Siemens 3AH Owner's manual

Medium-Voltage
Equipment
Vacuum Circuit Breaker
Operator Module
Type 3AH
4.16kV to 38kV
Instructions
Installation
Operation
Maintenance
SGIM-9918D

IMPORTANT
The information contained herein is general in nature and not intended for
specific application purposes. It does not relieve the user of responsibility to
use sound practices in application, installation, operation, and maintenance
of the equipment purchased. Siemens reserves the right to make changes in
the specifications shown herein or to make improvements at any time without
notice or obligations. Should a conflict arise between the general information
contained in this publication and the contents of drawings or supplementary
material or both, the latter shall take precedence.
Hazardous voltages and high-speed moving parts.
Will cause death, serious personal injury or
equipment damage.
De-energize and ground the equipment before main-
tenance. Maintenance should be performed only by
qualified personnel.
Unauthorized parts should not be used in the repair of
the equipment.
Follow all safety instructions contained herein.
SUMMARY
These instructions do not purport to cover all details or variations in equip-
ment, nor to provide for every possible contingency to be met in connection
with installation, operation, or maintenance. Should further information be
desired or should particular problems arise which are not covered sufficiently
for the purchaser’s purposes, the matter should be referred to the local sales
office.
The contents of this instruction manual shall not become part of or modify any
prior or existing agreement, commitment or relationship. The sales contract
contains the entire obligation of Siemens Energy, Inc. The warranty contained
in the contract between the parties is the sole warranty of Siemens Energy,
Inc. Any statements contained herein do not create new warranties or modify
the existing warranty.
QUALIFIED PERSON
For the purpose of this manual a qualified person is one who is familiar
with the installation, construction or operation of the equipment and the
hazards involved. In addition, this person has the following qualifications:
(a) is trained and authorized to de-energize, clear, ground, and tag circuits
and equipment in accordance with established safety practices.
(b) is trained in the proper care and use of protective equipment such as
rubber gloves, hard hat, safety glasses or face shields, flash clothing, etc.,
in accordance with established safety practices.
(c) is trained in rendering first aid.

Table of Contents ...................................................................1
Table of Illustrations ..............................................................2
Introduction and Safety ........................................................3
Introduction ...............................................................................3
Qualified Person ........................................................................3
Signal Words .............................................................................3
Dangerous Procedures ..............................................................3
Field Service Operation .............................................................3
Receiving, Handling and Storage .........................................4
Introduction ...............................................................................4
Receiving Procedure .................................................................4
Shipping Damage Claims (when applicable) ............................4
Handling Procedure ..................................................................4
Storage Procedure ....................................................................4
Installation Checks and Initial Functional Tests ..................5
Introduction ...............................................................................5
Inspections, Checks andTests without Control Power .............5
Spring Discharge Check (Figure 1) ............................................5
Manual Spring Charging Check ................................................5
As-Found and Vacuum CheckTests ...........................................5
Automatic Spring Charging Check ............................................5
Final Mechanical Inspections without Control Power ...............5
Vacuum Interrupter/Operator Description ..........................6
Introduction ...............................................................................6
Vacuum Interrupters .................................................................7
Primary Disconnects (Figure 4) .................................................7
Phase Barriers ..........................................................................7
Stored Energy Operating Mechanism ......................................7
Vacuum Interrupter/Operator Module .....................................7
Construction (Figures 1, 2, 5, 6a,and 6b) ..................................8
Circuit Breaker Pole (Figure 5) ..................................................8
Current-Path Assembly (Figure 5) ............................................8
Vacuum Interrupter (Figure 5) ..................................................8
Switching Operation (Figure 5 and 6a) ....................................8
Operating Mechanism .............................................................8
Construction ........................................................................... 11
Motor Operating Mechanism (Figure 6a) ................................11
Mode of Operation ..................................................................11
Charging ..................................................................................11
Closing (Figures 6a, 6b and 7a - 7d) ........................................11
Trip Free Operation (Figures 6a and 6b) ..................................11
Opening (Figure 6a) ................................................................ 11
Rapid Auto-Reclosing ..............................................................15
Manual Operation ...................................................................15
Manually Charging the Closing Spring (Figures 9a and 9b) ....15
Manual Closing (Figure 6a) .....................................................15
Manual Opening (Figure 6a) ....................................................15
Close coil (52SRC) ...................................................................17
Trip coil (52T) ...........................................................................17
Indirect Releases (Secondary Shunt Release
(DualTrip) (52T1) or Undervoltage (27)).............................. 17
Secondary Shunt Release (52T1) (Figure 11) ......................... 17
Undervoltage Release (27) (Figures 10 and 11) ..................... 17
Construction and Mode of Operation of Secondary Shunt
Release and Undervoltage Release
(Figures 11, 12 and 13) ....................................................... 17
CapacitorTrip Device ...............................................................18
Shock Absorber .......................................................................18
Auxiliary Switch (52a/b) ..........................................................18
Spring Charging Motor (88) ....................................................18
Cover SGIM-9918-01
Table of Contents
1
Maintenance .........................................................................19
Introduction and Maintenance Intervals ..................................19
Recommended HandTools .......................................................19
Recommended Maintenance and Lubrication .........................19
Checks of the Primary Power Path ...........................................20
Cleanliness Check ....................................................................20
Inspection of Flexible Connectors ............................................20
Checks of the Stored Energy Operator Mechanism ................20
Maintenance and Lubrication ..................................................20
Fastener Check .........................................................................22
Manual Spring Charging and Contact Erosion Checks ............22
Electrical Control Checks ..........................................................23
Check of the Wiring andTerminals ...........................................23
Automatic Spring Charging Check
(Control Power Required) ......................................................23
Electrical Close andTrip Check
(Control Power Required) ......................................................25
Checks of the Spring Charging Motor (88) ...............................25
Vacuum Interrupters .................................................................25
Vacuum Integrity Check (using MechanicalTest) (Figure 18)....25
High-PotentialTests ..................................................................25
Vacuum Integrity Check (using DielectricTest) .........................25
High PotentialTest Voltages .....................................................25
Vacuum IntegrityTest Procedure ..............................................26
As-Found Insulation and Contact ResistanceTests .................26
Insulation and Contact ResistanceTest Equipment .................26
Insulation and Contact ResistanceTest Procedure ..................27
Inspection and Cleaning of Circuit Breaker Insulation .............27
FunctionalTests ........................................................................27
Overhaul ................................................................................28
Introduction ..............................................................................28
Circuit Breaker Overhaul ..........................................................28
Replacement at Overhaul ........................................................28
Replacement of Vacuum Interrupters ......................................28
Hydraulic Shock Absorber ........................................................31
Maintenance andTroubleshooting .....................................32
Appendix ...............................................................................35
Vacuum Circuit Breaker Operator Module

Figures
Figure 1 Front Panel Controls of Circuit Breaker
and Manual Charging of Closing Spring ............. 5
Figure 2 Vacuum Circuit Breaker Module .......................... 6
Figure 3 CutawayView of Vacuum Interrupter .................. 7
Figure 4 Vacuum Interrupter/Operating
Mechanism Module ............................................ 7
Figure 5 Pole Assembly ..................................................... 8
Figure 6a Stored Energy Operating Mechanism ...................... 9
Figure 6b Stored Energy Operating Mechanism ..................... 10
Figure 7a-b Operating Mechanism Section Diagram .............. 12
Figure 7c-d Operating Mechanism Section Diagram .............. 13
Figure 8 Operator Sequential Operation Diagram ............ 14
Figure 9a-b Use of Manual Spring Charging Crank ................ 15
Figure 10Typical Elementary Diagram ..................................... 16
Figure 11 Construction of Secondary Shunt Release .............. 17
Figure 12 Latch Details ............................................................ 18
Figure 13 Undervoltage Locked/Unlocked Selection .............. 18
Figure 14 CapacitorTrip Device ............................................... 18
Figure 15 Operator Lubrication Points ..................................... 21
Figure 16 Contact Erosion Check Mark ................................... 22
Figure 17Typical Vacuum Interrupter Contact Life Curves .......24
Figure 18 Circuit Breaker Pole Assembly/Vacuum Check
Mechanical/Contact ResistanceTest ................ 26
Figure 19 Vacuum Interrupter Replacement Illustration ......... 29
Figure 20Technique forTighteningVacuum Interrupter
Terminal Clamp Hardware................................. 30
Table of Illustrations
2
Tables
Table 1 MaintenanceTasks ............................................ 20
Table 2 Maintenance and Lubrication Intervals
(ANSI C37.06) .................................................... 20
Table 3 Typical Vacuum Interrupter Contact
Life Expectancy ................................................. 23
Table 4 High PotentialTest Voltages .............................. 25
Table 5 Maximum Contact Resistance .......................... 27
Table 6 Overhaul Schedule ............................................ 28
Table 7 Vacuum Interrupter Stroke ............................... 32
Table 8 Troubleshooting .............................................. 33-34
Appendix
Table A-1a 3AH Circuit Breaker Ratings
(Historic “Constant MVA” Rating Basis) ..................... 35
Table A-1b 3AH Circuit Breaker Ratings
(New “Constant kA” Rating Basis) .............................. 36
Table A-2 3AH Circuit Breaker Ratings ................................... 37
Table A-3 Interrupting Capacity of Circuit Breaker
Auxiliary Switch Contacts ........................................... 37
Table A-4 Circuit BreakerWeights .......................................... 37
Vacuum Circuit Breaker Operator Module

Hazardous voltages and high-speed
moving parts.
Will cause death, personal injury or
property damage.
Only qualified persons thoroughly familiar
with the equipment, instruction manuals and
drawings should install, operate and/or main-
tain this equipment.
Introduction and Safety
Introduction
The 3AH family of vacuum circuit breakers is designed to
meet all the applicable ANSI, NEMA and IEEE standards.
Successful application and operation of this equipment de-
pends as much upon proper installation and maintenance by
the user as it does upon the careful design and fabrication
by Siemens.
The purpose of this Instruction Manual is to assist the user
in developing safe and efficient procedures for the installa-
tion, maintenance and use of the equipment.
NOTE: IEEE Standards Requirements for Conversion of
Power Switchgear Equipment (C37.59); Siemens has devel-
oped instruction manuals for particular replacement circuit
breaker drawout vehicles, consult factory.
Contact the nearest Siemens representative if any additional
information is desired.
Qualified Person
For the purpose of this manual a Qualified Person is one
who is familiar with the installation, construction or opera-
tion of the equipment and the hazards involved. In addition,
this person has the following qualifications:
•Training and authorization to energize, de-energize, clear,
ground and tag circuits and equipment in accordance
with established safety practices.
•Training in the proper care and use of protective equip-
ment such as rubber gloves, hard hat, safety glasses, face
shields, flash clothing, etc., in accordance with estab-
lished safety procedures.
•Training in rendering first aid.
Signal Words
The signal words “Danger”, “Warning” and “Caution” used
in this manual indicate the degree of hazard that may be
encountered by the user. These words are defined as:
Danger - Indicates an imminently hazardous situation
which, if not avoided, will result in death or serious
injury.
Warning - Indicates a potentially hazardous situation
which, if not avoided, could result in death or serious
injury.
Caution - indicates a potentially hazardous situation
which, if not avoided, may result in minor or moderate
injury.
Dangerous Procedures
In addition to other procedures described in this manual as
dangerous, user personnel must adhere to the following:
1. Always work on de-energized equipment. Always de-ener-
gize a circuit breaker, and remove it from the switchgear
before performing any tests, maintenance or repair.
2. Always perform maintenance on the circuit breaker after
the spring-charged mechanisms are discharged.
3. Always let an interlock device or safety mechanism per-
form its function without forcing or defeating the device.
Field Service Operation
Siemens can provide competent, well-trained Field Service
Representatives to provide technical guidance and advisory
assistance for the installation, overhaul, repair and main-
tenance of Siemens equipment, processes and systems.
Contact regional service centers, sales offices or the factory
for details, or telephone Siemens Field Service at
1-800-241-4953.
3

Heavy weight. Can cause death, serious
injury, or property damage.
Use of a qualified rigger to hoist the circuit
breaker.
Receiving, Handling and Storage
Introduction
This manual covers the Receiving, Handling and Storage
instructions forType 3AH vacuum circuit breakers shipped
separately from the switchgear. This section of the manual
is intended to help the user identify, inspect and protect the
circuit breaker prior to its installation.
Receiving Procedure
Make a physical inspection of the shipping container before
removing or unpacking the circuit breaker. Check for ship-
ment damage or indications of rough handling by the carrier.
Check each item against the manifest to identify any short-
ages.
Accessories such as the manual charging crank, the racking
crank and the split plug jumper are shipped separately.
Shipping Damage Claims (when applicable) - Follow normal
shipment damage procedures, which should include:
1. Check for visible damage upon arrival.
2. Visible damage must be noted on delivery receipt, and
acknowledged with driver’s signature. Notation, “Pos-
sible internal damage, subject to inspection” must be on
delivery receipt.
3. Notify the Siemens Sales office immediately of any ship-
ment damage.
4. Arrange for carrier’s inspection. Do not move the unit
from its unloading point.
Handling Procedure
1. Carefully remove the shipping carton from the circuit
breaker. Keep the shipping pallet for later use if the cir-
cuit breaker is to be stored prior to its installation.
2. Inspect for concealed damage. Notification to carrier must
take place within 15 days to assure prompt resolution of
claims.
3. Each circuit breaker should be appropriately lifted to
avoid crushing the side panels of the circuit breaker, or
damaging the primary disconnect subassemblies.
Circuit breaker weights (Table A-4).
4.The palleted circuit breaker can also be moved using a
properly rated fork-lift vehicle. The pallets are designed
for movement by a standard fork-lift vehicle.
Storage Procedure
1. When the circuit breaker will be placed on its pallet for
storage, be sure the unit is securely bolted to the pallet
and covered with polyethylene film at least 10 mils thick.
Indoor Storage - Whenever possible, store the circuit breaker
indoors. The storage environment must be clean, dry and
free of such items as construction dust, corrosive atmo-
sphere, mechanical abuse and rapid temperature variations.
Outdoor Storage - Outdoor storage is not recommended.
When no other option is available, the circuit breaker must
be completely covered and protected from rain, snow, dirt
and all other contaminants.
Space Heating - Space heating must be used for both indoor
and outdoor storage to prevent condensation and corrosion.
When stored outdoors, 250 watts per circuit breaker of space
heating is recommended.
4

Figure 1. Front Panel Controls of Circuit Breaker and
Manual Charging of Closing Spring
Hazardous voltages and high-speed
moving parts.
Will cause death, severe personal injury, or
property damage.
Read instruction manuals, observe safety
instructions and use qualified personnel.
Installation Checks and Initial FunctionalTests
Introduction
This section provides a description of the inspections,
checks and tests to be performed on the circuit breaker
module only.
Inspections, Checks and Tests without Control Power
Vacuum circuit breakers are normally shipped with their
primary contacts open and their springs discharged. How-
ever, it is critical to first verify the discharged condition of
the spring-loaded mechanisms after de-energizing control
power.
Spring Discharge Check (Figure 1)
Perform the Spring Discharge Check before removing
the circuit breaker from the pallet or removing it from the
switchgear.
The spring discharge check consists of simply performing
the following tasks in the order given. This check assures
that both the opening and closing springs are fully dis-
charged.
1. Press red Open pushbutton.
2. Press black Close pushbutton.
3. Again press red Open pushbutton.
4. Verify Spring Condition Indicator shows DISCHARGED.
5. Verify Main Contact Status Indicator shows OPEN.
Manual Spring Charging Check
1. Insert the manual spring charging crank into the manual
charge handle socket as shown in Figure 1. Turn the
crank clockwise until the spring condition indicator
shows the closing spring is Charged.
2. Repeat the Spring Discharge Check.
3. Verify that the springs are discharged and the circuitbreak-
er primary contacts are open by indicator positions.
As-Found and Vacuum Check Tests - Perform and record the
results of both the As-Found insulation test and the vacuum
check high-potential test. Procedures for these tests are
described in the Maintenance Section of this manual.
Automatic Spring Charging Check
Note: A temporary source of control
power and test leads may be required if the control power
source has not been
connected to the switchgear. Refer to the specific wiring
information and rating label for your circuit breaker to de-
termine the voltage required and where the control voltage
signal should be applied. When control power is connected
to the circuit breaker, the closing spring should automati-
cally charge.
The automatic spring charging features of the circuit breaker
must be checked. Control power is required for automatic
spring charging to take place.
1. Open control power circuit by opening the control power
disconnect device.
2. Energize (close) the control power circuit disconnect.
3. Use the Close and Open controls (Figure 1) to first Close
and then Open the circuit breaker contacts. Verify
contact positions visually by observing the Open/Closed
indicator on the circuit breaker.
4. De-energize control power by repeating Step 1. Discon-
nect the plug jumper from the switchgear first and next
from the circuit breaker.
5. Perform the Spring Discharge Check again. Verify that
the closing spring is discharged and the primary con-
tacts of the circuit breaker are open.
Final Mechanical Inspections without Control Power
1. Make a final mechanical inspection of the circuit breaker.
Verify that the contacts are in the open position, and the
closing spring is discharged.
2. Verify mechanical condition of springs.
3. Check for loose hardware.
5

Figure 2. Vacuum Circuit Breaker Module
Vacuum Interrupter/Operator Description
Introduction
TheType 3AH vacuum circuit breaker operator is intended
for application in a drawout truck for use in medium voltage
metal-clad switchgear. The 3AH circuit breaker conforms
to the requirements of ANSI Standards, including C37.20.2,
C37.04, C37.06, C37.09 and C37.010.
The circuit breaker consist of three vacuum interrupters, a
stored energy operating mechanism, necessary electrical
controls and interlock devices, disconnect devices to
connect the circuit breaker to both primary and control
power and an operator housing. In a typical installation in
a drawout truck, insulating barriers are located between the
vacuum interrupters and along the sides.
This section describes the operation of each major subas-
sembly as an aid in the operation, installation, maintenance
and repair of the circuit breaker.
6

Figure 4. Vacuum Interrupter/Operating Mechanism Module
Figure 3. Cutaway View of Vacuum Interrupter
Vacuum Interrupter/Operator Description
7
Vacuum Interrupters
The operating principle of the vacuum interrupter is simple.
Figure 3 is a cutaway view of a typical vacuum interrupter.
The entire assembly is sealed after a vacuum is established.
The vacuum interrupter stationary contact is connected to
the pole head of the circuit breaker. The vacuum interrupter
movable contact is connected to the pole bottom and driv-
ing mechanism of the circuit breaker. The metal bellows
provide a secure seal around the movable contact, prevent-
ing loss of vacuum while permitting vertical motion of the
movable contact.
When the two contacts separate, an arc is initiated which
continues conduction up to the following current zero. At
current zero, the arc extinguishes and any conductive metal
vapor which has been created by and supported the arc
condenses on the contacts and on the surrounding vapor
shield. Contact materials and configuration are optimized to
achieve arc motion and to minimize switching disturbances.
Primary Disconnects (Figure 4)
Figure 4 illustrates the pad provision to accept the primary
disconnects. Each circuit breaker has three upper and three
lower primary disconnect pad provisions, to perform the
connection to the switchgear.
Bolting hardware is M12 x 1.75 grade 8.Torque M12 bolts to
52 ft/lbs (70 Nm).
Phase Barriers
Plates of glass polyester insulating material are attached to
the circuit breaker and provide suitable electrical insulation
between the vacuum interrupter primary circuits and the
cubicle.
Stored Energy Operating Mechanism
The stored energy operating mechanism of the circuit
breaker is an integrated arrangement of springs, coils and
mechanical devices designed to provide a number of critical
functions. The energy necessary to close and open the con-
tacts of the vacuum interrupters is stored in powerful open-
ing and closing springs. These springs are normally charged
automatically, but there are provisions for manual charging.
The operating mechanism that controls charging, closing
and tripping functions is fully trip-free, i.e., spring charging
does not automatically change the position of the primary
contacts, and the closing function may be overridden by the
tripping function at any time.
Vacuum Interrupter/Operator Module
The vacuum interrupter/operator module consists of the
three poles, each with its vacuum interrupters and primary
insulators, mounted on the common motor or manually
charged spring stored energy operating mechanism hous-
ing. This module is shown in Figure 4.

Figure 5. Pole Assembly
Vacuum Interrupter/Operator Description
Construction (Figures 1, 2, 5, 6a and 6b)
Each of the circuit breaker poles are fixed to the rear of the
operating mechanism housing by two cast-resin insulators.
The insulators also connect to the upper and lower pole
supports which in turn support the ends of the vacuum inter-
rupter. The pole supports are aluminum castings (1200A and
2000A) or copper castings (3000A). Primary stud extensions
may be attached directly to the upper and lower pole sup-
ports.
The energy-storing mechanism and all the control and
actuating devices are installed in the mechanism housing.
The mechanism is of the spring stored energy type and is
mechanically and electrically trip free.
The close-open indicator, closing spring charge indicator,
and the operation counter are located on the front of the
mechanism housing.
The control connector for the control and signalling cables is
a multi contact plug.
Circuit Breaker Pole (Figure 5)
The vacuum interrupter is rigidly connected to the pole head
by its post insulator. The lower part of the vacuum interrupt-
er is stabilized against lateral forces by a centering ring on
the pole bottom. The external forces due to switching opera-
tions and the contact pressure are absorbed by the struts.
Current-Path Assembly (Figure 5)
The current-path assembly consists of the pole head, the
stationary contact, and the moving contact, which is con-
nected to the pole bottom by a terminal clamp and a flexible
connector.
Vacuum Interrupter (Figure 5)
The moving contact motion is aligned and stabilized by a
guide bushing. The metal bellows follows the travel of the
contact and seals the vacuum interrupter against the sur-
rounding atmosphere.
Switching Operation (Figures 5 and 6a)
When a closing command is initiated, the closing spring
(62), which was previously charged by hand or by the mo-
tor, actuates the moving contact through the jack shaft (63),
lever, contact pressure spring (49), insulating coupler (48),
and angled lever.
The forces that occur when the action of the insulating cou-
pler (48) is converted into the vertical action of the moving
contact are absorbed by the guide link, which pivots on the
pole bottom and the eye bolt.
During closing, the opening spring (64) (Figure 6a) and the
contact pressure springs (49) are charged and latched by
pawl (64.2) (Figure 6b). The closing spring (62) (Figure 6a) of
the motor-operated circuit breaker is recharged immediately
after closing.
In the closed state, the necessary contact pressure is main-
tained by the contact pressure spring (49) and the atmo-
spheric pressure. The contact pressure spring automatically
compensates for arc erosion, which is very small.
When a opening command is given, the energy stored in
the opening and contact pressure springs (49) is released
by pawl (64.2) (Figure 6b). The opening sequence is similar
to the closing sequence. The residual force of the opening
spring arrests the moving contact in the open position.
Operating Mechanism
The operating mecha-
nism is comprised of the mechanical and electrical compo-
nents required to:
1. Charge the closing spring with sufficient potential energy
to close the circuit breaker and to store opening energy
in the opening and contact pressure springs.
2. Mechanisms to release closing and opening actions.
3. Means of transmitting force and motion to each of three
pole positions.
4. Operate all these functions automatically through electri-
cal charging motor, cutout switches, antipump relay,
close coil, open coil, and auxiliary switch.
5. Provide indication of the circuit breaker status (open/
closed), spring condition (charged/discharged), and
number of operations.
8

Figure 6a. Stored Energy Operating Mechanism (Circuit Breaker Shown in Open Position)
50.2 Charging mechanism gear box
50.3 Charging flange
50.3.1 Driver
50.4 Spring charging motor 88
50.4.1 Limit switches
50.5 Manual spring charging port
53 Close pushbutton
53.1 Close coil 52SRC
54 Open pushbutton
54.1 Trip coil 52T
55 Closing spring charge indicator
55.1 Linkage
55.2 Control lever
58 Close-open indicator
59 Operation counter
60 Operator housing
61.8 Shock absorber
62 Closing spring
62.1 Charging shaft
62.2 Crank
62.3 Cam disc
62.5 Lever
62.5.1 Pawl roller
62.5.2 Close latch pawl
62.6 Drive lever
62.8 Trip free coupling rod
62.8.1 Spring return latch
62.8.3 Trip free coupling lever
63 Jack shaft
63.1 Lever - phase C
63.5 Lever - phase B
63.7 Lever - phase A
64 Opening spring
68 Auxiliary switch
68.1 Auxiliary switch link
60 61.8 64
63.5
62.8
63
68
53.1
68.1
54.1
54
55.2
50.5
50.2
50.3
50.3.1
62.6
62.3
62.5.2
62.5
53
62.5.1
55.1
62
62.2
50.4.1
55
62.8.1
59
58
9
62.1
63.7
63.1
50.4
62.8.3
Vacuum Interrupter/Operator Description

Figure 6b. Stored Energy Operating Mechanism (Circuit Breaker Shown in Closed Position)
62.8.1
62.8
62.8.2 64.3
64.3.1
54
64.2
Vacuum Interrupter/Operator Description
10
54 Open pushbutton
62.8 Trip free coupling rod
62.8.1 Spring return latch
62.8.2 Trip free coupling link (Draw bar)
64.2 Trip latch pawl
64.3 Lever
64.3.1 Pawl roller

Vacuum Interrupter/Operator Description
Construction
The essential parts of the operating mechanism are shown
in Figures 6a and 6b. The control and sequence of operation
of the mechanism is described in Figure 8.
Motor Operating Mechanism (Figure 6a)
The spring charging motor (50.4) is bolted to the charging
mechanism (50.2) gear box installed in the operator housing.
Neither the charging mechanism nor the motor require any
maintenance.
Mode of Operation
The operating mechanism is of the stored-energy trip free
type, i.e., the charging of the closing spring is not automati-
cally followed by the contacts changing position, and the
closing function may be overridden by an opening com-
mand at any time.
When the stored-energy mechanism has been charged, the
instant of operation can be chosen as desired.
The mechanical energy for carrying out an “open-close-
open” sequence for auto-reclosing duty is stored in the clos-
ing and opening springs.
Charging
The details of the closing spring charging mechanism are
shown in Figure 6a. The charging shaft is supported in the
charging mechanism (50.2), but is not coupled mechani-
cally with the charging mechanism. Fitted to it are the crank
(62.2) at one end, and the cam (62.3), together with lever
(62.5), at the other.
When the charging mechanism is actuated by hand with
a hand crank (Figures 9a and 9b) or by a motor (50.4), the
flange (50.3) turns until the driver (50.3.1) locates itself in
the cutaway part of the cam disc (62.3), thus causing the
charging shaft to follow. The crank (62.2) charges the closing
spring (62). When the closing spring has been fully charged,
the crank actuates the linkage (55.1) via the control lever
(55.2) for the “closing spring charged” indicator (55), and
actuates the limit switches (50.4.1) for interrupting the motor
supply. At the same time, the lever (62.5) at the other end
of the charging shaft is securely locked by the latching pawl
(62.5.2). When the closing spring is being charged, cam disc
(62.3) follows idly, i.e., it is brought into position for closing.
Closing (Figures 6a, 6b and 7a - 7d)
If the circuit breaker is to be closed locally, the closing spring
is released by pressing the CLOSE button (53). In the case
of remote control, the close coil 52SRC (53.1) unlatches the
closing spring (62).
As the closing spring discharges, the charging shaft (62.1) is
turned by crank (62.2). The cam disc (62.3) at the other end
of the charging shaft actuates the drive lever (62.6), with the
result that jack shaft (63) is turned by lever (63.5) via the trip
free coupling rod (62.8). At the same time, the levers (63.1),
(63.5) and (63.7) fixed on the jack shaft operate the three in-
sulating couplers (48) (Figure 5) for the circuit breaker poles.
Lever (63.7) changes the Open-close indicator (58) over to
Open. Lever (63.5) charges the opening spring (64) dur-
ing closing, and the circuit breaker is latched in the closed
position by lever (64.3) with pawl roller (64.3.1) and by pawl
(64.2). Lever (63.1) actuates the auxiliary switch (68) through
the linkage (68.1).
The crank (62.2) on the charging shaft (62.1) moves the link-
age (55.1) by acting on the control lever (55.2). The closing
spring charged indication is thus canceled, and the limit
switches (50.4) switch in the control supply to cause the
closing spring to recharge immediately.
Trip Free Operation (Figures 6a and 6b)
The trip free coupling rod (62.8) permits the immediate
decoupling of the drive lever (62.6) and the jack shaft (63) to
override closing action by trip command or by means of the
racking interlocks.
The trip free coupling rod (62.8) forms a link between the
drive lever (62.6) and the jack shaft (63). The rigidity of this
link depends upon a spring return latch (62.8.1) carried
within the coupling rod. The latch pivots within the coupling
rod and is normally positioned to ensure the rigidity of the
coupling rod. Trip free coupling link (62.8.2) and trip free
coupling lever (62.8.3) cause the spring return latch posi-
tion to be dependent upon the normal tripping components
and the racking interlock. Thus, whenever a trip command is
applied or the circuit breaker is not in the fully CONNECT or
TEST position, the trip free coupling rod is no longer rigid,
effectively decoupling the drive lever and jack shaft. Under
these conditions the vacuum interrupter contacts cannot be
closed.
Opening (Figure 6a)
If the circuit breaker is to be opened locally, the opening
spring (64) is released by pressing the Open pushbutton
(54). In the case of an electrical command being given, the
trip coil 52T (54.1) unlatches the opening spring (64).
The opening spring (64) turns the jack shaft (63) via lever
(63.5); the sequence being similar to that for closing.
11

Figure 7a. Operating Mechanism Section Diagram
62.8.2 Trip free draw bar
62.8.6 Interlock lever-push rod
62.8.7 Interlock lever-actuator
62.8.8 Trip free actuator
Vacuum Interrupter/Operator Description
12
Operating Mechanism Open, Closing Spring Discharged
* Items changed from 7c on ‘Trip’ Operation) (Underlined items
changed from 7b on ‘Closed Spring Discharge’ Operation)
Figure 7b. Operating Mechanism Section Diagram Operat-
ing Mechanism Open, Closing Spring Charged
* Items changed from 7d on ‘Trip’ Operation) (Underlined items
changed from 7a on ‘Closed Spring Charge’ Operation)
48 Insulating coupler
50.3 Charging flange
50.3.1 Driver
53 Close pushbutton
53.1 “Close coil, 52SRC”
54 Open pushbutton
54.1 “Trip coil, 52T”
62.1 Charging shaft
62.2 Crank
62.2.2 Closing spring mounting
62.8.1 Spring return latch
62.3 Cam disc
62.5 Lever
62.5.1 Pawl roller
62.5.2 Close latch pawl
62.6 Drive lever
62.8 Trip free coupling rod
62.8.2 Trip free coupling link (Draw bar)
62.8.3 Trip free coupling lever
62.8.5 Push rod & cam assembly
63. Jack shaft
63.1 Lever-phase C
63.5 Lever-phase B
63.7 Lever-phase A
64. Opening spring
64.2 Trip latch pawl
64.2.1 Trip latch pin
64.2.2 Latching pawl release lever
64.3 Lever
64.3.1 Jack shaft pawl
64.5 Opening spring shaft

62.8.5 Push rod & cam assembly
62.8.8Trip free actuator
63.5 Lever-phase B
64 Opening spring 64.5 Opening spring shaft
Vacuum Interrupter/Operator Description
13
Figure 7c. Operating Mechanism Section Diagram
Mechanism Closed, Closing Spring Discharged
(Callout items changed from 7b on ‘Circuit Breaker Close’ Opera-
tion)
Figure 7d. Operating Mechanism Section Diagram Op-
erating Mechanism Closed, Closing Spring Charged
(Callout items changed from 7c on ‘Closing Spring Charge’ Opera-
tion)
62.5.2 Close latch pawl
62.8.1 Spring return latch
62.8.2Trip free draw bar
62.8.3Trip free lever
62.8.6 Interlock lever-push rod
62.8.7 Interlock lever-actuator
64.2.1Trip latch pin
64.2.2 Latching pawl release lever
64.3 Lever
64.3.1 Jack shaft pawl

Figure 8. Operator Sequential Operation Diagram.
14
Rapid auto reclosing.
The closing spring is recharged automatically as described
above. Therefore, when the circuit breaker is closed both its
springs are charged. The closing spring charges the opening
spring during closing. As a result, the circuit breaker is
capable of an O-3s-CO-15s-CO operating cycle.
The dashed line shows the operating sequence
initiated by impairing the closing command.
Anti-pumping feature (Divice 52Y)
Care must be taken to see that a continuously ap-
plied closing command does not cause the circuit
breaker to reclose after it has tripped out on a fault
otherwise it may sustain damage by the “pumping”
effect.
Vacuum Interrupter/Operator Description

Figure 9a. Use of Manual Spring Charging Crank Figure 9b. Use of Manual Spring Charging Crank
50
50.5
50.6
The circuit breaker may be operated only with the original
hand crank (50), in order to avoid injures as a result of the mo-
tor suddenly starting up.
Vacuum Interrupter/Operator Description
Rapid Auto-Reclosing
Since the closing spring is automatically recharged by the
motor operating mechanism when the circuit breaker has
closed the operating mechanism is capable of an open-
close-open duty cycle as required for rapid auto-reclosing.
Manual Operation
Electrically operated vacuum circuit breakers can be oper-
ated manually if the control supply should fail.
Manually Charging the Closing Spring
(Figures 9a and 9b).
Insert the hand crank (50) with the over running coupling
pushed forward (50.6) through the opening (50.1) onto hand
crank coupling (50.5) and turn it clockwise (about 48 revolu-
tions) until the closing spring indicator (55) shows “Charged”.
The hand crank is coupled with the charging mechanism via
an over-running coupling; thus the operator is not exposed
to any risk should the control supply recover during charg-
ing.
Manual Closing (Figure 6a)
Press the close button (53). The close-open indicator (58)
will then display “Closed” and the closing spring condition
indicator (55) will now read “Discharged”.
Manual Opening (Figure 6a)
The opening spring (64) is charged during closing. To open
the circuit breaker, press the Open pushbutton (54) and
“OPEN” will be displayed by indicator (58).
15

Figure 10.Typical Elementary Diagram
Vacuum Interrupter/Operator Description
Elementary Diagram (Figure 10)
A typical elementary diagram is shown in Figure 10 for DC motor, close and trip operation.
16

1294-94
1 Magnet core
3 Housing
5 Mounting holes (3)
7 Magnet coil
9 Magnet armature
11Tension spring
13 Adjusting (Factory set)
screw for 11
15Tripping pin
21 Locking pin
23 Striker pin
25 Latch
27 Spring
31 Striker pin spring
33Terminal block
23 11 21 25 27 7 31
13
9
15
5
3
1
33
Construction and Mode of Operation of Secondary
Shunt Release and Undervoltage Release (Figures 11,
12 and 13)
The release consists of a spring-power storing mechanism,
a latching device, and an electromagnet. These elements are
accommodated side by side in a housing (3), with a detach-
able cover and three through holes (5) for fastening screws.
The supply leads for the trip coil are connected to a terminal
block (33).
The energy-storing mechanism consists of the striker pin
(23) and its operating spring (31), which is mostly located
inside the striker pin (23). When the spring is compressed,
the striker pin is held by a latch (25), whose sloping face is
forced against the appropriately shaped striker pin (23) by
spring (27). The other end of the latch (25) is supported by a
partly milled locking pin (21), pivoted in the cover sheets of
the magnet armature (9). The armature (9) is pivoted in front
of the poles of the U-shaped magnet core, (1) and is pulled
away from it by the tension spring (11).
If the magnet coil (7) of the secondary shunt release 3AX1101
is energized by a trip signal, or if the tripping pin (15) is me-
chanically actuated, magnet armature (9) is swung against
the pole faces. When this happens, the latch (25) loses its
support and releases the striker pin (23), which is forced out
by the spring (31).
Vacuum Interrupter/Operator Description
Figure 11. Construction of Secondary Shunt Release (shown
charged).
Close coil (52SRC)
The close coil (3AY1510) is a standard component of the
circuit breaker which is used to unlatch the stored energy of
the closing spring and thus close the circuit breaker elec-
trically. It is available for both AC and DC operation. After
completion of a closing operation, the close coil is de-en-
ergized internally. If operated with AC voltage, a rectifier is
installed in the circuit breaker.
Trip coil (52T)
The trip coil (3AY1510) is a standard component of the circuit
breaker.The electrically supplied tripping signal is passed on
to the trip latching mechanism by means of a direct action
solenoid armature and the circuit beaker is thus opened. It is
available for both AC and DC operation. After completion of
an opening operation, the trip coil is de-energized internally.
If operated with AC voltage, a rectifier is installed in the
circuit breaker.
Indirect Releases (Secondary Shunt Release (DualTrip)
(52T1) or Undervoltage (27))
The indirect release provides for the conversion of modest
control signals into powerful mechanical energy impulses.
It is primarily used to open medium voltage circuit breakers
while functioning as a secondary shunt release (dual trip) or
undervoltage device.
These releases are mechanical energy storage devices.
Their internal springs are charged as a consequence of
the circuit breaker mechanism operation. This energy is
released upon application or removal (as appropriate) of ap-
plicable control voltages. Refer to Figures 11, 12 and 13.
The Secondary shunt release and Undervoltage release
mounts to the immediate right of the trip coil (54.1).
Secondary Shunt Release (52T1) (Figure 11)
A secondary shunt release (extra trip coil) is used for electri-
cal opening of the circuit breaker by protective relays or
manual control devices when more than one trip coil is
required. The second trip coil is generally connected to a
separate auxiliary supply (DC or AC) from the control supply
used for the normal trip coil. Undervoltage Release (27)
(Figures 12 and 13).
Undervoltage Release (27) (Figures 10 and 11)
The undervoltage release (3AX1103) is used for continuous
monitoring of the tripping supply voltage. If this supply volt-
age falls excessively, the undervoltage release will provide
for automatic tripping of the circuit breaker.
The undervoltage device may be used for manual or relay
tripping by employing a contact in series with undervoltage
device holding coil. Relay tripping may also be achieved by
employing a normally open contact in parallel with the hold-
ing coil. If this scheme is used, a resistor must be provided
to limit current when the normally open contact is closed.
Secondary shunt and undervoltage releases are available for
all standard ANSI control voltages.
17

Figure 12. Latch Details (shown charged).
Figure 13 Undervoltage Locked/Unlocked Selection.
Figure 14. CapacitorTrip Device
Vacuum Interrupter/Operator Description
18
On the undervoltage release 3AX1103, the latch (25) is held
by the locking pin (21) as long as the armature (9) is ener-
gized. If the circuit of the magnet coil (7) is interrupted, the
armature (9) drops off, thus causing the latch (25) to lose its
support and release the striker pin (23).
Following every tripping operation, the striker pin (23) must
be reset to its normal position by loading the spring (31).This
takes place automatically via the operating mechanism of
the circuit breaker.
Since the striker pin of the undervoltage release 3AX1103 is
latched only when the armature is energized, the undervolt-
age release is provided with a screw (29), for locking the
striker pin (23) in the normal position for adjusting purposes
or for carrying out trial operations during circuit breaker ser-
vicing. Position A (locked) disables the undervoltage release.
Position B (unlocked) is the normal operating position.
CapacitorTrip Device
The capacitor trip device is an auxiliary tripping option
(capacitor trip is a system that should be mounted on the
drawout truck) providing a short term means of storing ad-
equate electrical energy to ensure circuit breaker tripping.
This device is applied in circuit breaker installations lack-
ing independent auxiliary control power or station battery.
In such installations, control power is usually derived from
the primary source. In the event of a primary source fault
or disturbance the capacitor trip device will provide short
term tripping energy for circuit breaker opening due to relay
operation.
The capacitor trip converts 120 or 240 VAC control voltage
to a DC full wave voltage which is used to charge a large
capacitor to the peak of the converted wave.
(Figure 14).
Shock Absorber
Circuit breakers are equipped with a hydraulic shock ab-
sorber (61.8) (Figure 6a). The purpose of this shock
absorber is to limit overtravel and rebound of the vacuum
interrupter movable contacts during the conclusion of an
opening operation. The shock absorber action affects only
the end of an opening operation.
Auxiliary Switch (52a/b)
Figure 6a shows the circuit breaker mounted auxiliary
switch (68). This switch provides auxiliary contacts for
control of circuit breaker closing and opening functions.
Contacts are available for use in relaying and external logic
circuits. This switch is driven by linkage (68.1) connected
to the jack shaft (63). The auxiliary switch contains both ‘b’
(Normally Closed) and ‘a’ (Normally Open) contacts. When
the circuit breaker is open, the ‘b’ contacts are closed and
the ‘a’ contacts are open.
Spring Charging Motor (88)
Spring charging motors (50.4) (Figure 6a) are available for
both AC and DC operation. If operated with AC voltage, a
rectifier is installed in the circuit breaker.