Safety POWELL PowlVac-ND User manual
01.4IB.77000B
PowlVac-ND®Vacuum Circuit Breaker
5kV / 1200A & 2000A / 36kA & 50kA
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01.4IB.77000B
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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”, and “Caution”. 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.
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PowlVac-ND® Vacuum Circuit Breaker
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01.4IB.77000B
Contents
Ch 1 General Information ................................................................................................1
A. Scope ...............................................................................................................................................................2
B. purpoSe ............................................................................................................................................................2
c. InStructIon BulletInS AvAIlABle electronIcAlly ....................................................................................................2
D. ASSocIAteD 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 DeScrIptIon ..........................................................................................................................................6
B. the StoreD enerGy MechAnISM ............................................................................................................................6
1) Mechanical Description ......................................................................................................................................................... 6
2) Electrical Description ............................................................................................................................................................15
c. rAckInG MechAnISM ........................................................................................................................................ 16
1) General Description ..............................................................................................................................................................16
2) Closed Door Racking Mechanism .....................................................................................................................................18
D. cIrcuIt BreAker coMpArtMent InterfAceS .......................................................................................................... 18
1) Primary Disconnecting Devices .........................................................................................................................................18
2) Secondary Disconnecting Devices ....................................................................................................................................19
3) MOC (Mechanism Operated Cell Switch) Actuator .......................................................................................................19
4) TOC (Truck Operated Cell Switch) Actuator ....................................................................................................................19
5) Ground Connection ..............................................................................................................................................................19
6) Shutter Rollers ........................................................................................................................................................................19
7) Anti-Rollout Latch .................................................................................................................................................................19
e. vAcuuM InterrupterS ....................................................................................................................................... 20
f. vAcuuM Interrupter connectIonS ..................................................................................................................... 20
Ch 4 Installation .............................................................................................................21
A. receIvInG ........................................................................................................................................................ 21
B. hAnDlInG ....................................................................................................................................................... 21
c. StorAGe ......................................................................................................................................................... 22
D. plAcInG the cIrcuIt BreAker Into ServIce ........................................................................................................... 23
1) High Voltage Insulation Integrity ......................................................................................................................................23
2) Vacuum Integrity ...................................................................................................................................................................24
3) Control Voltage Insulation Integrity .................................................................................................................................25
4) Mechanical Operation Check .............................................................................................................................................26
5) Electrical Operation Check ..................................................................................................................................................27
6) Racking Mechanism Check .................................................................................................................................................28
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01.4IB.77000B
PowlVac-ND® Vacuum Circuit Breaker
Contents
e. InSertInG the cIrcuIt BreAker Into the cIrcuIt BreAker coMpArtMent ................................................................... 28
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
f. reMovInG the cIrcuIt BreAker froM the cIrcuIt BreAker coMpArtMent ................................................................ 32
1) Removing the Circuit Breaker from the Connected to the Test/Disconnected Position .......................................33
2) Removing the Circuit Breaker from the Test/Disconnected Position out of the
Circuit Breaker Compartment ............................................................................................................................................33
3) Remote Racking ....................................................................................................................................................................33
Ch 5 Maintenance ..........................................................................................................34
A. GenerAl DeScrIptIon ....................................................................................................................................... 34
1) Introduction ............................................................................................................................................................................34
2) Inspection and Cleaning ......................................................................................................................................................35
B. MechAnISM AreA ............................................................................................................................................. 36
1) Mechanical Operation .........................................................................................................................................................36
2) Lubrication ..............................................................................................................................................................................36
3) Closing Spring Removal .......................................................................................................................................................40
4) Slow Closing of Mechanism ................................................................................................................................................41
5) Mechanism Adjustments .....................................................................................................................................................41
6) Electrical Operation ..............................................................................................................................................................46
c. vAcuuM Interrupter AnD contAct AreA ............................................................................................................ 46
1) Vacuum Interrupter and Contact Erosion .......................................................................................................................46
2) Sliding Contact Finger Wear ...............................................................................................................................................47
3) Vacuum Integrity ...................................................................................................................................................................47
4) Mechanical Adjustment of Vacuum Interrupters ................................................................................................................47
D. optIonAl MAIntenAnce proceDureS .................................................................................................................. 47
1) High Potential Tests ..............................................................................................................................................................47
2) Timing .....................................................................................................................................................................................48
3) Primary Resistance Check ...................................................................................................................................................48
Ch 6 Recommended Renewal Parts and Replacement Procedures ..............................49
A. orDerInG InStructIonS ..................................................................................................................................... 49
B. recoMMenDeD reneWAl pArtS .......................................................................................................................... 49
c. replAceMent proceDureS ................................................................................................................................. 50
1) Vacuum Interrupter Assembly ............................................................................................................................................50
2) Closing Coil Assembly ...........................................................................................................................................................50
3) Primary Shunt Trip Coil Assembly ......................................................................................................................................50
4) Secondary Shunt Trip Coil Assembly .................................................................................................................................50
5) Undervoltage Device Assembly .........................................................................................................................................50
6) Charging Motor Assembly ..................................................................................................................................................50
7) Anti-Pump Relay Assembly .................................................................................................................................................50
8) Latch Check Switch ...............................................................................................................................................................50
9) Motor Cutoff Switch Assembly ...........................................................................................................................................50
10) Auxiliary Switch .....................................................................................................................................................................50
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01.4IB.77000B
Figures
Figure 1 PowlVac-ND Circuit Breaker - Exterior View ..................................................8
Figure 2 PowlVac-ND® Circuit Breaker - Interior View .................................................9
Figure 3 Cam and Fundamental Linkage Positions ...................................................10
Figure 4 Mechanism and Trip Linkages .....................................................................11
Figure 5 Operation Sequence ....................................................................................13
Figure 6 Typical AC/DC Control Scheme ....................................................................14
Figure 7 Closed Door Racking Mechanism & Interlock .............................................18
Figure 8 Circuit Breaker in Shipping Carton ..............................................................21
Figure 9 Circuit Breaker on Crane ..............................................................................22
Figure 10 Racking of the Circuit Breaker .....................................................................30
Figure 11 Secondary Disconnecting Device ................................................................32
Figure 12 PowlVac-ND®Circuit Breaker Test Position .................................................32
Figure 13 Racking Handle Insertion ............................................................................32
Figure 14 Circuit Breaker Removal Applying the Anti-Rollout Latch ..........................33
Figure 15 Lubrication ...................................................................................................38
Figure 16 Lubrication (cont) .........................................................................................39
Figure 17 Main Closing Spring Assembly Compressed for Removal ...........................40
Figure 18 Main Closing Spring Assembly Installed .....................................................40
Figure 19 Primary & Secondary Trip Prop Adjustment ...............................................42
Figure 20 Feeler Gauge ................................................................................................43
Figure 21 Latch Check Switch Adjustment ...................................................................44
Figure 22 Measurement of Open Position ...................................................................46
Figure 23 Measurement of Closed Position .................................................................46
Figure 24 Primary Current Path ...................................................................................51
Figure 25 Control Devices ............................................................................................53
Tables
Table A Field Dielectric Test Values .................................................................................23
Table B Lubrication .........................................................................................................37
Table C Timing .................................................................................................................48
Table D Primary Resistance .............................................................................................48
Table E Primary Current Path ..........................................................................................51
Table F Control Devices ...................................................................................................52
Table G Miscellaneous Parts ...........................................................................................54
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01.4IB.77000B
General Information
Ch 1 General Information
!
WARNING
The equipment described in this document may contain high voltages and currents which can
cause death or serious injury.
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.
!
WARNING
Prior to adjustments, servicing, maintenance, or any act requiring the operator to make physical
contact with the equipment, the power source must be disconnected and the equipment grounded.
Failure to do so may result in death or serious injury.
NOTICE
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.
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
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01.4IB.77000B
General Information
PowlVac-ND® Vacuum Circuit Breaker
A. Scope
This instruction bulletin is intended to assist
users in the design and safe operation of these
PowlVac-ND® circuit breakers:
• 05PV36SNDX, 1200 & 2000A
• 05PV50SNDX, 1200 & 2000A
B. purpoSe
This instruction bulletin is intended to provide
the information required to properly operate
and maintain the circuit breakers described in
Ch 1 General Information, A. Scope.
This instruction bulletin provides:
1. Guidelines for safety.
2. General descriptions of the operation and
maintenance of the circuit breakers.
3. Instructions for installation and placing the
circuit breakers into service.
4. Instructions for part replacement.
5. Renewal parts lists.
The illustrations contained in this document
may not represent the exact construction
details of each particular type of circuit breaker.
The illustrations in this document are provided
as general information to aid in showing
component locations.
All illustrations and photos are shown using
deenergized equipment.
Follow the appropriate safety precautions
while handling any of the equipment. Failure
to do so may result in death or serious injury.
!
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 because they vary greatly.
c. InStructIon BulletInS AvAIlABle electronIcAlly
Changes to the instruction bulletin may
be implemented at any time and without
notice. Go to powellind.com to ensure use
of the current instruction bulletin for Powell
equipment.
NOTICE
To contact the Powell Service Division call
1.800.480.7273 or 713.944.6900, or email
info@powellservice.com.
For specific questions or comments pertaining
to this instruction bulletin email
documents@powellind.com with the
Instruction Bulletin number in the subject line.
D. ASSocIAteD BulletInS
• 01.4IB.78000A PowlVac-ND® Metal-Clad
Switchgear
• 01.4IB.78200 PowlVac-NDAR® Arc Resistant
Switchgear
• 01.4IB.51808A Vacuum Type Remote
Racking Device (51897G29)
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Safety
01.4IB.77000B
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-ND® circuit breakers.
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.
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4Safety
01.4IB.77000B
PowlVac-ND® Vacuum Circuit Breaker
c. GenerAl
1. Only 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 the 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.
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Safety
01.4IB.77000B
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. Do not remove or deface any
of these warning/caution labels.
NOTICE
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6Equipment Description
01.4IB.77000B
PowlVac-ND® Vacuum Circuit Breaker
Ch 3 Equipment Description
A. GenerAl DeScrIptIon
Powell is committed to continuous product
improvement.
It is possible that improvements occurred
between revisions to this document and
therefore, may not be described in these
instructions. If the equipment does not
resemble the photographs and descriptions
contained herein, contact Powell before
attempting to perform any actions.
NOTICE
PowlVac-ND®Vacuum Circuit Breakers use
sealed vacuum interrupters (Figure 1, u)
to control the primary circuit. The primary
connections to the associated metal-clad
switchgear are made by parallel copper
busbars terminating in multiple contact fingers
of the primary disconnecting devices
(Figure 1, t & v). The primary disconnecting
devices, busbars, and vacuum interrupter
assemblies are supported by insulating
supports (Figure 1, q & r) specifically designed
for the application.
The primary current path side of the circuit
breaker is considered the rear of the circuit
breaker, while the side with the cover
containing the various indicators and manual
operators is considered the front of the circuit
breaker. By removing the front cover, the
operating mechanisms of the circuit breaker
are exposed. The stored energy mechanism
assembly provides motion to each of the
vacuum interrupter moving contact assemblies
through operating pushrods (Figure 1, ak). In
the same metal enclosed compartment as the
stored energy mechanism is the circuit breaker
racking mechanism and interlocks which
control the movement of the circuit breaker
between the test/disconnected and connected
positions. The racking mechanism (Figure 7)
provides the motion to engage/disengage the
primary disconnecting devices and to
open/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
by ten (10) cover bolts (Figure 1, a) that
may be removed, allowing access to the
stored energy mechanism and its interlocks,
auxiliary switches, racking mechanism, and
other control devices.
!
CAUTION
Prior to removing the front cover, ensure 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/close the stored
energy mechanism. The circuit breaker
nameplate (Figure 1, f) is also located on
the mechanism escutcheon. If for any
reason the escutcheon is removed from the
circuit breaker, it shall be verified that the
serial number contained on the nameplate
matches the engraved serial number plate
(Figure 1, y) permanently affixed to the
rear of the circuit breaker frame prior to
installing the escutcheon.
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Equipment Description
01.4IB.77000B
The mechanism employed in the circuit
breaker is a stored energy system which
uses a charging motor to compress the
main closing spring. During the closing
operation the energy stored in the main
closing spring is released. This 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, g), located
on the bottom right of the mechanism
compartment, is assembled to the circuit
breaker by a cover plate which is bolted to
the circuit breaker right frame side sheet.
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 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 2, n). The drive pawl,
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 adjustable
by the holding pawl adjusting eccentric
(Figure 2, aa) 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.
The ratchet wheel (Figure 2, q) 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 2, ab). Crank pins
(Figure 2, ac) are assembled to the crank
arms, which 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 will drive 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 will overcome 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 2, r) and the motor cutoff switch is
operated.
The motor cutoff switch (Figure 2, k),
located at the right of the mechanism, is
operated by the spring charge indicator
and motor cutoff cam (Figure 2, h). The
spring charge indicator (Figure 1, m) will
display that the mechanism is charged.
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8Equipment Description
01.4IB.77000B
PowlVac-ND® Vacuum Circuit Breaker
Figure 1 PowlVac-ND Circuit Breaker - Exterior View
a. Cover Bolts
b. Front Cover
c. Breaker Position Indicator
d. Padlock Provision - Stationary Clip
e. Padlock Provision - Movable Arm
f. Nameplate
g. Manual Trip Operator
h. Manual Charging Crank
i. Circuit Breaker Open/Closed Indicator
j. Manual Close Operator
k. Secondary Disconnect Receptacle
l. Operations Counter
m. Spring Charge Indicator
n. Secondary Disconnect Guide Sleeve
o. Anti-Rollout Latch
p. MOC Actuator
q. Standoff Insulator
r. Vacuum Interrupter Support
s. TOC Acutator
t. Upper Primary Disconnecting Device
u. Vacuum Interrupter
v. Lower Primary Disconnecting Device
w. Frame
x. Ground Connection
y. Serial Number Plate Location
z. Wheel
aa. Crank Arm Roller
ab. Racking Crank Arm
ac. Worm Gear
ad. Racking Drive Shaft Extention
ae. Operating Pin
af. Bell Crank
ag. Jackshaft Pin
ah. Lock Nut
ai. Spring Yoke
aj. Contact Loading Spring
ak. Operating Pushrod
w
v
u
t
aeaf
ag
ak aj ai
ah
ab
ad
ac
aa
a
mn
k
i
e
d
c
j
h
f
b
g
l
o
x
srp
y
q
z
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Equipment Description
01.4IB.77000B
Figure 2 PowlVac-ND® Circuit Breaker - Interior View
a. Main Closing Spring
b. Anti-Pump Relay
c. Connecting Rod
d. Primary Shunt Trip Coil
e. Shock Asorber (Dashpot)
f. Auxiliary Switch
g. Charging Motor
h. Motor Cutoff Cam
i. Close Bar Adjusting Screw
j. Charging Motor Drive Shaft
k. Motor Cutoff Switch
l. Secondary Trip Prop
m. Main Cam Roller
n. Camshaft
o. Main Closing Cam
p. Reset Spring
q. Ratchet Wheel
r. Pawl Lift Plate
s. Close Latch Arm
t. Drive Pawl
u. Close Latch Shaft
v. Pawl Support Arm
w. Latch Check Switch
x. Secondary Trip Prop Adjusting Screw
y. Jackshaft
z. Holding Pawl Support Arm
aa. Holding Pawl Adjusting Eccentric
ab. Crank Arm
ac. Crank Pin
ad. Closing Coil
b
a
c
g
f
e
d
ad
n
m
l
o
p
aa
z
x
ac
ab
y
w
q
s
u
v
t
r
j
k
i
h
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10 Equipment Description
01.4IB.77000B
PowlVac-ND® Vacuum Circuit Breaker
Figure 3 Cam and Fundamental Linkage Positions
a) Breaker Open - Spring Charged - Links Reset b) Breaker Closed - Spring Discharged
c) Breaker Open - Spring Discharged d) Breaker Closed - Spring Charged
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Equipment Description
01.4IB.77000B
Figure 4 Mechanism and Trip Linkages
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
l
c
b
d
e
f
g
h
i
j
k
a
m
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12 Equipment Description
01.4IB.77000B
PowlVac-ND® Vacuum Circuit Breaker
The camshaft would continue to rotate,
except that it is restrained by the close latch
arm (Figure 2, s) engaging against the close
latch shaft (Figure 2, u). 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.
The close latch, when released either by the
closing coil or the manual close operator,
allows the main closing spring to pull the
crank arms upward thus rotating the main
closing cam and driving the fundamental
linkage into the closed position. This
causes the main linkage to rotate the
jackshaft such that the operating pushrods
are driven toward the current carrying side
of the circuit breaker.
Each operating pushrod assembly has a
recess at each end which encloses a contact
loading spring (Figure 1, aj). At the end of
this spring is a spring yoke (Figure 1, ai),
which connects with bell cranks. The spring
yoke is restrained by a lock nut on a stud
which passes through the contact loading
spring and is attached to the operating
pushrod assembly. The contact loading
spring has initial compression such that as
soon as the vacuum interrupter contacts
touch, the springs are preloaded to a value
sufficient to resist vacuum interrupter
contact separation under the highest
electromagnetic forces exerted by the rated
short-circuit current. Further movement
of the operating pushrod assembly
compresses the contact loading spring
even more and produces a gap between
the face of the spring yoke and the lock nut.
For each phase, bell cranks (Figure 1, af) are
located on the outside of the lower
primary disconnecting devices
(Figure 1, v) and are supported by bearings.
Each bell crank is connected to an
operating pin, which passes through a slot
in the lower primary disconnecting devices
and engage an extension to the vacuum
interrupter assembly thus moving the
vacuum interrupter contact. The bell cranks
give an approximate 3 to 1 multiplication
of the contact loading spring force,
enabling a lower spring rate to be used.
It also multiplies the contact movement
by a factor of approximately 3, so that the
mechanism linkages have relatively large
movements and are less critical.
In the cam and fundamental linkage
positions (Figure 3, b & d), the contact
loading springs and the main opening
springs are both acting to compress the
three (3) main mechanism links. The
jackshaft extends from the left to the right
side of the circuit breaker frame and is
supported at the main circuit breaker frame
side sheets and by the mechanism side
sheets. The outer operating levers on the
jackshaft have connections to the circuit
breaker auxiliary switch and MOC operating
linkage.
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