Powell PowlVac 01.4IB.50032C User manual

01.4IB.50032C PowlVac® DHP 15kV
Replacement Vacuum Circuit Breaker
Replacement for Westinghouse Type DHP
Air-Magnetic Circuit Breaker
Powered by Safety
®

Powered by Safety®
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
Contact Information
Powell Electrical Systems, Inc.
www.powellind.com
[e-mail]
Service Division
PO Box 12818
Houston, Texas 77217-2818
Tel: [phone]
Fax: [phone]

Powered by Safety®
01.4IB.50032C
Signal Words
As stated in ANSI Z535.4-2007, 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”, “Caution” and “Notice”.
These words are defined as:
DANGER indicates an imminently hazardous
situation which, if not avoided, will result in
death or serious injury.
!
DANGER
!
WARNING
WARNING indicates a potentially hazardous
situation which, if not avoided, could result in
death or serious injury.
!
CAUTION
CAUTION, used with the safety alert symbol,
indicates a hazardous situation which, if not
avoided, could result in minor or moderate
injury.
CAUTION, used without the safety alert
symbol, is used to address practices not
related to personal injury.
CAUTION
NOTICE
NOTICE is used to address practices not related
to personal injury.
Qualified Person
For the purposes of this manual, a qualified
person, as stated in NFPA 70E®, is one who has
skills and knowledge related to the construction
and operation of the electrical equipment and
installations and has received safety training to
recognize and avoid 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.

Powered by Safety®i
01.4IB.50032C
Contents
Ch 1 General Information ................................................................................................1
A. Scope ...............................................................................................................................................................2
B. purpoSe ............................................................................................................................................................2
c. InStructIon BulletInS AvAIlABle electronIcAlly ....................................................................................................2
D. ASSocIAteD InStructIon BulletInS ........................................................................................................................2
Ch 2 Safety .......................................................................................................................3
A. SAfe Work conDItIon .........................................................................................................................................3
B. SAfety GuIDelIneS ...............................................................................................................................................3
c. GenerAl ............................................................................................................................................................4
D. SpecIfIc .............................................................................................................................................................4
e. X-rAyS .............................................................................................................................................................5
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 ............................................................................................................................................................15
c. rAckInG MechAnISM ........................................................................................................................................ 18
1) General Description ..............................................................................................................................................................18
D. Moc (MechAnISM operAteD cell SWItch) ActuAtor .......................................................................................... 21
e. rollout truck ............................................................................................................................................... 21
f. SeconDAry contActS ....................................................................................................................................... 21
G. GrounD contAct ............................................................................................................................................ 22
h. Shutter rollerS ............................................................................................................................................. 22
I. vAcuuM InterrupterS ....................................................................................................................................... 22
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 ...................................................................................................................................................................26
3) Control Voltage Insulation Integrity .................................................................................................................................27
4) Mechanical Operation Check .............................................................................................................................................27
5) Electrical Operation Check ..................................................................................................................................................28
6) Dimensional Check ...............................................................................................................................................................28
e. InSertInG the cIrcuIt BreAker Into the cIrcuIt BreAker coMpArtMent ................................................................... 29
1) Prior to Inserting the Circuit Breaker into the Circuit Breaker Compartment .........................................................29
2) Inserting the Circuit Breaker to the Test/Disconnected Position ................................................................................30
3) Inserting the Circuit Breaker to the Connected Position ..............................................................................................31

Powered by Safety®
ii
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
Contents
f. reMovInG the cIrcuIt BreAker froM the cIrcuIt BreAker coMpArtMent ................................................................. 32
1) Removing the Circuit Breaker from the Connected to the Test/Disconnected Position .......................................32
2) Removing the Circuit Breaker from the Test/Disconnected Position out of the
Circuit Breaker Compartment ............................................................................................................................................32
Ch 5 Maintenance ..........................................................................................................33
A. GenerAl ........................................................................................................................................................... 33
1) Introduction ............................................................................................................................................................................33
2) Inspection and Cleaning ......................................................................................................................................................34
B. MechAnISM AreA ............................................................................................................................................. 34
1) Mechanical Operation .........................................................................................................................................................34
2) Lubrication ..............................................................................................................................................................................35
3) Closing Spring Removal .......................................................................................................................................................39
4) Slow Closing of Mechanism ................................................................................................................................................40
5) Mechanism Adjustments .....................................................................................................................................................40
6) Electrical Operation ..............................................................................................................................................................43
c. vAcuuM Interrupter AnD contAct AreA ............................................................................................................ 43
1) Vacuum Interrupter and Contact Erosion .......................................................................................................................43
2) Sliding Contact Wear ............................................................................................................................................................44
3) Vacuum Integrity ...................................................................................................................................................................44
4) Mechanical Adjustment of Vacuum Interrupters ..........................................................................................................44
D. optIonAl MAIntenAnce proceDureS .................................................................................................................. 44
1) High Potential Tests ..............................................................................................................................................................44
2) Timing ......................................................................................................................................................................................44
3) Primary Resistance Check ...................................................................................................................................................45
Ch 6 Recommended Renewal Parts and Replacement Procedures ..............................46
A. orDerInG InStructIonS ..................................................................................................................................... 46
B. recoMMenDeD reneWAl pArtS .......................................................................................................................... 46
1) Vacuum Interrupter Assembly ............................................................................................................................................46
2) Sliding Contact Finger Assembly .......................................................................................................................................51
3) Closing Coil Assembly ...........................................................................................................................................................51
4) Primary Shunt Trip Coil Assembly ......................................................................................................................................51
5) Secondary Shunt Trip Coil Assembly .................................................................................................................................51
6) Undervoltage Device Assembly (UV) ................................................................................................................................51
7) Charging Motor Assembly ..................................................................................................................................................51
8) Anti-Pump Relay Assembly .................................................................................................................................................51
9) Latch Check Switch ...............................................................................................................................................................51
10) Motor Cutoff Switch Assembly ...........................................................................................................................................52
11) Auxiliary Switch .....................................................................................................................................................................52

Powered by Safety®iii
01.4IB.50032C
Figures
Figure 1 PowlVac®DHP Replacement Circuit Breaker - Front View ............................7
Figure 2 PowlVac®DHP Replacement Circuit Breaker - Front Cover Removed ...........8
Figure 3 PowlVac®DHP Replacement Circuit Breaker Mechanism .............................9
Figure 4 PowlVac®DHP Replacement Circuit Breaker - Rear View ............................10
Figure 5 Cam and Fundamental Linkage Positions ...................................................12
Figure 6 Mechanism and Trip Linkages .....................................................................13
Figure 7 Operation Sequence ....................................................................................16
Figure 8 Typical Control Scemes ................................................................................17
Figure 9 Racking Device and Interlock ......................................................................19
Figure 10 Lubrication ...................................................................................................37
Figure 11 Lubrication (cont) .........................................................................................38
Figure 12 Main Closing Spring Assembly Compressed for Removal ...........................39
Figure 13 Main Closing Spring Assembly Installed .....................................................39
Figure 14 Primary & Secondary Trip Prop Adjustment ...............................................41
Figure 15 Latch Check Switch Adjustment ...................................................................42
Figure 16 Tension Relieved on Opening Springs .........................................................47
Figure 17 Operating Pin Removal ................................................................................47
Figure 18 Lower Contact Block Setting ........................................................................48
Figure 19 Bell Crank Removal ......................................................................................49
Figure 20 Operating Yoke Setting ................................................................................49
Figure 21 Primary Current Path ...................................................................................53
Figure 22 Control Devices ............................................................................................55

Powered by Safety®
iv
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
Tables
Table A Field Dielectric Test Values ..................................................................................25
Table B Lubrication .........................................................................................................36
Table C Timing .................................................................................................................44
Table D Primary Resistance .............................................................................................45
Table E Primary Current Path ..........................................................................................53
Table F Control Devices ...................................................................................................54
Table G Miscellaneous Parts ...........................................................................................56

Powered by Safety®1
General Information
01.4IB.50032C
Ch 1 General Information
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 qualified 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.
!
WARNING
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.
!
WARNING
The information in this instruction bulletin is not intended to explain all details or variations of the
Powell equipment, 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.
NOTICE
Powell reserves the right to discontinue and to change specifications at any time without incurring
any obligation to incorporate new features in products previously sold.
NOTICE

Powered by Safety®
2General Information
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
A. Scope
The information in this instruction bulletin
describes the following PowlVac®DHP
replacement vacuum circuit breakers:
• 15PV25DHP - 500MVA
• 15PV36DHP - 750MVA
• 15PV50DHP - 1000MVA
B. purpoSe
The information in this instruction bulletin is
intended to provide information required to
properly operate and maintain the
PowlVac DHP replacement 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 DHP 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 and photos 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.
!
WARNING
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
Changes to the instruction bulletin may be
implemented at any time and without notice.
Go to www.powellind.com to ensure use of
the current instruction bulletin for the Powell
equipment.
NOTICE
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].
For specific questions or comments pertaining
to this instruction bulletin email
[e-mail] with the IB
number in the subject line.
D. ASSocIAteD InStructIon BulletInS
• 01.4IB.51801 Remote Racking Device for
PowlVac® DHP

Powered by Safety®3
Safety
01.4IB.50032C
Ch 2 Safety
A. SAfe Work conDItIon
The information in Section A is quoted from
NFPA 70E 2012 - 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.
Informational Note: See ANSI/ISA-61010-1
(82.02.01)/UL 61010-1, Safety Requirements
for Electrical Equipment for Measurement,
Control, and Laboratory Use - Part 1: General
Requirements, for rating and design
requirements for voltage measurement
and test instruments intended for use on
electrical systems 1000 V and below.
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 replacement 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 replacement 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® DHP replacement vacuum circuit
breakers.

Powered by Safety®
4Safety
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
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.
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.

Powered by Safety®5
Safety
01.4IB.50032C
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.
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.
NOTICE

Powered by Safety®
6Equipment Description
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
Ch 3 Equipment Description
A. GenerAl
The PowlVac®DHP replacement vacuum
circuit breaker (Figure 1) is a special version
of the PowlVac vacuum circuit breaker. It is
designed to replace a Westinghouse Type DHP
Air-Magnetic circuit breaker. The PowlVac DHP
circuit breaker is mounted on a frame similar
to the frame of the Westinghouse Type DHP
circuit breaker and is equipped with primary
disconnects, a secondary disconnect plug,
interlocks, and wheels. The entire assembly
fits into a metal-clad switchgear compartment
designated for a Westinghouse Type DHP
circuit breaker without modification to that
compartment. All interlocking provided on the
Westinghouse Type DHP circuit breaker is also
provided on the PowlVac DHP replacement
circuit breaker. Primary connections to the
associated metal-clad switchgear are made by
primary disconnecting devices
(Figure 4, f & i). The busbars and vacuum
interrupter assemblies are supported by high
voltage insulators (Figure 4, b) specifically
designed for the application.
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 interrupters
moving contact assemblies through contact
operating pushrods (Figure 1, n). The racking
mechanism, located in the circuit breaker
truck below the circuit breaker mechanism,
controls the movement of the circuit breaker
between the test/disconnected and connected
positions. The racking device provides the
motion to engage or disengage the primary
disconnecting devices and to open or close the
shutters in metal-clad switchgear.
B. the StoreD enerGy MechAnISM
1) Mechanical Description
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 (10) (Figure 1, a). The bolts
may be removed to allow access to the
stored energy mechanism and its interlocks,
auxiliary switches, and other control
devices.
!
CAUTION
Prior to removing the front cover, the user
must make sure the circuit breaker is in the
OPEN position and the main closing spring is
fully discharged. Failure to do so may result
in 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 is located on the mechanism
escutcheon (Figure 1, d).

Powered by Safety®7
Equipment Description
01.4IB.50032C
Figure 1 PowlVac®DHP Replacement Circuit Breaker - Front View
a. Cover Bolt
b. Blank Panel
c. Handle
d. Escutcheon
e. Manual Trip Operator
f. Manual Charging Crank
g. Breaker Open/Closed Indicator
h. Manual Close Operator
i. Operations Counter
j. Spring Charge Indicator
k. Racking Shaft
l. Secondary Disconnect Hand Operating Rod
m. Wheel
n. Turning Dolly Bracket
a
b
c
f
i
l
nm
k
j
h
g
e
d

Powered by Safety®
8Equipment Description
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
Figure 2 PowlVac®DHP Replacement Circuit Breaker - Front Cover Removed
a. Anti-Pump Relay
b. Opening Spring
c. Connecting Rod
d. Main Closing Spring
e. Shock Absorber (Dashpot)
f. Primary Shunt Trip Coil
g. Auxiliary Switch
h. Charging Motor
a
c
e
f
gh
d
b

Powered by Safety®9
Equipment Description
01.4IB.50032C
Figure 3 PowlVac®DHP Replacement Circuit Breaker Mechanism
a. Main Closing Spring
b. Connecting Rod
c. Primary Shunt Trip Coil
d. Secondary Trip Prop
e. Main Cam Roller
f. Reset Spring
g. Camshaft
h. Main Closing Cam
i. Secondary Trip Prop Adjusting
Screw
a
b
d
e
g
i
j
k
m
o
q
s
v
l
n
p
r
t
u
x
z
w
y
f
h
c
j. Latch Check Switch
k. Jackshaft
l. Holding Pawl Support Arm
m. Crank Pin
n. Holding Pawl Adjusting Eccentric
o. Crank Arm
p. Ratchet Wheel
q. Pawl Lift Drive Plate
r. Close Latch Arm
s. Drive Pawl
t. Close Latch Shaft
u. Closing Coil
v. Pawl Support Arm
w. Motor Cutoff Cam
x. Close Bar Adjusting Screw
y. Charging Motor Drive Shaft
z. Motor Cutoff Switch

Powered by Safety®
10 Equipment Description
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
Figure 4 PowlVac®DHP Replacement Circuit Breaker - Rear View
a. Lift Point
b. Main Insulator (Wishbone)
c. Upper Support Plate
d. Upper Primary Riser
e. Vacuum Interrupter
f. Upper Primary Disconnect Device
g. Strut Kit
h. Standoff Insulator
i. Lower Primary Disconnect Device
j. Shutter Roller
k. Secondary Disconnect Plug
l. MOC Actuator
m. Ground Contact
n. Rail Latch
o. Guide Tube
p. Sliding Contact Finger Assembly
q. Horizontal Connector Bar
r. Operating Pin
s. Bell Crank
t. Spring Yoke
u. Contact Loading Spring
v. Operating Pushrod
a
b
e
g
j
l
n
o
m
k
i
h
f
d
c
qp
r
s
t
u
v

Powered by Safety®11
Equipment Description
01.4IB.50032C
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.
The charging motor (Figure 2, h), 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 from the right
to the left 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 3, g). The drive pawl
(Figure 3, s), which is supported by the
arms, engages with 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 adjustable
by the holding pawl adjusting eccentric
(Figure 3, n), located to 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.
The ratchet wheel (Figure 3, p) has
projections from its side faces which
engage the drive plates as it rotates.
These drive plates are attached to the
camshaft, thus causing the camshaft
to rotate. Attached to the ends of the
camshaft are crank arms (Figure 3, o). The
crank pins (Figure 3, m) on the crank arms
point outward. The crank arms engage
the bottom ends of the connecting rods
(Figure 2, c). 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 will 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 drive plate
(Figure 3, q), and the motor cut off switch is
operated. The motor cut off switch
(Figure 3, z), located to the right of the
mechanism, is operated by the spring
charge indicator and motor cutoff cam
(Figure 3, w). The spring charge indicator
(Figure 1, j) displays that the mechanism
is charged. The camshaft would continue
to rotate, except that it is restrained by
the close latch arm (Figure 3, r) engaging
against the close latch shaft (Figure 3, t).
The main closing cam, located between the
mechanism side sheets, is now in a position
where the fundamental linkage can move
to the reset position.

Powered by Safety®
12 Equipment Description
PowlVac® DHP 15kV Replacement Circuit Breaker 01.4IB.50032C
Figure 5 Cam and Fundamental Linkage Positions
d) Breaker Closed - Spring Charged
b) Breaker Closed - Spring Discharged
a) Breaker Open - Spring Charged - Links Reset
c) Breaker Open - Spring Discharged

Powered by Safety®13
Equipment Description
01.4IB.50032C
Figure 6 Mechanism and Trip Linkages
l
c
b
d
e
f
g
h
i
j
k
a
m
a. Secondary Trip Prop Adjusting Screw
b. Secondary Trip Prop Shaft
c. Secondary Trip Prop
d. Secondary Linkage Roller
e. Main Cam Roller
f. Reset Spring
g. Camshaft
h. Main Closing Cam
i. Center Phase Operating Lever
j. Jackshaft
k. Primary Trip Prop Roller
l. Primary Trip Prop Adjusting Screw
m. Primary Trip Prop