Powell PowlVac ASD User manual

IB-65100 PowlVac® ASD
27kV & 38kV Vacuum Circuit Breaker
27kV & 38kV Circuit Breaker with
Automatic Secondary Disconnect
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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
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IB-65100
Contact Information
Powell Electrical Systems, Inc.
www.powellind.com
[e-mail]
Service Division
PO Box 12818
Houston, Texas 77217-2818
Tel: [phone]
Fax: [phone]

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Signal Words
As stated in ANSI Z535.4-2002, § 4.13-4.13.3 the
signal word is a word that calls attention to the
safety sign and designates a degree or level of
hazard seriousness. The signal words for product
safety signs are “Danger”, “Warning”, and
“Caution”. These words are defined as:
DANGER indicates an imminently hazardous
situation which, if not avoided, will result in
death or serious injury.
DANGERDANGER
!
WARNING indicates a potentially hazardous
situation which, if not avoided, could result in
death or serious injury.
WARNINGWARNING
!
CAUTIONCAUTION
!
CAUTION indicates a potentially hazardous
situation which, if not avoided, may result in
minor or moderate injury.
Not stated in ANSI Z535.4-2002, § 4.13-4.13.3
as a signal word but used in this manual is
“IMPORTANT”. This is defined as:
IMPORTANT indicates a section of the manual
covering a non hazardous situation, but
one where Powell feels proper attention is
warranted.
IMPORTANTIMPORTANT
!
Qualified Person
For the purposes of this manual, a qualified person,
as stated in NFPA 70®, is one familiar with the
construction and operation of the equipment and
the hazards involved.
In addition to the above qualifications, one must
also be:
1) trained and authorized to energize,
deenergize, clear, ground, and tag circuits
and equipment in accordance with
established safety practices.
2) trained in the proper care and use of
personal protective equipment (PPE)
such as rubber gloves, hard hat, safety
glasses or face shields, flash clothing, etc.,
in accordance with established safety
practices.
3) trained in rendering first aid if necessary.

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IB-65100
Contents
Ch 1 General Information.................................................................................................1
A. SCOPE ................................................................................................................................................................2
B. PURPOSE.............................................................................................................................................................2
C. INSTRUCTION BULLETINS AVAILABLE ELECTRONICALLY.....................................................................................................2
Ch 2 Safety ........................................................................................................................3
A. SAFE WORK CONDITION .........................................................................................................................................3
B. SAFETY GUIDELINES ...............................................................................................................................................3
C. GENERAL.............................................................................................................................................................3
D. SPECIFIC ..............................................................................................................................................................4
E. X-RAYS ..............................................................................................................................................................4
F. SAFETY LABELS .....................................................................................................................................................5
Ch 3 Equipment Description.............................................................................................6
A. GENERAL.............................................................................................................................................................6
B. THE STORED ENERGY MECHANISM ............................................................................................................................6
1) Mechanical Description.......................................................................................................................................................... 6
2) Electrical Description.............................................................................................................................................................17
C. RACKING MECHANISM ......................................................................................................................................... 19
1) General Description...............................................................................................................................................................19
2) Circuit Breaker Racking Mechanism..................................................................................................................................20
D. CIRCUIT BREAKER COMPARTMENT INTERFACES ........................................................................................................... 20
1) Primary Disconnecting Contacts........................................................................................................................................20
2) Secondary Disconnecting Contacts ..................................................................................................................................21
3) Mechanism Operated Cell (MOC) Switch .........................................................................................................................21
4) Ground Connection ...............................................................................................................................................................21
E. VACUUM INTERRUPTER CONNECTIONS ..................................................................................................................... 21
F. OPERATING SOLENOIDS ....................................................................................................................................... 22
G. ANTI-PUMP RELAY ............................................................................................................................................. 22
H. MOTOR CUTOFF SWITCH...................................................................................................................................... 22
I. VACUUM INTERRUPTERS ....................................................................................................................................... 22
J. SHUTTER OPERATOR ........................................................................................................................................... 22
K. TEST POSITION INTERLOCK .................................................................................................................................... 22

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Contents
Ch 4 Installation..............................................................................................................23
A. RECEIVING ........................................................................................................................................................ 23
B. HANDLING........................................................................................................................................................ 23
C. STORAGE.......................................................................................................................................................... 23
D. PLACING THE CIRCUIT BREAKER INTO SERVICE............................................................................................................ 24
1) High-Voltage Insulation Integrity.......................................................................................................................................24
2) Vacuum Integrity....................................................................................................................................................................25
3) Control Voltage Insulation Integrity ..................................................................................................................................26
4) Mechanical Operation Check..............................................................................................................................................26
5) Electrical Operation Check...................................................................................................................................................27
E. INSERTING THE CIRCUIT BREAKER INTO THE SWITCHGEAR EQUIPMENT .............................................................................. 27
1) Inserting the Circuit Breaker to the Connected Position...............................................................................................27
2) Inserting the Circuit Breaker to the Test/Disconnect Position .....................................................................................29
F. REMOVING THE CIRCUIT BREAKER FROM THE SWITCHGEAR EQUIPMENT ............................................................................ 29
1) Removing the Circuit Breaker from the Connected to the Test/Disconnected Position........................................29
2) Removing the Circuit Breaker from the Test/Disconnect Position out of the Circuit Breaker Compartment...30
3) Removing the Circuit Breaker with Test Plug Interlock Engaged................................................................................30
Ch 5 Maintenance...........................................................................................................31
A. GENERAL DESCRIPTION ........................................................................................................................................ 31
1) Introduction.............................................................................................................................................................................31
2) Inspection and Cleaning ......................................................................................................................................................32
B. MECHANISM AREA ............................................................................................................................................. 33
1) Mechanical Operation ..........................................................................................................................................................33
2) Lubrication...............................................................................................................................................................................33
3) Closing Spring Removal........................................................................................................................................................37
4) Slow Closing of Mechanism.................................................................................................................................................38
5) Mechanism Adjustments......................................................................................................................................................38
6) Electrical Operation...............................................................................................................................................................44
C. VACUUM INTERRUPTER AND CONTACT AREA ............................................................................................................. 44
1) Vacuum Interrupter and Contact Erosion ........................................................................................................................44
2) Vacuum Integrity....................................................................................................................................................................45
3) Mechanical Adjustment of Vacuum Interrupters .................................................................................................................45
D. OPTIONAL MAINTENANCE PROCEDURES ................................................................................................................... 45
1) High Potential Tests ...............................................................................................................................................................45
2) Timing ......................................................................................................................................................................................46
3) Primary Resistance Check ....................................................................................................................................................46

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IB-65100
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Contents
Ch 6 Recommended Renewal Parts and Replacement Procedures ...............................47
A. ORDERING INSTRUCTIONS ..................................................................................................................................... 47
B. RECOMMENDED RENEWAL PARTS ........................................................................................................................... 47
C. REPLACEMENT PROCEDURES.................................................................................................................................. 47
1) Vacuum Interrupter Assembly.............................................................................................................................................48
2) Closing Coil Assembly ...........................................................................................................................................................56
3) Primary Shunt Trip Coil Assembly ......................................................................................................................................56
4) Secondary Shunt Trip Coil Assembly .................................................................................................................................57
5) Undervoltage Device Assembly (UV).................................................................................................................................57
6) Charging Motor Assembly ...................................................................................................................................................58
7) Anti-Pump Relay Assembly..................................................................................................................................................59
8) Latch Check Switch................................................................................................................................................................60
9) Motor Cutoff Switch Assembly............................................................................................................................................60
10) Auxiliary Switch ......................................................................................................................................................................61

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Figures
Tables
Table A Field Dielectric Test Values..........................................................................................................25
Table B Lubrication ..................................................................................................................................36
Table C Timing..........................................................................................................................................46
Table D Primary Resistance .....................................................................................................................46
Table E Primary Current Path ..................................................................................................................51
Table F Control Devices............................................................................................................................52
Table G Miscellaneous Parts....................................................................................................................54
Figure 1 Front View of PowlVac® ASD Circuit Breaker with Cover....................................................7
Figure 2 Rear View of PowlVac® ASD Circuit Breaker........................................................................8
Figure 3 PowlVac® ASD Circuit Breaker Compartment.....................................................................9
Figure 4 Operating Pushrod Assembly of PowlVac® 38kV ASD Circuit Breaker.............................10
Figure 5 Ground Connection of PowlVac® ASD 38kV Circuit Breaker ............................................10
Figure 6 Front View of PowlVac® ASD Circuit Breaker without Cover ............................................12
Figure 7 Close-Up Front View of PowlVac® ASD Circuit Breaker Mechanism.................................13
Figure 8 Cam and Fundamental Linkage Positions........................................................................14
Figure 9 Mechanical and Trip Linkages...........................................................................................15
Figure 10 Typical Control Scheme.....................................................................................................18
Figure 11 Test Plug Jumper Interlock ................................................................................................20
Figure 12 Secondary Disconnect Receptacle and Secondary Disconnect Device Completed.........20
Figure 13 Lifting the Circuit Breaker by Crane..................................................................................23
Figure 14 Push to Trip Knob & Racking Access Door.........................................................................28
Figure 15 Racking Indicator Flags & Racking Handle.......................................................................28
Figure 16 Lubrication ........................................................................................................................34
Figure 17 Lubrication (cont) ..............................................................................................................35
Figure 18 Main Closing Spring AssemblyCompressed for Removal.................................................37
Figure 19 Main Closing Spring AssemblyInstalled ...........................................................................37
Figure 20 Primary & Secondary Trip Prop Adjustment.....................................................................39
Figure 21 Feeler Gauge......................................................................................................................40
Figure 22 Trip Armature Assembly Left View....................................................................................41
Figure 23 Trip Armature Assembly Right View .................................................................................42
Figure 24 Circuit Breaker Trip Roller .................................................................................................42
Figure 25 Latch Check Switch Adjustment........................................................................................43
Figure 26 Vacuum Interrupter Assembly Drawing (38kV, 1200A)....................................................50
Figure 27 Primary Current Path ........................................................................................................51
Figure 28 Control Devices..................................................................................................................53

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IB-65100
General Information
WARNINGWARNING
!
The equipment described in this document may contain high voltages and currents which can
cause serious injury or death.
The equipment is designed for use, installation, and maintenance by knowledgeable users of such
equipment having experience and training in the field of high voltage electricity. This document
and all other documentation shall be fully read, understood, and all warnings and cautions
shall be abided by. If there are any discrepancies or questions, the user shall contact Powell
immediately at 1.800.480.7273.
WARNINGWARNING
!
Before any adjustment, servicing, part replacement, or any other act is performed requiring
physical contact with the electrical working components or wiring of this equipment, the power
supply must be disconnected. Failure to follow this warning may result in injury or death.
IMPORTANTIMPORTANT
!
The information in this instruction bulletin is not intended to explain all details or variations of
the PowlVac® ASD 27kV & 38kV circuit breakers, nor to provide for every possible contingency
or hazard to be met in connection with installation, testing, operation, and maintenance of the
equipment. For additional information and instructions for particular problems, which are not
presented sufficiently for the user’s purposes, contact Powell at 1.800.480.7273.
Ch 1 General Information

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
General Information
A. SCOPE
The information in this instruction bulletin
describes the following PowlVac ASD 38kV
vacuum circuit breakers:
• 38PV40ASD - 1200A & 2000A
• 27PV25ASD - 1200A & 2000A
B. PURPOSE
The information in this instruction bulletin is
intended to provide information required to
properly operate and maintain the
PowlVac ASD 38kV vacuum circuit breakers
described in Ch 1 General Information,
A. SCOPE.
This instruction bulletin provides:
1) Safety guidelines
2) General descriptions of the operation and
maintenance of the PowlVac ASD 38kV
vacuum circuit breaker
3) Instructions for installation and placing the
circuit breaker into service
4) Instructions for part replacement
5) Information for ordering renewal parts
6) Procedure for critical adjustments
7) Illustrations, photographs, and description
of the circuit breaker
The illustrations contained in this document
may not represent the exact construction
details of each particular type of replacement
circuit breaker. The illustrations in this
document are provided as general information
to aid in showing component locations only.
All illustrations are shown using deenergized
equipment.
Be sure to follow the appropriate safety
precaution while handling any of the
equipment. Failure to do so may result in
serious injury or death.
WARNINGWARNING
!
To the extent required, the products described
herein meet the applicable ANSI, IEEE, and
NEMA Standards; however, no such assurance
is given with respect to local codes and
ordinances which may vary greatly.
C. INSTRUCTION BULLETINS AVAILABLE ELECTRONICALLY
For more information visit
www.powellind.com. To contact the Powell
Service Division call 1.800.480.7273 or
713.944.6900, or email
[e-mail].

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IB-65100
Safety
Ch 2 Safety
A. SAFE WORK CONDITION
The information in Section A is quoted from
NFPA 70E 2004 - Article 120, 120.1 Establishing an
Electrically Safe Work Condition.
120.1 Process of Achieving an Electrically Safe
Work Condition
1) Determine all possible sources of electrical
supply to the specific equipment. Check
applicable up-to-date drawings, diagrams,
and identification tags.
2) After properly interrupting the load current,
OPEN the disconnecting device(s) for each
source.
3) Wherever possible, visually verify that all
blades of the disconnecting devices are
fully OPEN or that drawout type circuit
breakers are withdrawn to the fully
disconnected position.
4) Apply lockout/tagout devices in accordance
with a documented and established policy.
5) Use an adequately rated voltage detector
to test each phase conductor or circuit part
to verify they are deenergized. Test each
phase conductor or circuit part both
phase-to-phase, and phase-to-ground.
Before and after each test, determine
that the voltage detector is operating
satisfactorily.
6) Where the possibility of induced voltages
or stored electrical energy exists, ground
the phase conductors or circuit parts
before touching them. Where it could be
reasonably anticipated that the conductors
or circuit parts being deenergized
could contact other exposed energized
conductors or circuit parts, apply ground
connecting devices rated for the available
fault duty.
B. SAFETY GUIDELINES
Study this instruction bulletin and all other
associated documentation before uncrating
the circuit breakers.
Each user has the responsibility to instruct
and supervise all personnel associated with
usage, installation, operation, and maintenance
of this equipment on all safety procedures.
Furthermore, each user has the responsibility of
establishing a safety program for each type of
equipment encountered.
The circuit breakers described in this
instruction bulletin are operated by a
high-energy, high-speed mechanism that
is interlocked to provide specific operating
sequences. It is mandatory that the following
rules be observed to ensure the safety of
personnel associated with usage, installation,
operation, and maintenance of these circuit
breakers.
The safety rules in this instruction bulletin are
not intended to be a complete safety program.
The rules are intended to cover only some of the
important aspects of personnel safety related to
PowlVac® ASD 38kV vacuum circuit breakers.
C. GENERAL
1) Only supervised and qualified personnel
trained in the usage, installation, operation,
and maintenance of the circuit breaker shall
be allowed to work on this equipment. It
is mandatory that this instruction bulletin,
any supplements, and service advisories be
studied, understood, and followed.
2) Maintenance programs must be consistent
with both customer experience and
manufacturer’s recommendations,
including service advisories and instruction
bulletin(s). A well planned and executed
routine maintenance program is essential
for circuit breaker’s reliability and safety.

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Safety
3) Service conditions and circuit breaker
applications shall also be considered in the
development of safety programs. Variables
include ambient temperature; humidity;
actual continuous current; thermal cycling;
number of operations; interrupting duty;
and any adverse local conditions including
excessive dust, ash, corrosive atmosphere,
vermin and insect infestations.
D. SPECIFIC
1) DO NOT WORK ON AN ENERGIZED
CIRCUIT BREAKER. If work must be
performed on a circuit breaker, remove it
from service and remove it from the
metal-clad switchgear.
2) DO NOT WORK ON A CIRCUIT BREAKER
WITH THE CONTROL CIRCUIT ENERGIZED.
3) EXTREME CARE MUST BE EXERCISED
TO KEEP ALL PERSONNEL, TOOLS, AND
OTHER OBJECTS CLEAR OF MECHANISMS
WHICH ARE TO BE OPERATED,
DISCHARGED, OR RELEASED. These
circuit breakers utilize stored energy
mechanisms. These mechanisms must be
serviced only by skilled and knowledgeable
personnel capable of releasing each spring
load in a controlled manner. Detailed
information regarding these mechanisms is
found in this instruction bulletin.
4. DO NOT ATTEMPT TO CLOSE THE CIRCUIT
BREAKER MANUALLY ON AN ENERGIZED
CIRCUIT.
5. DO NOT USE AN OPEN CIRCUIT BREAKER
AS THE SOLE MEANS OF ISOLATING A
HIGH VOLTAGE CIRCUIT. For complete
isolation, the circuit breaker shall be in
the disconnected position or shall be
withdrawn completely.
6. ALL COMPONENTS SHALL BE
DISCONNECTED BY MEANS OF A VISIBLE
BREAK AND SECURELY GROUNDED FOR
SAFETY OF PERSONNEL PERFORMING
MAINTENANCE OPERATIONS ON THE
CIRCUIT BREAKERS.
7. Interlocks are provided to ensure the
proper operating sequences of the circuit
breakers and for the safety of the user. If for
any reason an interlock does not function
as described, do not make any adjustments,
modification, or deform the parts. DO
NOT FORCE THE PARTS INTO POSITION.
CONTACT POWELL FOR INSTRUCTIONS.
E. X-RAYS
When high voltage is applied across the
contacts of a vacuum interrupter, there is the
possibility of generation of X-rays. The intensity
of the X-radiation is dependent on the peak
voltage and the contact gap. At the normal
operating voltage for this type of equipment,
the radiation levels are negligible. At the
voltages specified for testing, test personnel
shall be in front of the circuit breaker such that
the two layers of steel used in the frame and
front cover construction are between the test
personnel and the vacuum interrupters, and
that the test personnel be no closer than one
meter (3’) from the front of the circuit breaker.
THE CIRCUIT BREAKER SHALL BE EITHER
FULLY OPEN, OR FULLY CLOSED WHEN
MAKING HIGH POTENTIAL TESTS. DO NOT
TEST WITH CONTACTS PARTIALLY OPEN.

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IB-65100
Safety
F. SAFETY LABELS
The equipment described in this document
has DANGER, WARNING, CAUTION, and
instruction labels attached to various locations.
All equipment DANGER, WARNING, CAUTION,
and instruction labels shall be observed when
the circuit breaker is handled, operated, or
maintained.
Warning and Caution labels are located in
various places in and on the switchgear and
on the circuit breaker removable element.
Always observe these warnings and caution
labels. Do NOT remove or deface any of these
warning/caution labels.
IMPORTANTIMPORTANT
!

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Equipment Description
Ch 3 Equipment Description
A. GENERAL
The PowlVac ASD 38kV vacuum circuit breaker
(Figure 1) is a version of the PowlVac 38kV
CDR (IB-65020) vacuum circuit breaker. It
eliminates the need for an umbilical cord in
the fully connected position. This is done by
incorporating a secondary disconnect plug
on the rear of the circuit breaker (Figure 2, g)
and its corresponding secondary disconnect
receptacle on the circuit breaker base pan
(Figure 3, g).
This PowlVac ASD circuit breaker uses sealed
vacuum interrupters (Figure 2, b) to control the
primary circuit. Primary connections to the
associated metal-clad switchgear are made
by tubular busbars terminating in the finger
clusters of the primary disconnects (Figure 2, a).
The primary current path side of the circuit
breaker is considered the rear of the circuit
breaker. The side with the cover containing
the various indicators and manual operators is
considered the front of the circuit breaker. The
operating mechanisms of the circuit breaker
are exposed by removing the front cover. The
stored energy mechanism assembly provides
motion to each of the vacuum interrupter
moving contact assemblies through contact
operating pushrods. In the same metal
enclosed compartment as the stored energy
mechanism are interlocks which control the
movement of the circuit breaker between the
test/disconnected and connected positions.
B. THE STORED ENERGY MECHANISM
1) Mechanical Description
a) General
The stored energy mechanism is located
in the front of the circuit breaker behind
the front cover. The front cover is held
in place with cover bolts (12) (Figure 1,
g). The bolts may be removed to allow
access to the stored energy mechanism
and its interlocks, auxiliary switches,
and other control devices. It is very
important to ensure that the circuit
breaker is in the“OPEN”position and
the main closing spring (Figure 6, d) is
fully discharged before removing the
front cover. FAILURE TO DO THIS MAY
RESULT IN PERSONAL INJURY.
On the escutcheon of the stored energy
mechanism, there are two (2) indicators
that show the various states of
operation of the mechanism and two (2)
manual operators that will open or close
the stored energy mechanism. The
circuit breaker nameplate (Figure 1, h) is
located on the mechanism escutcheon.
The mechanism employed in the circuit
breaker is a stored energy system which
uses a charging motor to compress the
main closing spring. The energy stored
in the main closing spring is released
during the closing operation. The
released energy allows the mechanism
to close the vacuum interrupter
contacts, compress the contact loading
springs, charge the opening springs,
and overcome frictional forces. When
the circuit breaker is opened, the
energy stored in the opening and
contact loading springs is released, and
the vacuum interrupter contacts are
opened.

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IB-65100
Equipment Description
Figure 1 Front View of PowlVac® ASD
Circuit Breaker with Cover
a. Push to Trip Roller
b. Handle
c. Test Plug Interlocking Device
d. Test Receptacle Guide
e. Test Plug Receptacle with Boot
f. Test Plug Disconnect Latch
g. Front Cover Bolts (12)
h. Nameplate
i. Mechanism Operated Cell Switch (MOC)
Actuator
j. Manual Charging Crank
k. Manual Trip Paddle
l. Breaker Open/Closed Indicator
m. Manual Close Paddle
n. Operations Counter
o. Spring Charge Indicator
p. Test Position Interlock
a
h
g
f
e
d
c
b
i
j
k
l
i
k
i
m
n
o
p

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Equipment Description
Figure 2 Rear View of PowlVac® ASD
Circuit Breaker
a. Primary Disconnect
b. Vacuum Interrupter
c. Lifting Point
d. High Voltage Pushrod
e. Shutter Operator
f. Interference Plate
g. Secondary Disconnect Plug
h. Wheel
a
bc
d
e
fg
h
f
g
c
e
g
f
h

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IB-65100
Equipment Description
Figure 3 PowlVac® ASD Circuit Breaker
Compartment
a. Push to Trip Knob
b. Racking Access Door
c. Primary Disconnect Bushing
d. Shutter
e. Shutter Lift Arm
f. Ground Bus
g. Secondary Disconnect Receptacle
h. Center Alignment Block
i. Compartment Interference Plate
j. Circuit Breaker Base Pan
k. Compartment Interlock Weldment
l. Compartment Mounted Test Umbilical
Receptacle
k
l
a b
c
d
ef
g
h
i
i
j

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Equipment Description
Figure 4 Operating Pushrod Assembly of
PowlVac® 38kV ASD Circuit Breaker
Figure 5 Ground Connection of
PowlVac® ASD 38kV Circuit Breaker

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IB-65100
Equipment Description
b) Main Spring Charging System
The charging motor (Figure 6, i), located
on the bottom right of the base pan, is
assembled to the circuit breaker by a
bracket that is bolted to the base pan.
The charging motor drive shaft inserts
into the eccentric drive shaft. The
eccentric drive shaft is supported by
needle roller bearings in the mechanism
frame side sheets and transmits the
motor torque to the right side of the
mechanism.
When the charging motor is energized,
the eccentric drive shaft rotates and
causes the pawl support arms to pivot
about the camshaft (Figure 7, p). The
drive pawl (Figure 7, m), which is
supported by the arms, engages with
the ratchet wheel and drives the ratchet
wheel one tooth at a time. To prevent
backwards motion of the ratchet wheel,
a spring-loaded holding pawl is used
to latch the ratchet wheel after each
advance from the drive pawl.
To ensure correct synchronization of
the drive and holding pawl, the position
of the holding pawl support arms are
adjusted by the holding pawl adjusting
eccentric (Figure 7, f), located at the
left front of the mechanism. When the
mechanism is operated manually, the
top pawl becomes the drive pawl and
the bottom pawl becomes the holding
pawl.
As the ratchet wheel (Figure 7, i) rotates,
projections from its side faces engage
the drive plates. The drive plates are
attached to the camshaft, and cause
the camshaft to rotate. Crank arms
(Figure 7, h) are attached to the ends of
the camshaft. Crank pins (Figure 7, g)
are assembled to the crank arms, which
point outward. The crank arms engage
the bottom ends of the connecting
rods (Figure 6, e). The pins that project
from the spring yoke, which straddles
the main closing spring, engage the
top ends of the connecting rods. As
the camshaft rotates the connecting
rods pull the spring yoke downward,
compressing the main closing spring.
The ratchet wheel drives the camshaft
so that the connecting rods go down
to their lowest position, and then start
to move upward. At a certain point,
the spring force overcomes friction
and resistance and start to rotate the
camshaft. At the same time, the pawls
are uncoupled from the ratchet wheel
by the pawl lift plate (Figure 7, j), and
the motor cut-off switch is operated.
The motor cut-off switch (Figure 7, t),
located to the right of the mechanism, is
operated by the spring charge indicator
and motor cutoff cam (Figure 7, q). The
spring charge indicator (Figure 1, o)
displays that the mechanism is charged.
The camshaft (Figure 7, p) is restrained
by the close latch arm engaging against
the close latch shaft. The main closing
cam, located between the mechanism
side sheets, is in a position where the
fundamental linkage can move to the
reset position.

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PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Equipment Description
Figure 6 Front View of PowlVac® ASD
Circuit Breaker without Cover
a. Opening Spring
b. Anti-Pump Relay
c. Trip Tube
d. Main Closing Spring
e. Connecting Rod
f. Opening Anti-Below Spring
g. Shock Absorber
h. Auxiliary Switch
i. Charging Motor
a
b
c
i
f
d
h
g
e