.
Voltage
MVA
.
4.76
4.0
50
,
000
50
,
000
50
-
DH
-
350
50
-
DH
-
350
350
4.16
1200
48
,
000
48
,
000
4.0
4.16
4.76
3000
350
WESTING
HOUSE
ELECTRIC
CORPORATION
SWITCHGEAR
APPARATUS
DEPARTMENTS
EAST
PITTSBURGH
,
PA
.
NOVEMBER
,
1958
EAST
PITTSBURGH
PLANT
NEW
INFORMATION
Printed
in
U
.
S
.
A
.
Courtesy of NationalSwitchgear.com

1
TABLE
OF
CONTENTS
DESCRIPTION
Part
One
Pages
5
-
6
Description
5
RECEIVING
,
HANDLING
AND
STORING
Part
Two
Page
7
Receiving
Handling
.
Storing
. . .
7
7
7
OPERATION
Part
Three
Pages
8
to
18
Operation
Mechanism
Mechanism
Panel
Shunt
Trip
Magnet
Cut
-
Off
Switch
Contact
Position
Indicator
Interlock Position
Indicator
Operation
Counter
Auxiliary
Switch
Latch
Check Switch
Undervoltage
Trip
Attachment
Three
-
Coil
Trip
Attachment
...
Contacts
Arc
Chutes
Levering
-
In
Device
Test
Position
Operating
Position
Interlock
Secondary
Contacts
Puffer
Assembly
Arc
Chute
Lifter
8
8
10
10
10
10
10
10
11
11
11
11
11
11
15
15
15
16
16
17
18
INSTALLATION
Pari
FOOT
Pages
19
-
20
Installation
19
i
ADJUSTMENT
Part
Five
Page
21
Mechanism
Tripping
Latch
Cut
-
Off
Switch
Latch
Check
Switch
Contacts
21
21
21
21
21
2
Courtesy of NationalSwitchgear.com

1
I
.
B
.
32
-
251
-
4
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
TABLE
OF
CONTENTS
—
Continued
MAINTENANCE
Pages
22
-
27
Part
Six
22
Maintenance
Contacts
Moving
Contact
Assembly
Stationary
Main
Contact
Stationary
Arcing
Contacts
Arc
Chutes
Broken
or
Cracked
Ceramic
Parts
Erosion
of
Ceramics
Dirt
in
Arc
Chute
Cleaning
Arc
Shields
Operating
Mechanism
Lubrication
Clearances
Puffer
Puffer
Nozzle
Organic
Insulation
22
22
25
25
25
.
25
25
<
25
26
26
1
26
26
27
27
27
PARTS
IDENTIFICATION
Page
28
Part
Seven
28
Parts
Identification
Renewal
Parts
28
i
4
4
I
3
Courtesy of NationalSwitchgear.com

LIST
OF
ILLUSTRATIONS
Figure
Page
1
Type
50
-
DH
-
350
,
3000
Amp
.
,
Breaker
Completely
Assembled
2
Type
50
-
DH
-
350
,
3000
Amp
.
Breaker
with
Barrier
Removed
.
.
3
Breaker
with
Barrier
Removed
and
Arc
Chutes
Tilted
Back
for
Inspection
.
7
4
Solenoid
Operating
Mechanism
5
Mechanism
Panel
6
Moving
Contact
Assembly
7
Stationary
Contact
Assembly
8
Arc
Chute
Arrangement
9
Partially
Assembled
Arc
Chute
10
View
of
Lower
Part
of
Breaker
from
Rear
11
Rear
View
of
3000
Amp
.
,
50
-
DH
-
350
Breaker
12
Rear
View
of
1200
Amp
.
,
50
-
DH
-
350
Breaker
13
Front
View
Showing
Socket
for
Operating
Secondary
Contacts
14
Method
of
Operating
Secondary
Contacts
15
Pole
Unit
Assembly
16
Moving
Contact
Assembly
17
Stationary
Contact
Assembly
18
Puffer
Assembly
5
6
9
I
10
12
13
14
15
16
17
17
17
18
18
23
24
27
4
Courtesy of NationalSwitchgear.com

I
.
B
.
32
-
251
-
4
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
PART
ONE
DESCRIPTION
Minimum
voltage
for
rated
interrupting
capacity
Interrupting
current
at
rated
voltage
Maximum
interrupting
current
....
50
,
000
Amps
Figure
1
shows
a
50
-
DH
-
350
breaker
completely
assembled
.
Figure
2
shows
the
same
breaker
with
the
main
barrier
removed
.
This
shows
the
arrange
-
ment
of
the
center
-
coil
arc
chutes
,
separating
con
-
tacts
,
primary
disconnecting
contacts
,
insulated
operating
rods
,
and
the
solenoid
operating
mech
-
anism
.
These
components
are
supported
on
a
welded
steel
frame
which
is
mounted
on
flanged
wheels
for
rolling
into
the
metal
-
clad
cell
.
In
the
lower
part
of
the
frame
is
located
the
levering
-
in
device
for
moving
the
breaker
into
final
contact
engagement
.
It
is
interlocked
with
the
mecha
-
nism
to
prevent
inserting
or
withdrawing
the
breaker
with
the
contacts
closed
.
It
also
prevents
closing
the
contacts
unless
the
breaker
is
completely
in
or
completely
out
of
the
cell
.
Also
located
in
the
lower
part
of
the
frame
are
the
secondary
contacts
,
for
automatically
disconnecting
the
control
wiring
when
the
breaker
is
in
the
withdrawn
position
,
the
auxiliary
switch
,
shunt
trip
,
cut
-
off
switch
,
latch
checking
switch
,
operation
counter
,
breaker
con
-
tacts
position
indicator
,
and
levering
-
in
device
position
indicator
.
The
arc
chutes
on
this
breaker
are
of
the
center
-
coil
design
.
With
this
type
of
construction
,
the
magnetic
circuit
is
H
-
shaped
with
the
cross
member
of
the
H
passing
through
the
center
of
the
arc
chute
.
The
blowout
coils
are
wound
around
the
cross
member
of
the
H
and
lie
in
the
center
of
the
arc
chute
.
With
this
arrangement
,
the
magnet
core
passing
through
the
center
of
the
arc
chute
,
it
is
impossible
to
remove
the
arc
chute
from
the
magnet
.
To
pro
-
vide
easy
accessibility
for
contact
maintenance
and
inspection
,
the
arc
chutes
are
hinged
at
the
rear
,
and
a
simple
tilting
device
is
provided
.
Figure
3
shows
the
breaker
with
the
arc
chutes
tilted
back
.
The
levering
-
in
device
is
used
to
supply
the
me
-
chanical
advantage
for
tilting
the
arc
chutes
.
A
one
piece
barrier
assembly
is
placed
on
the
breaker
before
it
is
rolled
into
the
cell
.
The
front
sheet
is
of
1
/
g
-
inch
aluminum
to
form
a
grounded
barrier
between
personnel
and
live
parts
when
the
unit
is
in
the
cell
.
4.0
KV
48
,
000
Amps
<
)
FIG
.
1
.
Type
59
-
DH
-
350
,
3000
Amp
.
,
Breaker
Completely
Assembled
The
type
50
-
DH
-
350
air
circuit
breaker
is
a
three
-
pole
,
electrically
operated
,
horizontal
draw
-
out
unit
for
metal
-
clad
switchgear
.
The
rating
of
the
breaker
is
as
follows
:
350
MVA
Interrupting
rating
Continuous
current
at
60
cycles
Rated
voltage
Maximum
design
voltage
1200
&
3000
Amps
4.16
KV
4.76
KV
5
Courtesy of NationalSwitchgear.com

Description
FIG
.
2
.
Type
50
-
DH
-
350
,
3000
Amp
.
,
Breaker with Barrier
Removed
.
The
50
-
DH
-
350
air
circuit
breaker
is
arranged
for
use
in
metal
-
clad
equipment
from
which
it
is
drawn
out
horizontally
.
As
may
be
seen
in
Fig
.
2
,
all
parts
are
supported
on
a
steel
frame
with
four
wheels
,
with
roller
bearings
,
to
facilitate
moving
the breaker
.
The wheel
flanges
engage
with the
rails
to
align
the
breaker
in
the
cell
.
The
main
conductors
project
horizontally
from
the
rear
of
the
breaker
,
and
are
supported
and
insulated
by
Redarta
condenser
bushings
.
On
the
ends
of
these
main
conductors
are
clusters
of
finger
contacts
arranged
to
engage
the
primary
conductors
in
the
cell
.
6
Courtesy of NationalSwitchgear.com

PART
TWO
I
.
B
.
32
-
251
-
4
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
i
4
4
FIG
.
3
.
Breaker with Barrier Removed and
Arc
Chutes
Tilted
Back
for
Inspection
RECEIVING
,
HANDLING
,
STORING
The
type
50
-
DH
-
350
breaker
is
assembled
and
given
operating
tests
at
the
factory
.
Then
it
is
care
-
fully
inspected
and
prepared
for
shipment
by
workmen
experienced
in
the
proper
handling
and
packing
of
electrical
equipment
.
In
order
to
afford
maximum
protection
against
damage
,
the
main
bar
-
rier
assembly
and
the
arc
chutes
are
packed
sep
-
arately
.
For
each
three
-
pole
breaker there
is
one
barrier
assembly
and
three
arc
chutes
.
After
the
equipment
has
been
unpacked
,
make
a
careful
inspection
for
any
damage
which
may
have occurred
in
transit
.
If
the
apparatus
has
been
damaged
,
file
a
claim
immediately
with the
carrier
and
notify
the
nearest
Westinghouse
Sales Office
.
The
base
of
the
crate
may
be used
as
a
skid
for
moving
the breaker
,
or
the breaker
may
be
lifted
with
slings
under
the
crate
.
If
the
breaker
is
to
be
lifted with
slings
,
move
it
while
it
is
still crated
.
After
the breaker
is
unpacked
the
best
way
to
move
it
is
by rolling
it
on
its
own
wheels
.
If
it
is
necessary
to
lift
the
breaker
after
it
is
incrated
,
lift
it
without the
barrier
or arc
chutes
in
place
.
Slings
may
be
placed
under the breaker
frame
or
hooks used
in
the
holes
provided
in
the
frame
.
«
STORING
The
arcing
chambers
are
shipped
in
separate
containers
to
guard
against
damage
from
rough
handling
and
for
better
protection
from
dust
and
water
or
liquids
.
Store
them
in
their
shipping
con
-
tainers
until
ready
for
use
.
Store
all
components
of
these
breakers
in
a
clean
dry
place
.
During
the
storage
period
,
keep
them
sufficiently
warm
to
prevent
moisture
con
-
densation
.
HANDLING
Remove
the
crating
and
packing carefully
.
To
avoid
damage
from
negligent handling
of
crow
-
bars
or
other tools
,
use
a
nail
puller
for
the
un
-
crating
.
Care
must
be used
in
handling
the
arc
chutes
since
the
splitter plates
in
them
are
made
of
a
ceramic
material which
may
break
if
dropped
.
7
Courtesy of NationalSwitchgear.com

PART
THREE
The
approximate
weight
of
the
breaker and
the
various
breaker
parts
is
given
below
:
BREAKER
PARTS
1
,
200
AMPS
.
3
,
000
AMPS
.
Breaker without
arc
chutes
and
barrier
Single
arc
chute
Barrier
assembly
Complete
breaker
2
,
025
pounds
238
pounds
84
pounds
2
,
823
pounds
2
,
300
pounds
238
pounds
84
pounds
3
,
098
pounds
4
OPERATION
four
(
4
)
major
links
:
the
non
-
trip
free
lever
,
trip
free
lever
,
upper
trip
free
link
,
and lower
trip
free
link
.
These
members
are
arranged
as
shown and
are
held
to
form
a
rigid
member
by
the
cam
link
and
tripping
cam
.
The
tripping
cam
is
held fixed
by
the
tripping
latch
.
When
the solenoid
is
energized
,
it
pulls
on
the
junction
of
the
non
-
trip
free
lever and the
lower
trip
free
link
,
causing
the
system
to rotate
about
the
operating
center
.
The
trip
free
lever then
exerts
an
upward
force
on
the
operating
rods
to
close
the
breaker
.
The breaker
is
held
in
this
position
by
the
closing
latch
.
The breaker
is
tripped
electrically
or
manually
by
lifting
the
trigger
which
disengages
the
primary
latch
.
This allows the
tripping
latch
to
release the
tripping
cam so
that
it
is
free
to rotate
.
Without
the
restraining
force of
the
cam
and
cam
links
,
the
major
linkage
collapses
under
the
force of
the
contact
springs
,
the
springs
in
the
air
bumpers
,
and
the
accellerating
springs
over
the
puffer
rods
.
The
junction
of
the
upper
and lower
trip
free
links
moves
to
the
right
,
and the
trip
free
lever
rotates
clock
-
wise
opening
the
breaker
.
The
position
of
the
link
-
age
is
then
as
shown
in
Fig
.
4
B
.
In
moving
to
this
position
,
the lower
trip
free
link
has
disengaged
the
closing
latch
.
The
re
-
trieving
springs
now
pull
on
the
solenoid
core
which
moves
the
linkage
to
the
reset
position
as
shown
in
Fig
.
4
C
.
In
this
position
the
tripping
latch
is
reset
and the breaker
may
be reclosed
.
Before
placing
the
circuit
breaker
in
service
,
it
is
advantageous
to
become
familiar
with the
con
-
struction
and function
of
the
various
parts
.
The
following
paragraphs
describe
the
operation
of
the
various
breaker
parts
.
This material should
be
studied
carefully
before
placing
the breaker
in
service
.
The
general
arrangement
of
the
breaker
com
-
ponents
is
shown
in
Fig
.
2
.
The
solenoid
coil
is
built
to
exert
a
horizontal
force
on
the
mechanically
trip
free
linkage
.
This
linkage
,
in
turn
,
exerts
an
upward
force
on
the
pole
unit
insulated
operating
rods
which
act
on
the
moving
contact
arms
to
open
and close
the
contacts
.
The breaker
has three
sets
of
contacts
;
main
,
intermediate
,
and
arcing
.
On
opening
,
these
contacts
separate
in
the
order
named
;
on
closing
,
they
touch
in
the
reverse
order
.
On
the
outer
ends
of
the condenser
bushings
are
clusters
of
finger
contacts
for
engaging
the
main
circuit
contacts
in
the cell
.
Above
the
arcing
contacts
are
located
the
center
-
coil
arc
chutes
.
The
breaker
is
tripped
by
lifting
the
primary
latch
either
manually
or
electrically by
means
of
the
trip
coil
.
*
4
MECHANISM
The
solenoid
operating
mechanism
with
its
trip
-
free
linkage
is
shown
in
Fig
.
4
.
In
this
mechanism
,
the
horizontal
pull
of
the solenoid
coil
is
transmitted
to
the
contact
operating
rods
through
a
system
of
links
which
rotate
counterclockwise
about
the
operating
center
.
The
linkage
system
consists
of
8
Courtesy of NationalSwitchgear.com

I
SUPPLEMENT
TO
INSTRUCTION
BOOKS
I
.
B
.
32
-
251
-
3
Deion
Air
Circuit
Breaker
Type
DH
I
.
B
.
32
-
251
-
4
Deion
Air
Circuit
Breaker
Type
50
-
DH
-
350
I
.
B
.
32
-
251
-
6
Deion
Air
Circuit
Breaker
Type
150
-
DH
-
1000
I
.
B
.
32
-
251
-
9
A
Motor
Operated
Stored
Energy
(
Spring
)
Closing
Mechanism
Type
SE
-
2
The
circuit
breakers
and
the
mechanism
covered
by
the
above
instruction
books
contain
a
mechanism
for
tripping
(
opening
)
the
breaker
by
hand
.
The
circuit
breakers
provided
with
stored
energy
(
spring
)
closing
in
addition
to
hand
trip
contain
also
a
hand
spring
release
(
hand
close
)
.
Each
of
these
hand
tripping
respectively
closing
mechanisms
includes
two
rollers
,
one
engaging
with
the
"
tripping
cam
"
and
one
engaging
with
the
"
primary
latch
"
.
The
parts
are
shown
in
the
illustrations
as
follows
:
Figure
6
-
A
Figure
4
-
A
Figure
5
-
A
Figure
9
and
Figure
13
respectively
Page
10
Page
9
Page
11
Page
9
Page
13
I
.
B
.
32
-
251
-
3
I
.
B
.
32
-
251
-
4
I
.
B
.
32
-
251
-
6
I
.
B
.
32
-
251
-
9
A
The
rollers
rotate
on
corresponding
pins
and
for
trouble
-
free
operation
of
the
breakers
must
rotate
very
freely
without
any
friction
or
dragging
.
To
insure
this
,
the
rollers
and
pins
must
be
lubricated
approximately
once
every
year
or
every
2000
operations
.
The
recommended
lubricant
is
Westinghouse
material
8577
-
2
,
supplied
by
Westinghouse
Electric
Corporation
,
Benolite
Department
,
Manor
,
Pa
.
,
as
"
Lubricant
B
-
7
-
216
"
.
Application
of
lubricants
is
to
be
made
on
breaker
open
and
with
the
spring
discharged
(
in
case
of
breakers
provided
with
stored
energy
closing
mechanism
)
,
as
follows
:
Apply
a
few
drops
of
lubricant
on
each
side
of
roller
.
Hold
the
primary
latch
(
hand
trigger
)
up
;
then
lift
the
rollers
up
,
one
after
another
,
and
rotate
them
to
distribute
the
lubricant
over
the
pin
.
After
the
solvent
has
evaporated
,
repeat
the
process
once
or
twice
more
.
Courtesy of NationalSwitchgear.com

I
.
B
.
32
-
251
-
4
Operation
,
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
)
i
*
i
9
-
»
i
FIG
.
4
.
Solenoid
Operating
Mechanism
9
Courtesy of NationalSwitchgear.com

OPERATION
.
•
MECHANISM
STOP BOLT
9
POLE
AUX
.
SWITCH
TRIP
CUT
-
OFF
SWITCH
LEVER
LEVERING
-
IN
DEVICE
OPERATING
SHAFT
BARRIER
MOUNTING
BRACKET
OPERATION
COUNTER
INTERLOCK
POSITION
INDICATOR
1
LATCH CHECK
SWITCH
CONTACT
POSITION
'
INDICATOR
FIG
.
5
.
Mechanism
Panel
MECHANISM
PANEL
Contact
Position
Indicator
.
The
contact
position
indicator
gives
a
positive
indication
that
the
breaker
contacts
are
either
open
or
closed
.
It
operates
directly
on
the
trip
-
free
lever
in
the
mechanism
.
Interlock
Position
Indicator
.
The interlock
position
indicator
gives
a
positive
indication
of
the
position
of
the
breaker interlock
.
It
operates
off
the
levering
-
in
device shaft
.
When
the
indicator
points
to
the
word
OPERATE
,
the
interlock
is
free
and the
breaker
may
be closed
or
tripped
.
When
the
indi
-
cator
points
to
the
word
INTERLOCKED
,
the
inter
-
lock
is
functioning
and the breaker
cannot
be
closed
.
Since
the interlock
is
operative
only
when
the
breaker
is
in
an
intermediate
position
between
fully
engaged
and
fully
withdrawn
,
it
also
serves
as
a
means
of
indicating
when the
breaker
is
all
the
way
in
or
all
the
way
out
of
the
cell
.
Operation
Counter
.
The
operation
counter
records each
operation
of
the
breaker
.
It
advances
one
count
of
each
tripping
operation
.
A
link
to
the
trip
free
lever
operates
the
counter
.
The
mechanism
panel
is
mounted
on
the
front
of
the
closing
mechanism
as
shown
in
Fig
.
5
.
On
it
are
mounted the
following
auxiliary
devices
included
as
standard
on
all
breakers
.
Shunt
Trip
Magnet
.
The shunt
trip
magnet
is
a
small
electromagnet
which
is
used
to
trip
the
breaker
electrically
.
It
may
be
equipped
with
a
coil
for
direct
current
,
alternating
current
,
or
capacitor
tripping
.
When
the
shunt
trip
magnet
is
energized
,
the
core
is
drawn
up
into
the
magnet
yoke
.
An
extension
of
the
core
protrudes
through
the
top
of
the
magnet
assembly
.
As
the
core moves
up
,
this
extension
moves
up
against
the
trip
lever
directly
above
it
.
The
force of
the
solenoid
is
sufficient
to
raise
the
trip
lever
which
disengages
the
primary
latch
tripping
the breaker
.
Cut
-
Off
Switch
.
The
cut
-
off
switch
is
an
"
AA
"
contact
which
acts
with the
breaker control
relays
to cut
off
the
closing
coil
current
after
the breaker
is
closed
.
The
switch
is
operated
by
an
arm
at
-
tached
to
the
trip
-
free
lever
in
the mechanism
.
*
10
Courtesy of NationalSwitchgear.com

I
.
B
.
32
-
251
-
4
OPERATION
.
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
Auxiliary
Switch
.
The
auxiliary
switch
is
a
9
-
pole
rotary
type
switch
which
is
operated
by
a
link
from
the
trip
free
lever
in
the
mechanism
.
Latch
Check
Switch
.
The
latch
check
switch
is
a
small
,
light
force
,
snap
action
switch
which
is
operated
by
the
primary
latch
.
When
a
breaker
is
to
be
automatically
reclosed
after
being
tripped
free
,
it
is
necessary
to
arrange
the
electrical
con
-
trol
scheme
so
that
the
closing
solenoid
will
not
be
energized
to
start
the
closing
motion
until
the
mechanism
has
completed
the
linkage
motion
to
get
to
the
reset
position
.
See
B
and
C
of
Fig
.
4
.
For
this
purpose
,
the
switch
is
arranged
to
be
closed
when
the
primary
latch
is
reset
,
because
the
primary
latch
is
the
last
part
to
reset
in
the
sequence
of
linkage
motions
required
to
reset
the
mechanism
.
In
addition
to
the
above
items
which
are
standard
on
all
breakers
,
the
following
special
devices
may
also
be
mounted
on
the
mechanism
panel
when
required
.
Under
voltage
Trip
Attachment
.
The
under
-
voltage
trip
attachment
is
a
magnetically
held
device
which
will
trip
the
breaker
using
the
force
stored
in
a
spring
during
the
breaker
closing
stroke
when
the
control
voltage
drops
below
a
predetermined
value
.
For
instantaneous
release
,
the
holding
magnet
coil
may
be
directly
connected
to
a
d
-
c
control
source
,
or
it
may
be
supplied
with
low
voltage
d
-
c
obtained
from
an
a
-
c
control
volt
-
age
through
a
small
transformer
and
rectox
as
-
sembly
mounted
in
the
cell
structure
.
For
time
delay
-
ed
release
,
a
special
very
high
resistance
coil
is
used
in
the
holding
magnet
.
It
is
supplied
with
d
-
c
voltage
from
a
transformer
,
rectox
,
and
capacitor
assembly
mounted
in
the
cell
.
The
capacitor
is
con
-
nected
across
the
coil
and
provides
a
slowly
decay
-
ing
holding
current
.
The
holding
magnet
is
mounted
on
the
mechanism
panel
to
the
right
of
the
shunt
trip
magnet
.
Three
-
Coil
Trip
Attachment
.
The
three
-
coil
trip
attachment
,
when
supplied
,
mounts
on
the
mechanism
panel
and
is
used
in
addition
to
the
shunt
trip
magnet
.
It
is
designed
to
accommodate
three
instantaneous
current
transformer
trip
as
-
semblies
.
The
calibration
on
each
of
the
current
trip
coils
is
engraved
with
the
values
of
current
required
to
trip
the
breaker
.
The
moving
contact
is
a
copper
casting
to
which
are
brazed
the
arcing
,
secondary
,
and
main
con
-
tact
inlays
.
It
is
bolted
between
4
formed
copper
blades
which
hinge
on
the
lower
bushing
foot
and
form
the
moving
contact
arm
.
See
Fig
.
6
,
All
the
contact
resiliance
is
built
into
the
sta
-
tionary
contact
assembly
.
Because
of
the
high
momentary
rating
of
the
breaker
,
the
contacts
have
been
divided
to
give
a
multiplicity
of
contact
sur
-
faces
.
See
Fig
.
7
.
Three
sets
of
arcing
and
secondary
contacts
are
brazed
to
castings
which
are
mounted
over
pins
and
biased
by
springs
in
the
center
of
the
stationary
contact
assembly
.
On
each
side
of
the
arcing
and
secondary
contacts
are
five
main
contact
fingers
.
They
are
held
in
place
and
biased
by
the
springs
which
are
over
the
studs
which
pass
through
the
fingers
.
This
arrangement
of
the
contacts
,
a
relatively
long
and
narrow
arrangement
,
permits
all
the
contacts
to
be
up
inside
the
arc
chutes
.
\
%
«
ARC
CHUTES
The
arc
chute
consists
of
an
H
-
shaped
blow
-
out
magnet
,
blow
-
out
coils
,
transfer
arc
horns
,
transfer
stacks
,
main
interrupter
stacks
,
a
front
arc
horn
,
and
a
rear
arc
horn
all
assembled
in
and
about
a
fabricated
rectangular
Redarta
chute
jacket
.
The
arc
chute
is
hinged
to
the
breaker
;
and
when
it
is
in
the
normal
position
,
its
lower
end
completely
surrounds
the
contact
structure
.
Figure
8
is
a
schematic
cross
section
of
the
arc
chute
showing
the
component
parts
.
The
blow
-
out
magnet
is
located
so
that
the
core
passes
through
the
center
of
the
arc
chute
.
The
blow
-
out
coils
are
wound
about
the
core
and
lie
in
windows
cut
in
the
chute
jacket
side
sheets
.
One
terminal
of
each
coil
connects
to
a
transfer
arc
horn
,
and
the
other
terminals
are
joined
together
with
the
shading
coil
.
Two
transfer
stacks
are
placed
in
the
space
between
the
transfer
arc
horns
and
the
shading
coil
.
To
either
side
of
the
transfer
arc
horns
are
the
main
interrupter
stacks
which
are
made
up
of
a
series
of
insulating
refractory
plates
.
These
plates
have
inverted
V
-
shaped
slots
molded
into
them
.
The
slots
are
offset
so
that
when
the
plates
are
stacked
with
the
slots
alternating
from
one
side
to
the
other
,
the
arc
must
take
a
serpentine
path
as
it
moves
up
into
the
arc
chute
increasing
the
length
of
the
arc
.
To
either
side
of
the
main
interrupter
stacks
are
two
metallic
arc
horns
to
which
the
arc
transfers
from
the
arcing
contacts
.
The
front
arc
horn
is
>
*
*
CONTACTS
The
50
-
DH
-
350
breaker
is
equipped
with
3
sets
of
contacts
;
main
,
intermediate
,
and
arcing
.
When
the
breaker
is
tripped
,
the
contacts
separate
in
the
order
named
above
;
and
when
the
breaker
is
closed
,
they
make
up
in
the
reverse
order
.
I
ii
Courtesy of NationalSwitchgear.com

OPERATION
,
1
1
4
FIG
.
6
.
Moving
Contact
Assembly
Courtesy of NationalSwitchgear.com

I
.
B
.
32
-
251
-
4
OPERATION
,
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
Courtesy of NationalSwitchgear.com

OPERATION
.
contact
.
contacts
part
and
an
arc
is
drawn
,
it
loops
up
and
14
Courtesy of NationalSwitchgear.com

I
.
B
.
32
-
251
-
4
Operation
,
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
breaker
,
push
in
,
and
rotate
to
engage
the
coupling
in
the
levering
-
in
device
.
The
breaker
contacts
must
be
open
to
engage
the
coupling
.
Rotate
the
crank
counterclockwise
to
the
end
of
the
travel
.
At
the
end
of
the
travel
,
the
interlock
will
release
,
the
handle
will
move
back
out
,
and
the
indicator
on
the
mechanism
panel
will
point
to
the
word
OPERATE
.
With
the
levers
to
the
rear
and
down
as
shown
in
Fig
.
11
,
the
breaker
is
ready
to
be
rolled
into
the
cell
as
far
as
the
test
position
.
The
rollers
on
the
levers
strike
vertical
angles
on
the
cell
wall
and
stop
the
breaker
at
the
test
position
.
If
the
breaker
is
to
be
operated
at
this
position
,
remove
the
crank
and
engage
the
secondary
contacts
in
the
manner
described
in
the
section
under
Secondary
Con
-
tacts
.
To
move
the
breaker
from
the
test
position
to
the
fully
engaged
operating
position
,
put
the
crank
on
the
shaft
,
push
in
and
rotate
to
engage
the
levering
-
in
coupling
,
and
crank
clockwise
.
The
torque
required
will
increase
slightly
when
the
primary
contact
fingers
engage
the
studs
in
the
cell
.
Continue
cranking
to
the
end
of
the
travel
where
the
interlock
will
again
fall
free
pushing
the
crank
back
out
.
Remove
the
crank
.
The
indicator
on
the
panel
will
again
point
to
the
word
OPERATE
.
To
remove
the
breaker
from
the
operating
posi
-
tion
,
first
check
that
the
breaker
is
open
.
The
levering
-
in
device
can
not
be
engaged
unless
the
breaker
contacts
are
open
.
Put
the
crank
on
the
operating
shaft
,
push
in
and
rotate
to
engage
,
and
turn
counterclockwise
until
the
breaker
returns
to
the
test
position
.
Remove
the
crank
.
Caution
:
Never
move
the
breaker
beyond
the
test
position
unless
the
arc
chutes
and
barrier
are
in
position
.
FIG
.
9
.
Partially
Assembled
Arc
Chute
impinges
on
the
lower
ends
of
the
two
transfer
arc
horns
and
the
shading
coil
.
The
two
short
seg
-
ments
of
the
arc
move
from
the
transfer
arc
horns
to
the
shading
coil
,
then
move
up
into
the
transfer
stacks
and
are
quickly
interrupted
placing
the
blow
-
out
coil
in
series
with
the
arc
.
When
the
current
starts
to
flow
in
the
blow
-
out
coils
,
a
magnetic
field
is
established
and
the
arc
,
which
by
this
time
is
two
separate
arcs
extending
from
the
two
end
arc
horns
to
the
transfer
horns
,
is
driven
very
rapidly
into
the
slots
of
the
refractory
plates
.
As
the
arc
moves
to
the
closed
end
of
the
slots
,
it
is
restricted
,
lengthened
,
cooled
,
and
sub
-
ject
to
a
strong
magneticly
induced
blast
of
gas
.
All
of
these
forces
result
in
rapid
deionization
of
the
arc
space
;
and
for
the
arc
to
maintain
itself
,
it
must
continuously
ionize
fresh
gas
.
At
current
zero
the
formation
of
new
ionization
momentarily
ceases
,
but
the
de
-
ionization
continues
so
that
dielectric
strength
is
established
in
the
arc
space
and
the
circuit
is
interrupted
.
Figure
9
is
a
photograph
of
a
partly
assembled
arc
chute
.
i
t
LEVERING
-
IN
DEVICE
In
order
to
move
the
breaker
in
or
out
of
the
cell
against
the
resistance
of
the
contact
fingers
,
a
levering
-
in
device
is
provided
on
each
breaker
.
There
is
a
lever
on
each
side
mounted
on
a
com
-
mon
shaft
across
the
back
of
the
breaker
.
On
each
lever
is
a
roller
which
engages
a
groove
in
the
sidewall
of
the
cell
.
A
removable
crank
engages
another
shaft
in
the
right
front
corner
of
the
breaker
which
turns
the
levers
through
the
worm
gear
arrangement
.
Before
a
breaker
is
rolled
into
a
cell
,
the
levers
,
with
rollers
,
at
each
side
of
the
breaker
must
point
to
the
rear
and
slightly
downward
as
shown
in
Fig
.
11
.
The
position
of
the
levers
shown
in
Fig
.
12
is
that
which
they
take
after
the
breaker
is
cranked
into
the
operating
position
.
To
put
the
levers
in
the
position
shown
in
Fig
.
11
,
place
the
crank
on
the
operating
shaft
at
the
front
right
comer
of
the
TEST
POSITION
When
the
breaker
is
first
moved
into
the
metal
clad
cell
,
it
moves
until
the
rollers
on
the
levering
-
in
device
come
up
against
a
pair
of
vertical
angles
welded
into
the
cell
.
This
is
the
test
position
.
In
this
position
,
the
breaker
primary
contacts
are
separated
from
the
energized
contacts
in
the
cell
,
and
a
metal
shutter
is
closed
completely
isolating
all
live
parts
from
the
breaker
.
The
secondary
contacts
may
be
engaged
and
the
breaker
operated
safely
without
the
arc
chutes
or
barriers
.
Caution
:
The
breaker
should
never
be
moved
beyond
the
test
position
without
the
arc
chutes
and
barriers
in
place
.
OPERATING
POSITION
The
breaker
may
be
moved
from
the
test
to
the
operating
position
by
engaging
the
levering
-
in
i
15
Courtesy of NationalSwitchgear.com

Operation
device
and
rotating
the
levering
-
in
crank
clock
-
wise
.
At
the
end
of
the
travel
,
all
the
breaker
contacts
are
energized
.
This
is
the
operating
position
.
breaker
is
in
any
position
between
the
test
and
operate
position
,
the
pin
in
the
levering
-
in
device
is
extended
blocking
the
pin
from
the
mechanism
.
The
breaker
cannot
be
closed
.
See
Fig
.
10
.
INTERLOCK
SECONDARY
CONTACTS
The
interlock
on
the
50
-
DH
-
350
breaker
has
two
functions
to
perform
.
First
,
it
prevents
the
breaker
from
being
moved
from
the
test
to
the
operate
position
or
vice
versa
with
the
contacts
closed
.
Second
,
if
the
breaker
is
in
some
inter
-
mediate
position
between
the
test
and
operate
position
,
it
prevents
the
contacts
from
being
closed
.
This
interlocking
action
is
accomplished
by
having
two
pins
,
one
operated
by
the
breaker
mechanism
,
and
one
by
the
levering
-
in
device
,
operate
at
right
angles
to
each
other
.
When
the
breaker
is
closed
,
the
mechanism
pin
is
extended
over
the
end
of
the
levering
-
in
device
pin
.
This
prevents
the
pin
from
moving
;
and
if
the
pin
does
not
move
,
the
coupling
cannot
be
engaged
in
the
levering
-
in
device
to
move
the
breaker
.
When
the
The
breaker
control
wiring
is
arranged
for
draw
-
out
disconnection
by
means
of
an
18
-
point
connector
block
arranged
to
plug
into
a
mating
block
mounted
on
the
cell
.
The
secondary
connector
block
is
mount
-
ed
on
a
movable
bracket
on
the
lower
left
hand
side
of
the
breaker
frame
.
This
permits
the
18
-
point
connector
block
to
be
extended
to
the
rear
and
make
contact
with
stationary
member
so
that
the
control
circuits
are
made
up
while
the
breaker
is
in
the
test
position
.
To
engage
the
secondary
contacts
while
the
breaker
is
in
the
test
position
,
place
the
breaker
maintenance
closing
handle
in
the
socket
on
the
secondary
contact
slide
at
the
lower
left
hand
side
of
the
breaker
(
Fig
.
13
)
.
Push
forward
slightly
to
16
Courtesy of NationalSwitchgear.com

I
.
B
.
32
-
251
-
4
Operation
,
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
>
SHUTTER
ROLLER
1
i
LEVERING
-
IN
DEVICE
ARM
FIG
.
12
.
Rear
View
of
1200
Amp
.
,
50
-
DH
-
350
Breaker
FIG
.
11
.
Rear
View
of
3000
Amp
.
,
50
-
DH
-
350
Breaker
release
the
latch
and
raise
up
on
a
handle
to
the
end
of
the travel
.
See
Fig
.
14
.
PUFFER
ASSEMBLY
Directly
behind
the
mechanism
is
a
puffer
ar
-
rangement
that
supplies
a
jet
of
air
to
each
of
the
contacts
through
an
insulating
tube
and nozzle
.
Since
the blowout
force
of
small
arcs
is
very
light
,
the
jet
of
air
is
released
at
the
instant
the breaker
is
tripped
.
This facilitates the
movement
of
the
arc
into
the
arc
chute where
it
is
quickly
interrupted
.
The
arrangement
is
shown
in
Fig
.
18
.
The
diaphragm
is
connected
to
the
operating
mechanism
through
the
two
operating
rods
.
As
the
breaker
trips
open
,
the
diaphragm
is
drawn
into
the
cavity
expelling
the
air
which
is
directed
to
the
contacts
by
the
puffer
nozzles
.
The
diaphragm
is
made
of
longlasting
wide
temperature
range
material and should
never
require
replacement
unless
through
accidental
puncturing
.
>
FIG
.
13
.
Front
View
Showing
Socket
for
Operating
Secondary
Contacts
17
Courtesy of NationalSwitchgear.com

Operation
ARC
CHUTE
LIFTER
In
order
to
raise
the
arc
chutes
for
contact
inspection
and
maintenance
,
an
arc
chute
lifter
is
provided
.
It
consists
of
a
piece
of
round
bar
and
two
lengths
of
channel
and
the
necessary
hardware
to
mount
it
to
the
breaker
.
With
the
breaker
out
of
the
cell
and
the
barrier
removed
,
the
following
procedure
may
be
followed
in
raising
the
arc
chutes
.
First
,
remove
the
bolts
which
connects
the
front
arc
horn
in
the
arc
chute
to
the
arc
chute
support
casting
.
Next
,
the
round
bar
is
placed
through
the
U
/
2
"
diameter
holes
in
the
front
of
the
arc
chutes
.
The
two
channel
members
are
then
connected
from
the
round
bar
to
the
rollers
on
the
levering
-
in
device
arms
.
Then
by
operating
the
levering
-
in
device
in
the
same
man
-
‘
ner
as
though
moving
the
breaker
into
the
cell
,
the
arc
chutes
can
be
raised
.
(
See
Fig
.
3
)
.
The
full
travel
of
the
levering
-
in
device
must
be
used
in
raising
the
arc
chute
in
order
to
release
the
interlock
so
that
the
contacts
may
be
closed
to
check
them
for
proper
adjustment
.
FIG
.
15
.
Pole
Unit
Assembly
18
Courtesy of NationalSwitchgear.com

I
.
B
.
32
-
251
-
4
50
-
DH
-
350
AIR
CIRCUIT
BREAKER
PART
FOUR
>
INSTALLATION
With
the
exception
of
the
arcing
chambers
and
barriers
,
the
breakers
are
shipped
completely
as
-
sembled
and
adjusted
.
No
adjustment
should
be
required
and
none
should
be
made
unless
obviously
needed
.
Caution
:
Severe
injury
may
be
sustained
if
any
part
of
the
body
is
struck
by
the
contact
arms
since
they
move
very
rapidly
in
the
opening
stroke
.
Personnel
working
about
the
breaker
should
stay
clear
of
the
space
in
which
the
contact
arms
move
while
the
breaker
is
closed
or
being
closed
.
Never
trip
the
breaker
with
the
hand
-
closing
lever
in
place
.
Place
the
breaker
in
a
convenient
position
adja
-
cent
the
test
cabinet
or
in
front
of
the
metalclad
cell
in
which
it
will
go
.
Then
perform
the
following
sequence
of
operations
to
place
the
breaker
in
service
.
1
.
Remove
tie
on
hand
-
trip
lever
.
Breakers
are
shipped
with
the
contacts
closed
and
a
tie
on
the
hand
-
trip
lever
to
prevent
tripping
.
Take
off
the
tie
on
the
trip
lever
and
trip
the
breaker
.
2
.
Wipe
off
breaker
main
and
arcing
con
-
tacts
.
A
light
film
of
grease
is
applied
to
the
con
-
tacts
before
the
breaker
is
operated
.
This
film
is
normally
removed
before
shipment
.
Be
sure
con
-
tacts
are
free
of
grease
before
placing
in
service
.
3
.
Close
breaker
by
hand
.
Place
the
hand
closing
handle
in
the
closing
socket
on
the
breaker
mechanism
and
push
down
to
close
the
breaker
.
As
the
contacts
close
near
the
end
of
the
stroke
,
the
force
necessary
to
close
the
breaker
increases
rapidly
.
4
.
Check
contact
adjustment
.
The
breaker
contacts
are
properly
adjusted
when
the
difference
between
the
breaker
closed
and
breaker
open
posi
-
tion
as
measured
across
the
outside
of
the
top
pair
of
main
contact
fingers
is
Vs
±
%
4
-
inch
.
(
See
Fig
.
15
)
.
If
adjustment
is
required
,
it
is
made
by
loosening
the
two
lock
nuts
on
the
lower
end
of
the
operating
rods
and
turning
the
adjusting
stud
to
lengthen
or
shorten
the
lift
rods
as
required
.
Be
sure
to
tighten
the
lock
nuts
after
adjusting
the
contacts
.
5
.
Trip
the
breaker
.
The
breaker
is
tripped
both
manually
and
electrically
by
lifting
up
on
the
hand
trip
assembly
on
the
front
of
the
breaker
mechanism
panel
.
6
.
Close
and
trip
the
breaker
.
Close
and
trip
the
breaker
manually
several
times
to
be
certain
that
all
parts
are
functioning
properly
.
7
.
Connect
test
jumper
.
Connect
the
test
jumper
from
the
test
cabinet
to
the
breaker
sec
-
ondary
contact
block
and
operate
the
breaker
electrically
several
times
.
Breaker
operation
should
be
quick
and
positive
in
both
closing
and
tripping
.
8
.
Inspect
arc
chute
.
Before
installing
the
arc
chutes
,
play
a
stream
of
dry
compressed
air
through
them
from
each
end
to
remove
any
dust
or
foreign
matter
.
Then
examine
the
arc
chutes
to
make
certain
the
vents
and
slots
are
open
and
free
from
obstructions
.
9
.
Mount
arc
chutes
.
Mount
the
arc
chutes
one
at
a
time
in
the
following
manner
:
(
a
)
Lift
the
arc
chutes
by
hooking
into
the
arc
chute
lifting
lugs
attached
to
the
blowout
magnets
or
the
%
inch
stud
passing
through
the
center
of
the
arc
chute
near
the
top
.
(
b
)
Remove
the
hinge
pin
from
the
hinge
bracket
on
the
bushing
support
.
(
c
)
Lower
arc
chute
in
place
so
the
back
end
is
between
hinge
bracket
on
bushing
support
bar
.
Use
care
in
aligning
the
arc
chutes
so
that
the
rear
arc
horn
clip
makes
good
contact
with
the
upper
contact
foot
.
The
front
of
the
arc
chute
will
rest
on
the
shunt
casting
which
will
also
serve
as
an
arc
chute
support
.
(
d
)
Insert
hinge
pin
and
put
cotter
pins
in
place
.
(
e
)
Bolt
front
arc
horn
to
shunt
casting
.
(
f
)
Make
final
check
by
operating
breakers
slowly
by
hand
to
see
that
there
is
no
interference
with
movement
of
the
contacts
.
10
.
Mount
the
barrier
.
When
mounting
the
barrier
,
the
lower
rear
comers
of
the
outside
plates
go
to
the
inside
of
the
breaker
frame
.
Two
bolts
in
the
lower
front
comers
hold
the
assembly
in
place
.
11
.
Prepare
levering
4
n
device
to
move
breaker
into
cell
.
Breakers
are
shipped
with
levering
-
in
device
in
the
position
shown
in
Fig
.
12
.
Before
placing
the
breaker
in
the
cell
,
the
levering
-
in
device
roller
arms
must
be
pointed
to
the
rear
of
the
breaker
and
slightly
downward
as
shown
in
Fig
.
11
.
To
put
the
levers
in
the
position
just
de
-
scribed
,
place
the
crank
over
the
shaft
extending
through
the
right
front
comer
of
the
mechanism
t
i
19
Courtesy of NationalSwitchgear.com