Safety POWELL PowlVac-ND 4 Series Training manual

Instruction Bulletin - 01.4IB.77020
PowlVac-ND® and PowlVac-NDA™ Series 4
Vacuum Circuit Breakers
5kV / 1200A & 2000A / 36kA & 50kA
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01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
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Contact Information
Powell Electrical Systems, Inc.
powellind.com
[e-mail]
Service Division
7232 Airport Blvd.
Houston, Texas 77061
713.944.6900 phone
713.948.4569 fax

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01.4IB.77020
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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”, “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.

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01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
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01.4IB.77020
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 ............................................................................................................................................................16
c. rAckInG MechAnISM for poWlvAc-nD®SerIeS 4 cIrcuIt BreAker ........................................................................ 17
1) General Description ..............................................................................................................................................................17
2) Closed Door Racking Mechanism .....................................................................................................................................19
D. AutoMAtIc rAckInG MechAnISM for poWlvAc-nDA™ SerIeS 4 cIrcuIt BreAker .................................................... 20
1) General Description ..............................................................................................................................................................20
2) Racking Mechanism .............................................................................................................................................................21
e. cIrcuIt BreAker coMpArtMent InterfAceS .......................................................................................................... 22
1) Primary Disconnecting Devices .........................................................................................................................................22
2) Secondary Disconnecting Devices ....................................................................................................................................22
3) MOC (Mechanism Operated Cell Switch) Actuator .......................................................................................................22
4) TOC (Truck Operated Cell Switch) Actuator ....................................................................................................................22
5) Ground Connection ..............................................................................................................................................................22
6) Shutter Rollers ........................................................................................................................................................................23
7) Anti-Rollout Latch .................................................................................................................................................................23
f. vAcuuM InterrupterS ....................................................................................................................................... 23
G. vAcuuM Interrupter connectIonS ..................................................................................................................... 23

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01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
Contents
Ch 4 Installation .............................................................................................................24
A. receIvInG ........................................................................................................................................................ 24
B. hAnDlInG ....................................................................................................................................................... 24
c. StorAGe ......................................................................................................................................................... 25
D. plAcInG the cIrcuIt BreAker Into ServIce ........................................................................................................... 26
1) High Voltage Insulation Integrity ......................................................................................................................................26
2) Vacuum Integrity ...................................................................................................................................................................27
3) Control Voltage Insulation Integrity .................................................................................................................................28
4) Mechanical Operation Check .............................................................................................................................................29
5) Electrical Operation Check ..................................................................................................................................................30
6) Emergency Racking Mechanism Check (PowlVac-NDA™Series 4 Circuit Breaker Only) .....................................30
e. rAckInG proceDureS for poWlvAc-nD®SerIeS 4 cIrcuIt BreAker ........................................................................ 31
1) Prior to Inserting the Circuit Breaker into the Circuit Breaker Compartment .........................................................32
2) Inserting the Circuit Breaker to the Test/Disconnected Position ................................................................................33
3) Inserting the Circuit Breaker to the Connected Position ..............................................................................................34
4) Removing the Circuit Breaker from the Connected to the Test/Disconnected Position .......................................35
5) Removing the Circuit Breaker from the Test/Disconnected Position out of the
Circuit Breaker Compartment ............................................................................................................................................36
6) Remote Racking .....................................................................................................................................................................36
f. rAckInG proceDureS for poWlvAc-nDA™ SerIeS 4 cIrcuIt BreAker .................................................................... 37
1) Prior to Inserting the Circuit Breaker into the Circuit Breaker Compartment .........................................................37
2) Inserting the Circuit Breaker to the Test/Disconnected Position ................................................................................38
3) Inserting the Circuit Breaker to the Connected Position ..............................................................................................39
4) Emergency Racking In Procedure ......................................................................................................................................39
4) Removing the Circuit Breaker from the Connected to the Test/Disconnected Position .......................................40
5) Removing the Circuit Breaker from the Test/Disconnected Position out of the
Circuit Breaker Compartment ............................................................................................................................................41
6) Emergency Racking Out Procedure ..................................................................................................................................41
Ch 5 Maintenance ..........................................................................................................43
A. GenerAl DeScrIptIon ....................................................................................................................................... 43
1) Introduction ............................................................................................................................................................................43
2) Inspection and Cleaning ......................................................................................................................................................44
B. MechAnISM AreA ............................................................................................................................................. 45
1) Mechanical Operation .........................................................................................................................................................45
2) Lubrication ..............................................................................................................................................................................45
3) Closing Spring Removal .......................................................................................................................................................49
4) Slow Closing of Mechanism ................................................................................................................................................50
5) Mechanism Adjustments .....................................................................................................................................................50
6) Electrical Operation ..............................................................................................................................................................55

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01.4IB.77020
c. vAcuuM Interrupter AnD contAct AreA ............................................................................................................ 55
1) Vacuum Interrupter and Contact Erosion .......................................................................................................................55
2) Sliding Contact Finger Wear ...............................................................................................................................................56
3) Vacuum Integrity ...................................................................................................................................................................56
4) Mechanical Adjustment of Vacuum Interrupters ................................................................................................................56
D. optIonAl MAIntenAnce proceDureS .................................................................................................................. 56
1) High Potential Tests ..............................................................................................................................................................56
2) Timing .....................................................................................................................................................................................57
3) Primary Resistance Check ...................................................................................................................................................57
Ch 6 Recommended Renewal Parts and Replacement Procedures ..............................58
A. orDerInG InStructIonS ..................................................................................................................................... 58
B. recoMMenDeD reneWAl pArtS .......................................................................................................................... 58
c. replAceMent proceDureS ................................................................................................................................. 58
1) Vacuum Interrupter Assembly ............................................................................................................................................59
2) Closing Coil Assembly ...........................................................................................................................................................59
3) Primary Shunt Trip Coil Assembly ......................................................................................................................................59
4) Secondary Shunt Trip Coil Assembly .................................................................................................................................59
5) Undervoltage Device Assembly .........................................................................................................................................59
6) Charging Motor Assembly ..................................................................................................................................................59
7) Anti-Pump Relay Assembly .................................................................................................................................................59
8) Latch Check Switch ...............................................................................................................................................................59
9) Motor Cutoff Switch Assembly ...........................................................................................................................................59
10) Auxiliary Switch .....................................................................................................................................................................59
Contents

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iv
01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
Figures
Figure 1 Typical PowlVac-ND®Series 4 Vacuum Circuit Breaker .................................8
Figure 2 Typical PowlVac-NDA™Series 4 Vacuum Circuit Breaker .............................8
Figure 3 PowlVac-NDA™Circuit Breaker - Exterior View .............................................9
Figure 4 PowlVac-NDA™Circuit Breaker - Interior View ............................................10
Figure 5 Cam and Fundamental Linkage Positions ...................................................11
Figure 6 Mechanism and Trip Linkages .....................................................................12
Figure 7 Operation Sequence ....................................................................................14
Figure 8 Typical Control Scheme ................................................................................15
Figure 9 Closed Door Racking Mechanism and Interlock .........................................19
Figure 10 Circuit Breaker in Shipping Carton ..............................................................24
Figure 11 Circuit Breaker on Crane ..............................................................................25
Figure 12 Secondary Disconnect Device ......................................................................34
Figure 13 Racking Handle Insertion ............................................................................34
Figure 14 Circuit Breaker Anti-Rollout Latch ...............................................................36
Figure 15 Lubrication ...................................................................................................47
Figure 16 Lubrication (cont) .........................................................................................48
Figure 17 Main Closing Spring Assembly Installed .....................................................49
Figure 18 Main Closing Spring Assembly Compressed for Removal ...........................49
Figure 19 Primary & Secondary Trip Prop Adjustment ...............................................51
Figure 20 Feeler Gauge ................................................................................................52
Figure 21 Latch Check Switch Adjustment ...................................................................53
Figure 22 Measurement of Open Position ...................................................................55
Figure 23 Measurement of Closed Position .................................................................55
Figure 24 Primary Current Path ...................................................................................60
Figure 25 Control Devices ............................................................................................62
Tables
Table A Field Dielectric Test Values .................................................................................26
Table B Lubrication .........................................................................................................46
Table C Timing .................................................................................................................57
Table D Primary Resistance .............................................................................................57
Table E Primary Current Path ..........................................................................................60
Table F Control Devices ...................................................................................................61
Table G Miscellaneous Parts ...........................................................................................63

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01.4IB.77020
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General Information
01.4IB.77020
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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2General Information
01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
A. Scope
This instruction bulletin is intended to assist
users in the design and safe operation of
these PowlVac-ND® and PowlVac-NDA™ circuit
breakers:
• 05PV36SNDX-4, 1200 & 2000A
• 05PV50SNDX-4, 1200 & 2000A
• 05PV36SNDM-4, 1200 & 2000A
• 05PV50SNDM-4, 1200 & 2000A
• 05PV36NDAX-01 (24-pin; out of production)
• 05PV36NDAX-4, 1200 & 2000A
• 05PV50NDAX-4, 1200 & 2000A
• 05PV36NDAM-4, 1200 & 2000A
• 05PV50NDAM-4, 1200 & 2000A
B. purpoSe
The information in this instruction bulletin
is intended to provide the details 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
[email protected]om.
For specific questions or comments pertaining
to this instruction bulletin email
[e-mail] 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)
• 01.4IB.49001 PowlVac® Series 4 Test Cabinet

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Safety
01.4IB.77020
NException No. 1: An adequately rated
permanently mounted test device shall be
permitted to be used to verify the absence of
voltage of the conductors or circuit parts at
the work location, provided it meets the all
following requirements: (1) It is permanently
mounted and installed in accordance with
the manufacturer’s instructions and tests
the conductors and circuit parts at the point
of work; (2) It is listed and labeled for the
purpose of verifying the absence of voltage;
(3) It tests each phase conductor or circuit
part both phase-to-phase and phase-to-
ground; (4) The test device is verified as
operating satisfactorily on any known voltage
source before and after verifying the absence
of voltage.
NException No. 2: On electrical systems over
1000 volts, noncontact test instruments shall
be permitted to be used to test each phase
conductor.
Informational Note No. 1: See UL 61010-1,
Safety Requirements for Electrical Equipment
for Measurement, Control, and Laboratory
Use, Part 1: General Requirements, for
rating, overvoltage category, and design
requirements for voltage measurement
and test instruments intended for use on
electrical system 1000 volts and below.
N Informational Note No. 2: For additional
information on rating and design
requirements for voltage detectors, refer
to IEC 61243-1, Live Working - Voltage
Detectors - Part 1: Capacitive type to be used
for voltages exceeding 1kV a.c., or IEC 61243-
2, Live Working - Voltage Detectors - Part 2:
Resistive type to be used for voltages of 1kV
to 36kV a.c., or IEC 61243-3, Live Working -
Voltage Detectors - Part 3: Two-pole voltage
type.
Ch 2 Safety
A. SAfe Work conDItIon
The information in Section A is quoted from
NFPA 70E 2018 - Article 120, 120.5 Establishing an
Electrically Safe Work Condition.
120.5 Process or Establishing and Verifying an
Electrically Safe Work Condition. Establishing
and verifying an electrically safe condition shall
include all of the following steps, which shall be
performed in the order presented, if feasible:
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. Release stored electrical energy.
5. Release or block stored mechanical energy.
6. Apply lockout/tagout devices in accordance
with a documented and established
procedure.
7. Use an adequately rated portable test
instrument to test each phase conductor or
circuit part to verify it is de-energized. Test
each phase conductor or circuit part both
phase-to-phase and phase-to-ground.
Before and after each test, determine
that the test instrument is operating
satisfactorily through verification on any
known voltage source.

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4Safety
01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
8. 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 de-energized
could contact other exposed energized
conductors or circuit parts, apply temporary
protective grounding equipment in
accordance with the following:
a.. Placement. Temporary protective
grounding equipment shall be placed
at such locations and arranged in such
a manner as to prevent each employee
from being exposed to a shock hazard
(i.e., hazardous differences in electrical
potential). The location, sizing, and
application of temporary protective
grounding equipment shall be
identified as part of the employer’s job
planning.
b. Capacity. Temporary protective
grounding equipment shall be capable
of conducting the maximum fault
current that could flow at the point of
grounding for the time necessary to
clear the fault.
N Informational Note: ATSM F855, Standard
Specification for Temporary Protective
Grounds to be Used on De-energized Electric
Power Lines and Equipment, is an example
of a standard that contains information on
capacity of temporary protective grounding
equipment.
c. Impedance. Temporary protective
grounding equipment and connections
shall have an impedance low enough
to cause immediate operation
of protective devices in case of
unintentional energizing of the electric
conductors or circuit parts.
B. SAfety GuIDelIneS
Study this instruction bulletin and all other
associated documentation before uncrating
the equipment.
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®and PowlVac-NDA™Series 4 circuit
breakers.

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Safety
01.4IB.77020
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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6Equipment Description
01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
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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Equipment Description
01.4IB.77020
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® Series 4 (Figure 1) and
PowlVac-NDA™ Series 4 (Figure 2) Vacuum
Circuit Breakers use sealed vacuum interrupters
(Figure 3, v) 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 3, u & w). The primary disconnecting
devices, busbars, and vacuum interrupter
assemblies are supported by insulating
supports (Figure 3, r & s) 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 3, al). 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 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 3, 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 3, g) 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 3, z) permanently affixed to the
rear of the circuit breaker frame prior to
installing the escutcheon.

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8Equipment Description
01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
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 4, m), 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 4, k). 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 4, t) 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 4, v) 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 4, u). Crank pins
(Figure 4, s) are assembled to the crank
arms, which point outward. The crank arms
engage the bottom ends of the connecting
rods (Figure 4, 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 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 4, w) and the motor cutoff switch is
operated.
The motor cutoff switch (Figure 4, af),
located at the right of the mechanism, is
operated by the spring charge indicator
and motor cutoff cam (Figure 4, ac). The
spring charge indicator (Figure 3, o) will
display that the mechanism is charged.

Powered by Safety®9
Equipment Description
01.4IB.77020
Figure 1 Typical PowlVac-ND®Series 4 Vacuum Circuit Breaker
Figure 2 Typical PowlVac-NDA™Series 4 Vacuum Circuit Breaker

Powered by Safety®
10 Equipment Description
01.4IB.77020
PowlVac-ND®and PowlVac-NDA™Series 4
Vacuum Circuit Breakers
Figure 3 PowlVac-NDA™Circuit Breaker - Exterior View
a. Cover Bolts
b. Emergency Racking Drive Shaft Shutter
c. Circuit Breaker Monitor IR Window
d. Padlock Seal
e. Breaker Position Indicator
f. Front Cover
g. Nameplate
h. Manual Trip Operator
i. Manual Charging Crank
j. Circuit Breaker Open/Closed Indicator
k. Secondary Disconnect Latch
l. Manual Close Operator
m. Secondary Disconnect Receptacle
n. Operations Counter
o. Spring Charge Indicator
p. Anti-Rollout Latch
q. MOC Actuator
r. Standoff Insulator
s. Vacuum Interrupter Support
t. TOC Actuator
u. Upper Primary Disconnecting Device
v. Vacuum Interrupter
w. Lower Primary Disconnecting Device
x. Frame
y. Ground Connection
z. Serial Number Plate Location
aa. Wheel
ab. Crank Arm Roller
ac. Racking Shaft
ad. Racking Crank Arm
ae. Manual Trip Lever
af. Operating Pin
ag. Bell Crank
ah. Jackshaft Pin
ai. Lock Nut
aj. Spring Yoke
ak. Contact Loading Spring
al. Operating Pushrod
x
w
v
u
afag
ah
al ak aj
ai
ac
ae
ab
ad
y
t
sq
z
r
aa
a
on
k
j
f
de
l
i
g
b
c
h
m
p

Powered by Safety®11
Equipment Description
01.4IB.77020
a
c
b
nm
i
h
k
f
g
j
l
e
d
Figure 4 PowlVac-NDA™Circuit Breaker - Interior View
a. Racking Motor
b. Circuit Breaker Monitor™
(Optional)
c. Main Closing Spring
d. Anti-Pump Relay
e. Connecting Rod
f. Primary Shunt Trip Coil
g. Shock Absorber (Dashpot)
h. Secondary Trip Prop
i. Main Cam Roller
j. Reset Spring
k. Camshaft
l. Main Closing Cam
m. Charging Motor
n. Auxiliary Switch
o. Latch Check Switch
p. Secondary Trip Prop Adjusting Screw
q. Jackshaft
r. Holding Pawl Support Arm
s. Crank Pin
t. Holding Pawl Adjusting Eccentric
u. Crank Arm
v. Ratchet Wheel
w. Pawl Lift Drive Plate
x. Close Latch Arm
y. Close Latch Shaft
z. Drive Pawl
aa. Closing Coil
ab. Pawl Support Arm
ac. Motor Cutoff Cam
ad. Close Bar Adjusting Screw
ae. Charging Motor Drive Shaft
af. Motor Cutoff Switch
op
rq
s
u
w
z
ab
t
v
x
y
aa
ac
ae
ad
af