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MDN-508

Eaton MDS-408, MDN-508, MDS-508, MDS-808, MDS-608 Instructions For Installation, Operation And Maintenance

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Double-wide Fixed
Standard Frame Fixed
Narrow Frame Fixed
Instructions for Installation, Operation and Maintenance of Magnum DS, DSX and DSL Low Voltage Power Circuit Breakers
I.B. 2C12060H08 Supersedes I.B. 2C12060H07 dated April 2005
Effective May 2006
IB2C12060H08
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Instruction Book
Page iii
Effective: May 2006
I.B. 2C12060H08
For application information, consult Cutler-Hammer or see applicable Product Guides, Technical Documents, Application Publications and/or Industry Standards.
SAFETY
All safety codes, safety standards and/or regulations must be strictly observed in the installation, operation and maintenance of this equipment.
THE WARNINGS AND CAUTIONS INCLUDED AS PART OF THE PROCEDURAL STEPS IN THIS MAN­UAL ARE FOR PERSONNEL SAFETY AND PROTEC­TION OF EQUIPMENT FROM DAMAGE. AN EXAM­PLE OF A TYPICAL WARNING LABEL HEADING IS SHOWN ABOVE TO FAMILIARIZE PERSONNEL WITH THE STYLE OF PRESENTATION. THIS WILL HELP TO INSURE THAT PERSONNEL ARE ALERT TO WARNINGS. IN ADDITION, CAUTIONS ARE ALL UPPER CASE AND BOLDFACE.
PURPOSE
This instruction manual is expressly intended to cover the installation, operation and maintenance of Magnum DS (MDS), DSX (MDSX) and Magnum DSL (MDSL) Power Circuit Breakers. These circuit breakers may be supplied as part of complete switchboard assemblies or as separate components. This manual applies only to the circuit breaker and (if drawout) it’s mating cassette. The Magnum DSL circuit breaker can only be supplied as a drawout device. In the case of fixed versions of Magnum DS circuit breakers, certain sections of this manual, referring to such items as position interlocks and the drawout mechanism, will not apply.
Trip units associated with Magnum DS, DSX and DSL Power Circuit Breakers will be addressed in a general manner in this manual. Specific trip unit details and time-current characteristic curves are covered in sepa­rate documents specific to the trip units.
Magnum DS, DSX and DSL circuit breaker accessory items are discussed briefly in this manual. Field installa­tion instructions for such items, however, are covered in individual instruction leaflets specific to the accessory. This information is also available from the Cutler­Hammer website at www.EatonElectrical.com
All possible contingencies which may arise during installation operation or maintenance, and all details and variations of this equipment do not purport to be covered by these instructions. If further information is desired by purchaser regarding his particular installation, operation or maintenance of particular equipment, contact the local Cutler­Hammer Inc. representative.
!
WARNING
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Instruction Book
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Effective: May 2006
I.B. 2C12060H08
TABLE OF CONTENTS
SECTION 1: INTRODUCTION PAGE
1-1 General Information.............................................................................................................................................1
1-2 Safety Features ...................................................................................................................................................2
1-3 Safety Practices ..................................................................................................................................................2
1-4 Qualified Personnel .............................................................................................................................................3
1-5 Other Publications and Documentation...............................................................................................................3
SECTION 2: RECEIVING, HANDLING AND INSTALLATION
2-1 General Information.............................................................................................................................................4
2-2 Suggested Tools .................................................................................................................................................4
2-3 Unpacking Circuit Breaker...................................................................................................................................4
2-3.1 Storing Circuit Breaker ...........................................................................................................................4
2-4 Lifting Circuit Breaker ..........................................................................................................................................5
2-5 Circuit Breaker Inspection ...................................................................................................................................6
2-6 Installing Drawout Circuit Breaker .......................................................................................................................6
2-6.1 Rejection Interlocks ................................................................................................................................6
2-6.2 Circuit Breaker Positioning .....................................................................................................................7
2-6.3 Levering Circuit Breaker .........................................................................................................................9
2-7 Fixed Circuit Breaker.........................................................................................................................................10
2-8 Circuit Breaker Operation..................................................................................................................................10
SECTION 3: CIRCUIT BREAKER DESCRIPTION AND OPERATION
3-1 Introduction........................................................................................................................................................11
3-1.1 MDSL Application/Operation ................................................................................................................15
3-2 Basic Circuit Breaker Assembly ........................................................................................................................15
3-3 Pole Units ..........................................................................................................................................................15
3-3.1 Primary Moving Contacts .....................................................................................................................16
3-3.2 Primary Stationary Contacts.................................................................................................................16
3-4 Operating Mechanism .......................................................................................................................................17
3-4.1 Manual Operation .................................................................................................................................17
3-4.2 Electrical Operation ..............................................................................................................................18
3-4.3 Anti-Pump Feature ...............................................................................................................................18
3-5 Arc Chambers ...................................................................................................................................................18
3-5.1 Arc Chute .............................................................................................................................................18
3-6 Electronic Tripping System................................................................................................................................19
3-6.1 Microprocessor-based Trip Unit ...........................................................................................................19
3-6.2 Rating Plug ...........................................................................................................................................21
3-6.3 Current Sensors ...................................................................................................................................21
3-6.4 Trip Actuator .........................................................................................................................................22
3-6.5 Mechanical Trip Flag ............................................................................................................................22
3-6.6 Making Current Release.......................................................................................................................22
3-6.7 High Instantaneous Trip Option (Magnum DS Only) ............................................................................22
3-6.8 Voltage Taps ........................................................................................................................................23
3-7 Secondary Contacts and Connection Diagrams ...............................................................................................23
3-7.1 Connection Diagrams ...........................................................................................................................24
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I.B. 2C12060H08
PAGE
3-8 Accessory Devices ............................................................................................................................................46
3-8.1 Plug-In Electrical Accessories ..............................................................................................................46
3-8.2 Internal Electrical Accessories .............................................................................................................48
3-8.3 Mechanical Accessories .......................................................................................................................50
3-9 MDSL Limiters/Blown Limiter Indication............................................................................................................53
3-9.1 MDSL Current Limiters .........................................................................................................................53
3-9.2 Blown Limiter Sensing ..........................................................................................................................53
SECTION 4: DRAWOUT CIRCUIT BREAKER AND CASSETTE
4-1 General .............................................................................................................................................................55
4-1.1 Drawout Cassette .................................................................................................................................55
4-2 Drawout Circuit Breaker Dimensions ................................................................................................................57
4-3 Drawout Cassette Dimensions ..........................................................................................................................57
SECTION 5: FIXED CIRCUIT BREAKER
5-1 General .............................................................................................................................................................59
5-2 Fixed Circuit Breaker Dimensions .....................................................................................................................59
SECTION 6: INSPECTION AND MAINTENANCE
6-1 General .............................................................................................................................................................60
6-2 General Cleaning Recommendations ...............................................................................................................60
6-3 When to Inspect ................................................................................................................................................60
6-4 What to Inspect .................................................................................................................................................61
6-4.1 Functional Field Testing .......................................................................................................................61
6-4.2 Arc Chute Inspection ............................................................................................................................62
6-4.3 Primary Contact Inspection ..................................................................................................................63
6-5 Circuit Breaker Modifications and Changes ......................................................................................................64
6-5.1 Rating Plug Replacement.....................................................................................................................64
6-5.2 Current Sensor Replacement ...............................................................................................................65
6-5.3 Current Limiter Replacement (MDSL) ..................................................................................................66
6-5.3.1 Replacing Type MA and MB Current Limiters ......................................................................................55
6-5.3.2 Replacing Type MD Current Limiters ...................................................................................................66
6-5.3.3 Replacing Type MD Current Limiters on MDSL20 Breakers................................................................66
SECTION 7: TROUBLESHOOTING
7-1 Introduction........................................................................................................................................................67
SECTION 8: RENEWAL PARTS
8-1 General .............................................................................................................................................................70
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Instruction Book
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Effective: May 2006
I.B. 2C12060H08
FIGURES
Figure Title Page
1-1 Magnum DS Family of Low Voltage Power Fixed and Drawout Circuit Breakers (800-5000 Amperes) ..1
1-2 Typical Magnum Nameplate ....................................................................................................................2
1-3 & 1-4 Sample Designation Examples ................................................................................................................3
1-5 Typical Magnum DSL (MDSL) Drawout Breaker with Integral Current Limiters ......................................3
2-1 Shipping Clamps for Drawout Circuit Breaker ..........................................................................................4
2-2 Magnum DS Circuit Breaker with Lifting Yoke Attached ..........................................................................5
2-3 Rear View Showing Current Sensor Rating Through Viewing Window ....................................................6
2-4 One Side of Drawout MDS Circuit Breaker Properly Seated on Extension Rail ......................................6
2-5 Cassette Rejection Interlock Pin Positioning/Installation ..........................................................................7
2-6 Remove Position ......................................................................................................................................8
2-7 Disconnect Position ..................................................................................................................................8
2-8 Test Position ............................................................................................................................................8
2-9 Connect Position ......................................................................................................................................9
2-10 Cassette Label Showing Disconnected, Test and Connected Position of Recessed Cover ....................9
2-11 Levering Position Indication ....................................................................................................................10
2-12 Typical Fixed Magnum DS Circuit Breaker ............................................................................................10
3-1 Typical MDS Drawout Circuit Breaker Features (Front and Rear Views) ..............................................11
3-2 Typical MDS Fixed Circuit Breaker Features (Front and Rear Views)....................................................12
3-3 Typical MDSL Drawout Circuit Breaker Features (Front and Rear Views) ............................................12
3-4 Typical Double-wide MDS Standard Frame Circuit Breaker Features (Front and Rear Views)..............13
3-5 Typical Magnum DS Drawout Circuit Breaker Front Cover ....................................................................14
3-6 Typical Magnum Construction (Right Side View)....................................................................................15
3-7 Features of Magnum Moving Conductor Assembly ................................................................................15
3-8 Narrow Frame (8-finger) Moving Conductor Assembly ..........................................................................16
3-9 Standard Frame (12-finger) Moving Conductor Assembly......................................................................16
3-10 Parital Cross-Sectional View (Shown in Closed Position) ......................................................................16
3-11 Electrically Operated Drawout MDS Circuit Breaker with Front Cover Removed ..................................17
3-12 Circuit Breaker Closing Springs Being Manually Charged......................................................................18
3-13 Electrical Motor Operator to Charge Closing Spring ..............................................................................18
3-14 Cross Section of Conductor and Arc Control System ............................................................................19
3-15 Integral Arc Runner as Viewed From Top of Arc Chamber
(Arc Chute Removed and Circuit Breaker Closed) ................................................................................19
3-16 Magnum Arc Plate Assembly ..................................................................................................................19
3-17 Pictorial Diagram of Typical Current Sensing, Processing and Tripping System....................................20
3-18 Digitrip RMS 1150 Programmable Trip Unit Installed in Magnum DS Circuit Breaker............................21
3-19 Hand Held Tester ....................................................................................................................................21
3-20 Replaceable Current Sensors Shown with Bottom Adapters and Cover Plate Removed ......................22
3-21 Line Side Voltage Tap for 1150 Trip Unit ................................................................................................23
3-22 Top View Secondary Connectors............................................................................................................23
3-23 Secondary Connector Protective Hood ..................................................................................................23
3-24 Cassette Mounted Secondary Wiring ......................................................................................................24
3-25 AMP Secondary Wiring Removal Tool.....................................................................................................24
3-26 Digitrip Connection Diagrams .................................................................................................................25
thru
3-46 Digitrip Connection Diagrams .................................................................................................................45
3-34 Through-the-Window Electrical Accessories ...........................................................................................46
3-35 Shunt Trip with Cutoff Switch...................................................................................................................46
3-36 Shunt Trip Switch Installed ......................................................................................................................46
3-37 Spring Release with Optional Latch Check Switch ..................................................................................47
3-38 Undervoltage Release Device .................................................................................................................47
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Instruction Book
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I.B. 2C12060H08
Figure Title Page
3-39 Shunt Trip, Spring Release and Undervoltage Release Installed............................................................47
3-40 Auxiliary Switch (2A/2B)...........................................................................................................................48
3-41 Mechanical Trip Indicator with Associated Overcurrent Trip Switch ........................................................48
3-42 Motor Operator Kit ...................................................................................................................................49
3-43 Motor Operator Installed in Narrow Frame Circuit Breaker......................................................................49
3-44 Cover Mounted Key Lock and Operations Counter................................................................................. 50
3-45 Cassette Mounted Key Lock ....................................................................................................................50
3-46 ON-OFF Pushbutton Lockable Cover Plate.............................................................................................50
3-47 Safety Shutters in Closed Position...........................................................................................................51
3-48 Safety Shutters in Open Position .............................................................................................................51
3-49 Cell Switch (Drawout Position Indicator) Unmounted ..............................................................................51
3-50 Cell Switches Mounted on Cassette ........................................................................................................51
3-51 Door Escutcheon and Gasket ..................................................................................................................51
3-52 IP54 Waterproof Cover ............................................................................................................................52
3-53 Cassette-Mounted 2-Way Cable Interlock ...............................................................................................52
3-54 Magnum DSL Circuit Breaker (Side View)...............................................................................................53
3-55 Blow Fuse Indicator .................................................................................................................................53
4-1 Drawout Circuit Breaker in Cassette .......................................................................................................55
4-2 Drawout Circuit Breaker with Automatic Primary Disconnects ................................................................55
4-3 Drawout Cassette Features .....................................................................................................................56
4-4 Narrow Frame Cassette (Horizontal Terminals) ......................................................................................57
4-5 Standard Cassette (Vertical Terminals) ..................................................................................................57
4-6 Basic Cassette (Without Stabs) ...............................................................................................................57
4-7 Universal Cassette, 4-Pole (Flat Terminal Pads).....................................................................................57
4-8 Typical MDSL Standard Cassette (Front View) .......................................................................................58
4-9 Typical MDSL Standard Cassette (Rear View)........................................................................................58
5-1 Fixed Circuit Breaker with Available Vertical Adaptor..............................................................................59
6-1 Top Rear View of Circuit Breaker with One Arc Chute Removed............................................................62
6-2 Bottom View of Arc Chute........................................................................................................................62
6-3 Primary Contacts with Circuit Breaker Open (Not Used for Contact Wear Inspection) ...........................63
6-4 Contact Inspection Area with Circuit Breaker Open.................................................................................63
6-5 Use of Contact Wear Indicator with Circuit Breaker Closed ....................................................................64
6-6 Trip Unit Rating Plug Location .................................................................................................................64
6-7 Current Sensor Cover in Place Over Sensors .........................................................................................65
6-8 One Current Sensor Shown Removed and Disconnected.......................................................................65
6-9 MD Limiters Shown Mounted in Extension ..............................................................................................66
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Instruction Book
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Effective: May 2006
I.B. 2C12060H08
TABLES
Table Title Page
1.1 Magnum DS Ratings at 240, 480, 600 volts ..............................................................................................2
1.2 Magnum DSL Ratings at 600 volts ............................................................................................................3
2.1 Circuit Breaker Weights .............................................................................................................................5
2.2 Rejection Interlock Pin Locations ...............................................................................................................7
3.1 Magnum Digitrip Trip Units ......................................................................................................................20
3.2 Magnum DS Current Sensors and Matching Rating Plugs ......................................................................22
3.3 Shunt Trip Ratings ...................................................................................................................................46
3.4 Spring Release Ratings ...........................................................................................................................47
3.5 Undervoltage Release .............................................................................................................................48
3.6 Auxiliary Switch, Overcurrent Trip Switch and Cell Switch Contact Ratings............................................48
3.7 Motor Operator.........................................................................................................................................49
3.8 MDSL Integral Current Limiter Selection .................................................................................................54
6.1 Inspection Frequency...............................................................................................................................60
7.1 Circuit Breaker Troubleshooting Guide ....................................................................................................67
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SECTION 1: INTRODUCTION
1-1 GENERAL INFORMATION
The Magnum DS and DSX Power Circuit Breakers can be fixed or drawout air circuit breakers utilizing an elec­tronic tripping system. The Magnum DSL circuit breaker utilizes the same tripping system, but is available only in the drawout configuration. MDSL and MDSX versions have current-limiting characteristics as indicated by the “Current Limiting” badge on the front covers. All break­ers are designed for use in both switchboard and metal­enclosed switchgear assemblies having maximum volt­ages of 635 volts ac MDS type breakers, 600 volts ac for MDSL type breakers, and 480 volts ac for MDSX type breakers. Magnum DS circuit breakers are available in three physical frame sizes with continuous current rat­ings from 800 through 6000A. and interrupting capacities from 42 kA to 200 kA. The three MDS physical frame sizes have common height and depth dimensions, differ­ing only in width (Figure 1-1). Magnum DSL circuit break- ers are available in one frame size with continuous cur­rent ratings from 800 through 2000A and an interrupting capacity up to 200,000A (Figure 1-5). Circuit breaker nameplates provide complete rating information. All Magnum DS, Magnum DSX, and Magnum DSL circuit breakers are 100 percent rated, UL listed, and are built and tested in an ISO 9002 certified facility to applicable NEMA, ANSI, IEEE and UL standards (Tables 1.1 and
1.2, Figures 1-2, 1-3 and 1-4).
Magnum circuit breakers use a rigid frame housing of engineered thermoset composite resins which has high strength structural properties, excellent dielectric char-
acteristics and arc tracking resistance.
MDS, MDSX and MDSL drawout circuit breakers are a through-the-door design having three breaker positions with the compartment door closed (CONNECT, TEST, DISCONNECT) and one position out of its compartment on extension rails (REMOVE). The operating mecha­nism is a two-step stored energy mechanism, either manually or electrically operated.
When withdrawn on captive compartment cassette extension rails, MDS, MDSX and MDSL circuit breakers can be inspected, accessory items added, and minor maintenance performed. The inside of the compartment can also be inspected with the circuit breaker on its extension rails.
Please read and understand these instructions before attempting to unpack, install, operate or maintain this equipment. Study the breaker and its mechanism carefully before attempting to operate it on an energized circuit.
MAGNUM CIRCUIT BREAKERS SHOULD NOT UNDER ANY CIRCUMSTANCES BE APPLIED OUT­SIDE THEIR NAMEPLATE RATINGS. OPERATION OUTSIDE OF THESE RATINGS COULD RESULT IN DEATH, BODILY INJURY OR PROPERTY DAMAGE.
Instruction Book
Page 1
Effective: May 2006
I.B. 2C12060H08
Figure 1-1 Family of Magnum DS (MDS) Low Voltage Power Fixed and Drawout Circuit Breakers (800-5000 Amperes)
NOTICE
Double-wide Fixed MDS
Narrow Frame Fixed MDS
Standard Frame Drawout MDS
!
WARNING
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Instruction Book
Page 2
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I.B. 2C12060H08
1-2 SAFETY FEATURES
Magnum DS, DSX and DSL circuit breakers and associ­ated drawout equipment are manufactured with built-in interlocks and safety related features. They are provided to reduce hazards to operating personnel and provide proper operating sequences.
MAGNUM DS, DSX AND DSL CIRCUIT BREAKERS ARE ROBUST AND ARE PROVIDED WITH SAFETY FEATURES. NEVERTHELESS, THE VOLTAGES, CURRENTS AND POWER LEVELS AVAILABLE IN AND AROUND THIS EQUIPMENT WHEN IT IS IN OPERATION ARE EXTREMELY DANGEROUS AND COULD BE FATAL. UNDER NO CIRCUMSTANCES SHOULD INTERLOCKS AND OTHER SAFETY FEA­TURES BE MADE INOPERATIVE, AS THIS MAY RESULT IN DEATH, BODILY INJURY OR PROPERTY DAMAGE.
1-3 SAFETY PRACTICES
To protect personnel associated with the installation, operation and maintenance of this equipment, the fol­lowing practices must be followed:
Table 1.1 Magnum DS/DSX Ratings at 240, 480, 600 volts
!
WARNING
A
B
C
D
E
A
Figure 1-2 Typical Magnum DS (MDS) Nameplate
Low voltage power circuit breaker family name
Breaker family designation number
C
Breaker frame size in amperes
D
Interrupting capacity rating
E
Factory Equipped Accessories
Maximum Breaker Interrupting Short Time Amperes Designation Rating Rating
800 MDN-408 42 kA 42 kA
MDN-508 50 kA 50 kA MDN-608 65 kA 65 kA MDS-X08 200 kA (240v, 480v.) 30 kA MDS-408 42 kA 42 kA
MDS-508 50 kA 50 kA MDS-608 65 kA 65 kA MDS-808 85 kA 85 kA MDS-C08 100 kA 85 kA
1200 MDN-412 42 kA 42 kA
MDN-512 50 kA 50 kA MDN-612 65 kA 65 kA MDS-X12 200 kA (240v, 480v.) 30 kA MDS-412 42 kA 42 kA
MDS-512 50 kA 50 kA MDS-612 65 kA 65 kA MDS-812 85 kA 85 kA MDS-C12 100 kA 85 kA
1600 MDN-416 42 kA 42 kA
MDN-516 50 kA 50 kA MDN-616 65 kA 65 kA MDS-X16 200 kA (240v, 480v.) 30 kA MDS-416 42 kA 42 kA
MDS-516 50 kA 50 kA MDS-616 65 kA 65 kA MDS-816 85 kA 85 kA MDS-C16 100 kA 85 kA
2000 MDS-520 50 kA 50 kA
MDS-X20 200 kA (240v, 480v.) 30 kA MDS-620 65 kA 65 kA MDS-820 85 kA 85 kA MDS-C20 100 kA 85 kA
2500 MDS-525 50 kA 50 kA
MDS-X25 200 kA (240v, 480v.) 50 kA MDS-625 65 kA 65 kA MDS-825 85 kA 85 kA MDS-C25 100 kA 85 kA
3000 MDS-630 65 kA 65 kA
MDS-830 85 kA 85 kA MDS-C30 100 kA 85 kA
3200 MDS-X32, 3N 200 kA (240v, 480v.) 50 kA
MDS-632 65 kA 65 kA MDS-832 85 kA 85 kA MDS-C32 100 kA 85 kA
4000 MDS-X40 200 kA (240v, 480v.) 50 kA
MDS-840, 84N 85 kA 85 kA MDS-C40, C4N 100 kA 100 kA
5000 MDS-X50 200 kA (240v, 480v.) 50 kA
MDS-850, 85N 85 kA 85 kA MDS-C50, C5N 100 kA 100 kA
6000 MDS-860, 86N 85 kA 85 kA
MDS-C60, C6N 100 kA 100 kA
B
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M D S C 3 2
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I.B. 2C12060H08
1. Only qualified electrical personnel familiar with the equipment, its operation and the associated hazards should be permitted to work on the equipment. Additionally, only qualified personnel should be per­mitted to install or operate the equipment.
2. Always be certain that the primary and secondary cir­cuits are de-energized or the circuit breaker is removed to a safe work location before attempting any maintenance.
3. For maximum safety, only insert a completely assem­bled breaker into an energized cell.
4. Always ensure that drawout circuit breakers are in one of their designed cell positions, such as Connect, Test, Disconnect or Remove. A circuit breaker per­mitted to remain in an intermediate position could result in control circuits being improperly connected resulting in electrical failures.
1-4 QUALIFIED PERSONNEL
For the purpose of operating and maintaining low volt­age power circuit breakers, a person should not be con­sidered qualified if the individual is not thoroughly trained in the operation of the circuit breaker and how it interfaces with the assembly in which it is used. In addi­tion, the individual should have knowledge of the con­nected loads.
For the purpose of installing and inspecting circuit breakers and their associated assembly, a qualified per­son should also be trained with respect to the hazards inherent to working with electricity and the proper way to perform such work. The individual should be able to de­energize, clear and tag circuits in accordance with established safety practices.
1-5 OTHER PUBLICATIONS AND DOCUMENTATION
In addition to this instruction manual, other printed infor­mation and documentation is available and supplied as appropriate. This additional information can include, but not necessarily be limited to, an instruction manual for a specific electronic trip unit, instruction leaflets for acces­sory items, renewal parts information, necessary dimen­sional drawings and a Product (application) Guide. Specific reference documents associated with Magnum DS, DSX and DSL circuit breakers are listed in a sepa-
rate document entitled Engineering Data TD01301004E
Figure 1-3 Typical Magnum DS Designation Example
Circuit Breaker
Type
MDS - Standard and
Double Wide Frames MDN - Narrow Frame
Interrupting
Capacity
4 - 42,000 5 - 50,000 6 - 65,000 8 - 85,000 C - 100,000 E - 150,000 X - 200,000
Frame
Size
08 - 800 Amps 12 - 1200 Amps 16 - 1600 Amps 20 - 2000 Amps 25 - 2500 Amps 30 - 3000 Amps 32 - 3200 Amps 40 - 4000 Amps 50 - 5000 Amps
M D S L 0 8
Figure 1-4 Typical Magnum DSL Designation Example
Circuit Breaker
Type
MDSL- Standard Frame with Integral Current Limiters
Interrupting
Capacity
L - 200,000
Frame
Size
08 - 800 Amps 12 - 1200 Amps 16 - 1600 Amps 20 - 2000 Amps
Table 1.2 Magnum DSL Ratings at 600 Volts and Below
Breaker Designation
Frame Size Amperes
Max. Interrupting Rating, RMS Sym. Amp., System Voltage 600 or Below
MDSL08 MDSL12 MDSL16 MDSL20
800 1200 1600 2000
200,000 200,000 200,000 200,000
Figure 1-5 Typical Magnum DSL(MDSL) Drawout Circuit Breaker with Integral Current Limiters
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I.B. 2C12060H08
Instruction Book
Page 4
Effective: May 2006
Figure 2-1 Shipping Clamps for Drawout Circuit Breaker
SECTION 2: RECEIVING, HANDLING AND INSTALLATION
2-1 GENERAL INFORMATION
Magnum DS, DSX and DSL Power Circuit Breakers, when supplied as part of an assembly, may be shipped already installed in their respective breaker compart­ments. Receiving and handling of this equipment is addressed in an assembly instruction manual supplied with the assembled equipment. This instruction manual applies to only the circuit breakers.
2-2 SUGGESTED TOOLS
A large number of different tools are not required to properly install and maintain Magnum DS, DSX and DSL circuit breakers. The following tools are, however, suggested:
• Flat blade screwdriver
• Phillips head screwdriver
• 3/8” socket (rachet) wrench
• 10 mm socket
• 17 mm socket
• Secondary wiring removal tool
2-3 UNPACKING CIRCUIT BREAKER
Before beginning to unpack new Magnum circuit break­ers, read and understand these directions. Following the directions will ensure that no damage is caused.
Shipping containers should be inspected for obvious signs of rough handling and/or external damage incurred during the transportation phase. Record any observed damage for reporting to the transportation car­rier and Cutler-Hammer, once the inspection is complet­ed. All reports and claims should be as specific as pos­sible and include the order number and other applicable nameplate information.
Every effort is made to ensure that Magnum circuit breakers arrive at their destination undamaged and ready for installation. Care should be exercised, howev­er, to protect the breakers from impact at all times. Do not remove protective packaging until the breakers are ready for inspection, testing and/or installation.
When ready to inspect and install a Magnum circuit breaker, carefully remove the banding straps and lift off the cardboard box. Remove any additional packing material and internally packed documentation. The cir­cuit breaker and/or cassette are mounted to a wooden shipping pallet.
On drawout circuit breakers shipped without a cassette, two shipping clamps hook into the breaker side plates and are held to the pallet with 4 lag screws (Figure 2-1). Remove the lag screws and clamps. Save the screws and clamps for future shipment of the breaker. On empty cassettes, remove the 4 or 5 lag screws and/or machine screws which pass through the floorpan of the cassette holding it to the wooden pallet. On drawout breakers shipped in a cassette, first remove the breaker from the cassette using the levering mechanism and drawout rails. After the breaker is removed the machine screws passing through the floorpan can be removed.
Shipping Clamp
On fixed breakers, remove the lag screws passing through the mounting feet which hold the breaker to the pallet.
Circuit breakers are designed to be easily lifted from the wooden pallet using an appropriate lifting yoke and overhead or portable lifting device (Figure 2-2).
2-3.1 STORING CIRCUIT BREAKER
If it is necessary to store a circuit breaker before instal­lation, do so in its original shipping container. Keep the circuit breaker in a clean dry place. Ensure there is ample air circulation and heat, if necessary, to prevent condensation. It is very important that the circuit break­er not be exposed to dirt or moisture.
A circuit breaker that has been stored for any length of time should be operated a minimum of five times before it is placed in service.
NOTICE
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I.B. 2C12060H08
Instruction Book
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Effective: May 2006
Breaker Weights (lbs) Model Fixed Drawout Universal Cassette
3P 4P 3P 4P 3P 4P
MDN-408 95 120 107 136 61 70 MDN-508 MDN-608 MDN-412 MDN-512 MDN-612 MDN-416 MDN-516 MDN-616
MDS-408 114 141 130 161 117 123
MDS-508 118 146 138 172 117 123 MDS-608 MDS-412 MDS-512 MDS-612 MDS-416 MDS-516 MDS-616
MDS-520 128 160 155 194 117 123 MDS-620 MDS-808 MDS-812 MDS-816 MDS-820 MDS-C08 MDS-C12 MDS-C16 MDS-C20
MDS-525 150 190 189 240 123 150 MDS-625 MDS-630 MDS-632 MDS-825 MDS-830 MDS-832 MDS-C25 MDS-C30 MDS-C32
MDS-840, 84N 237 319 303 366 199 250 MDS-C40, C4N MDS-E40, E4N
MDS-850, 85N 276 360 343 441 212 266 MDS-860, 86N
MDS-C50, C5N MDS-C60, C6N MDS-E50, E5N MDS-E60, E6N
MDSL08 NA NA 180 NA 124 NA MDSL12 200 124 MDSL16 200 124 MDSL20 215 131
MDS-X08 169 NA 210 NA 140 NA MDS-X12 MDS-X16 MDS-X20 MDS-X25 MDS-X32 MDS-X40 279 NA 345 NA 210 NA MDS-X50
Table 2.1 Basic Circuit Breaker Weights
2-4 LIFTING CIRCUIT BREAKER
DO NOT ATTEMPT TO LIFT CIRCUIT BREAKERS WITH ORDINARY CRANE HOOKS, ROPES, CHAINS OR OTHER SUCH DEVICES. FAILURE TO FOLLOW THIS CAUTION COULD RESULT IN DAMAGE TO VITAL PARTS SUCH AS ARC CHUTES, BARRIERS AND WIRING OR THE ENTIRE CIRCUIT BREAKER.
To closely examine, install or just become more familiar with the circuit breaker, carefully lift and place the circuit breaker on a solid work surface capable of handling the circuit breaker’s weight (Table 2.1) or on the captive drawout extension rails of the breaker compartment (Figure 2-2). This is accomplished by using the appro­priate lifting yoke and lifter. The lifting yoke consists of two steel hooks specially shaped to hook under the inte­gral molded lifting handles on both sides of the circuit breaker (Figure 3-1). Every effort should be made dur­ing lifting to minimize circuit breaker swing and tilt.
If the circuit breaker is to be lifted onto compartment extension rails, follow the instructions in paragraph 2-6 entitled “Installing Drawout Circuit Breaker.”
!
CAUTION
Figure 2-2 Magnum DS Circuit Breaker with Lifting Yoke Attached
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2-5 CIRCUIT BREAKER INSPECTION
All circuit breakers, once removed from their shipping containers, should be visually inspected for any obvious damage.
The current rating of the rating plug installed in the trip unit should match the current rating of the sensors mounted on the lower primary stabs of the circuit break er. Check to make sure that this match exists. The rat­ing plug rating can be viewed from the front of the circuit breaker (Figure 3-4). The sensor rating can be viewed through the viewing windows at the rear of the circuit breaker (Figure 2-3). Sensors and rating plugs can be easily changed as described in Section 6.
2-6 INSTALLING DRAWOUT CIRCUIT BREAKER
In structures equipped for drawout circuit breakers, a bolted-in cassette with movable extension rails supports the circuit breaker (Figures 2-2 and 2-4). The extension rails must first be pulled all the way out. Once the rails are fully extended, the circuit breaker can be carefully placed on the extension rails.
IT IS IMPORTANT TO TAKE GREAT CARE WHEN PLACING A DRAWOUT CIRCUIT BREAKER ON ITS EXTENSION RAILS. IF THE CIRCUIT BREAKER IS
Figure 2-3 Rear View Showing Current Sensor Rating Through Viewing Window
NOT PROPERLY SEATED ON THE EXTENSION RAILS, IT COULD FALL FROM THE RAILS CAUSING EQUIPMENT DAMAGE AND/OR BODILY INJURY.
Carefully lower the circuit breaker down onto the exten­sion rails. Be certain that the circuit breaker’s four mold­ed drawout rail supports are fully seated in the exten­sion rail cutouts on both sides (Figure 2-4). Do not
remove the lifting yoke from the circuit breaker until it is properly seated on the rails.
Once the circuit breaker is on the extension rails and the lifting yoke is removed, proceed with the rest of the cir­cuit breaker installation.
2-6.1 REJECTION INTERLOCKS
Within any one physical frame size Magnum type dra­wout circuit breakers come in a variety of continuous current and interruption ratings, some of which are incompatible with others. Double wide circuit breakers also come with several phase sequence options which are also incompatible. To prevent the insertion of cir­cuit breakers with (1) inadequate interrupting capability, (2) with physically incompatible primary disconnects or (3) with an incompatible phase sequence, rejection interlock key plates are provided on both the circuit breaker and cassette. The key plate on the circuit breaker is pre-assembled at the factory; but the cas­sette-side rejection plate and key pattern must be assembled and installed by the switchboard builder.
!
CAUTION
Figure 2-4 One Side of Drawout MDS/MDSX Circuit Breaker Properly Seated on Extension Rail
Molded Rail Supports
Extension Rail Cutout
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DO NOT DISABLE REJECTION INTERLOCKS. DOING SO AND USING A LOWER CAPACITY CIR­CUIT BREAKER IN AN INCOMPATIBLE CASSETTE COULD RESULT IN AN ELECTRICAL FAULT WHICH COULD RESULT IN DEATH, BODILY INJURY AND/OR EQUIPMENT DAMAGE.
The rejection interlocks are steel pins in the floor of the circuit breaker cassette. As the circuit breaker is pushed into the structure, the mating pins on the bottom of the circuit breaker move past a set of corresponding pins in the cassette, if the circuit breaker and cassette are compatible. If the circuit breaker and the cassette are mismatched, the rejection pins will block the inser­tion of the circuit breaker into the cassette before the levering-in mechanism is engaged.
Before attempting to push the circuit breaker into the DISCONNECT position, compare the positioning of rejection interlock pins in the cassette in keeping with Table 2.2 and Figure 2-5 and the information supplied on the circuit breaker’s nameplate. Proceed if the circuit breaker and cassette are compatible.
2-6.2 CIRCUIT BREAKER POSITIONING
Magnum DS, DSX and DSL drawout circuit breakers have four normal positions:
• REMOVE (Withdrawn) (Figure 2-6)
• DISCONNECT (Figure 2-7)
• TEST (Figure 2-8)
• CONNECT (Figure 2-9)
The REMOVE position is a position outside the com­partment on the cassette’s drawout rails where the cir­cuit breaker is not engaged with the levering mecha
!
CAUTION
nism. The DISCONNECT, TEST, and CONNECT, posi­tions are reached by means of the levering mechanism.
With the breaker solidly positioned on the cassette’s extension rails and the levering-in mechanism in the DISCONNECT position, carefully and firmly push the circuit breaker into the compartment as far as it will go. The outer (recessed) portion of the circuit breaker face plate should align with the GREEN target line (labelled DISC) on the inside top left wall of the cassette (Figure 2-10).
Figure 2-5 Cassette Rejection Interlock Pin Positioning/Installation
From Table 2.2, make a pin location comparison. Stop nuts should be torqued to 8-10 Ft.-Lb.
Table 2.2 Rejection Interlock Pin Locations
1
2
3
4
5
6
7
8
Pin Locations
Cell For: 1 2 3 4 5 6 7 8
MDN-408, 412, 416
MDN-508, 512, 516
MDN-608, 612, 616
MDS-408, 412, 416
MDS-508, 512, 516, 520
MDS-608, 612, 616, 620
MDS-808, 812, 816, 820
MDS-C08, C12, C16, C20
MDS-525
MDS-625, 630, 632
MDS-825, 830, 832
MDS-C25, C30, C32
MDS-840
MDS-84N
MDS-C40
MDS-C4N
MDS-E40
MDS-E4N
MDS-850, 860
MDS-85N, 86N
MDS-C50, C60
MDS-C5N, C6N
MDS-E50, E60
MDS-E5N, E6N
MDSL08
MDSL12
MDSL16
MDSL20
MDS-X08
MSD-X12
MDS-X16
MDS-X20
MDS-X3N
MDS-X4N
MDS-X5N
MDS-X32
MDS-X40
MDS-X50
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X-LG
X-LG
X-LG
X-LG
X-LG
X-LG
X-LG
X-LG
X-LG
X-LG
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
NOTE: X-LG IN TABLE 2.2 DENOTES LONG LENGTH STOP NUT 0.760 INCHES LONG
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Page 8
■ No Electrical Connections Made
■ Breaker On Extension Rails
■ Remove or Inspection Position
Circuit
Breaker
Side View
Secondary
Connection Not Made
Rear of Compartment
Primary Connections Not Made
Compartment
Front Door
Circuit Breaker Out of Compartment On Extension Rails
Secondary
Connection
Not Made
Circuit
Breaker
Side View
Rear of Compartment
Primary Connections Not Made
Compartment
Front Door
■ Only Ground Connection Made
■ Breaker Still Behind Door
■ Typical Storage Position
Circuit
Breaker
Side View
Secondary
Connection Made
Rear of Compartment
Primary Connections Not Made
Compartment
Front Door
■ Breaker and Trip Unit Testing
■ Primary Connection Not Made
■ Secondary and Ground Connections Made
Figure 2-6 Remove Position
Figure 2-7 Disconnect Position
Figure 2-8 Test Position
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Page 9
Circuit
Breaker
Side View
Rear of Compartment
Primary Connections Made
Secondary
Connection Made
Compartment
Front Door
■ Full Breaker Operation
■ Primary, Secondary and Ground Connections Made
■ Fully Racked into Cassette (Compartment)
Figure 2-9 Connect Position
2-6.3 LEVERING CIRCUIT BREAKER
MAKE CERTAIN THAT THE CIRCUIT BREAKER IS FULLY INSERTED INTO ITS COMPARTMENT BEFORE ANY ATTEMPT IS MADE TO LEVER THE CIRCUIT BREAKER. ATTEMPTING TO LEVER THE CIRCUIT BREAKER IN BEFORE IT IS FULLY POSI­TIONED INSIDE ITS COMPARTMENT CAN RESULT IN DAMAGE TO BOTH THE CIRCUIT BREAKER AND THE COMPARTMENT.
The circuit breaker is now ready to be levered. With the circuit breaker OPEN, the levering device access door can be raised. The levering device is hand operated using a standard 3/8” square drive and ratchet, which is not provided (Figure 2-11). As long as the access door is raised, the circuit breaker is held trip free. Begin by rotating the levering-in screw to the full counterclock­wise (DISCONNECT) position.
Close the compartment door and begin levering the breaker into its different positions using a clockwise ratcheting motion. When the circuit breaker is levered fully to the DISCONNECT or CONNECT position the levering shaft hits a hard stop; do not exceed 25 ft.lb. of torque or the levering mechanism may be damaged.
The circuit breaker can be levered with the compart­ment door open or closed, but it is advisable to close the door prior to levering. The position of the
circuit breaker within its compartment is indicated by color coded position indicators (Red = Connect, Yellow = Test, Green = Disconnect) (Figures 2-11 and 3-5). To remove the circuit breaker from its compartment, follow the procedure just described using a counterclockwise ratcheting motion.
Figure 2-10 Cassette Label Showing Disconnected, Test and Connected Position of Recessed Cover
!
CAUTION
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Page 10
Figure 2-12 Typical Fixed Magnum DS Circuit Breaker
The circuit breaker mechanism is interlocked such that charged closing springs are automatically dis­charged if the circuit breaker is levered into or out of the cell. Discharge takes place between the DIS­CONNECT and TEST position.
2-7 FIXED CIRCUIT BREAKER
Magnum DS fixed type circuit breakers differ from the drawout version in that it has no levering device, primary disconnects and secondary disconnects (Figure 2-12). In addition, a fixed circuit breaker does not have a stan­dard feature to hold the breaker in a trip-free position. To ensure the proper sequence of operation between two or more circuit breakers, an optional key interlock is mounted through the front panel (Figure 3-44).
FAILURE TO COMPLY WITH INSTALLATION OF THE FIXED MOUNTED MDSX ARC HOOD ASSEM­BLY COULD RESULT IN EQUIPMENT DAMAGE, BODILY INJURY OR EVEN DEATH.
The MDSX fixed mounted breaker is shipped with an included arc hood assembly. This assembly is required to be installed on the top of the breaker prior to the unit being placed in service.
Circuit breaker terminals have holes for making bolted horizontal primary bus connections. Adapters are avail
Mounting Foot
Figure 2-11 Levering Position Indication
NOTICE
able for making vertical primary bus connections. Secondary connections can be made through standard terminal blocks or a special connector compatible with the drawout circuit breaker’s type secondary connector. Both secondary connection devices are mounted at the top front of the circuit breaker.
The fixed circuit breaker frame has two mounting feet, one on each side, to permit the fixed circuit breaker to be securely mounted. Each mounting foot has two slot­ted mounting holes which are used to bolt the circuit breaker securely in place. Use either M10 or 3/8” bolts for this purpose. Refer to the dimensional drawings referred to in Section 5 (Fixed Circuit Breakers) for cir­cuit breaker and bus stab dimensions.
Refer to the circuit breaker weights in Table 2.1 to ensure that the panel on which a fixed circuit break­er is to be mounted is capable of supporting the weight.
2-8 CIRCUIT BREAKER OPERATION
Circuit breakers should be operated manually and/or electrically before they are put into service. This can be done during the installation process or some later date prior to start-up. To check circuit breaker operation, fol­low the operational procedures outlined in Section 3 for both manually operated and electrically operated circuit breakers.
NOTICE
!
WARNING
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CONNECT
CONNECT
TEST
TEST
DISCONNECT
DISCONNECT
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Instruction Book
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Effective: May 2006
SECTION 3: CIRCUIT BREAKER DESCRIPTION AND OPERATION
3-1 INTRODUCTION
Magnum DS (MDS), DSX (MDSX) circuit breakers are available in both drawout and fixed mounting configura­tions (Figures 3-1 and 3-2). Magnum DSL (MDSL) cir­cuit breakers with integral current limiters are available only in a drawout configuration (Figure 3-3). A majority of features are common to all configurations, and will be discussed in this section. The mounting features unique to the drawout and fixed configurations will be covered individually in Sections 4 and 5 respectively.
Controls and indicators for both drawout and fixed circuit breakers are functionally grouped on the front of the cir­cuit breaker. The front escutcheon (faceplate) is com­mon for all Magnum frame sizes up through 5000 amperes.
Double Wide DS and DSX frame circuit breakers utilize
six (or eight) sets of rear primary connections; these cir­cuit breakers are available from the factory with several different phase sequences, distinguishable by the sixth character in the model number. The phase sequence is also labeled on the rear of the circuit breaker (Figure 3-4). For these DS and DSX drawout breakers, phase sequence labels are also supplied with the cassette and must be applied by the switchgear builder. Circuit brak­ers with different phase sequences are not interchange­able. DS and DSX drawout breakers with differing phase sequence are prevented from insertion into the cassette by properly assembled rejection key plates (see section 2-6.2).
The Magnum DSL (MDSL) drawout circuit breaker is available only in a 3-pole single wide standard configu­ration. The MDSL is a coordinated combination of a standard Magnum DS circuit breaker and series con­nected current limiters. The primary purpose of the cur­rent limiters is to extend the interrupting rating of the MDS circuit breaker up to 200,000 amperes.
Figure 3-1 Typical MDS /MDSX Drawout Circuit Breaker Features (Front and Rear Views)
Baffled Arc Chute Cover
Secondary Disconnects (Contacts)
Faceplate (Front Cover)
Drawout Rail Supports
Integral Lifting Handle
5
2
1
6
7
9
4
3
8
10
Primary Disconnect Finger Cluster
Arc Chamber
Primary Vertical Adapter
Sensor Rating Viewing Window
Levering Device Bearing Plate
Padlockable Levering Device Access Door
Circuit Breaker Nameplate
11
12
1
12
3
4
4
5
5
6
6
7
8
9
10
10
11
12
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Figure 3-2 Typical MDS/MDSX Fixed Circuit Breaker Features (Front and Rear Views) (MDSX shown without required arc hood)
Baffled Arc Chute Cover
Secondary Disconnect
Faceplate (Front Cover)
Integral Lifting Handle
5
2
4
3
Fixed Horizontal Primary Terminal
Fixed Primary Terminal (with optional Vertical Adapter)
Arc Chamber
Sensor Rating Viewing Window
Mounting Foot
6
7
8
9
10
1
1
2
3
4
4
5
6
7
8
9
9
10
Figure 3-3 Typical MDSL Drawout Circuit Breaker Features (Front and Rear Views)
7
8
10
9
11
Arc Chamber
Integral Current Limiter
Levering Device Bearing Plate
Padlockable Levering Device Access Door
Circuit Breaker Nameplate
Baffled Arc Chute Cover
Secondary Disconnects (Contacts)
Faceplate (Front Cover)
Breaker Rollers
Integral Lifting Handle
Primary Disconnect Finger Cluster
5
2
1
4
3
6
1
2
3
4
5
6
7
8
9
9
10
11
4
4
4
1
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7
2
1
4
3
5
6
Baffled Arc Chute Cover
Secondary Contact Connector
Faceplate (Front Cover)
Integral Lifting Handle
Fixed Vertical Primary Terminals with Optional Vertical Adaptor
Arc Chamber
Mounting Foot
Circuit Breaker Nameplate
Phase Identification Labels
Figure 3-4 Typical Double-wide MDS/MDSX Standard Frame Fixed Circuit Breaker Features (Front and Rear Views) (MDSX shown without required arc hood)
8
9
1
1
2
3
4
4
5
6
7
7
8
9
9
9
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Figure 3-5 Typical Magnum DS/DSX Drawout Circuit Breaker Front Cover
Trip Flag (Pop Out Indicator)
Three Accessory Windows
Trip Unit
Rating Plug
Contact Status (Open-Close)
Spring Status (Charged-Discharged)
2
1
4
3
6
2
1
8
7
10
3
9
11
12
Manual “OFF” Button (Push)
Manual “ON” Button (Push)
Manual Charge Handle
Optional Operation Counter
Padlockable Levering Device Access Door for Drawout Breaker
5
8
7
Color Coded-Breaker Position Indicator
Nameplate
Trip Unit Test Port
Trip Unit Cover with Two Mounting Screws (Mounting Screws will Accept Customer Supplied Lead Security Meter Seals
10
9
11
(Red)
(Green)
(Yellow)
(White)
(Green)
(Red)
5
13
14
12
13
4
14
15
6
15
Red = Connect
Yellow = Test
Green = Disconnect
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CLOSED
OPEN
CHARGED
DISCHARGED
PUSH ON
PUSH OFF
CONNECT
CONNECT
TEST
TEST
DISCONNECT
DISCONNECT
3-2 BASIC CIRCUIT BREAKER ASSEMBLY
All Magnum circuit breakers use a rigid frame housing construction of engineered thermoset composite resins. This construction provides high strength structural prop­erties, excellent dielectric characteristics and resistance to arc tracking.
The 3-piece construction approach provides support while isolating and insulating power conductors (Figure 3-6):
(1) A 2-piece engineered thermoset composite resin
case encloses current paths and arc chambers. The chambers act to channel arc gases up and out of the cir­cuit breaker during interruption.
(2) The operating mechanism sits on the front of the
case and is electrically isolated and insulated from cur­rent contact structures. It is covered by an insulating front cover.
3-3 POLE UNITS
A current carrying pole unit is individually enclosed and rigidly supported by the case. The individual chambers provide for pole unit isolation and insulation from one another. Each pole unit has one primary contact assembly, which consists of a moving portion and a fixed portion. The exact design configuration depends upon the breaker’s frame size. Circuit breakers with frame sizes of 4000 amperes and higher use two pole units and arc chute assemblies connected mechanically and electrically in parallel to form one phase.
I.B. 2C12060H08
Instruction Book
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Effective: May 2006
Figure 3-6 Typical Magnum Construction (Right Side View)
2
1
3-1.1 MDSL APPLICATION/OPERATION
MDSL circuit breakers are intended for applications requiring the overload protection and switching functions of air circuit breakers on systems whose available fault currents (1) exceed the interrupting ratings of the circuit breakers alone and/or (2) exceed the withstand and interrupting ratings of downstream circuit components.
The 800 through 2000 amp frame MDSL circuit break­ers have integrally mounted limiters on the drawout breaker element. On overloads and faults within the cir­cuit breaker interrupting rating, the circuit breaker pro­tects the limiters. On higher fault currents exceeding the circuit breaker rating, the limiters protect the circuit breaker.
Interlock arrangements trip the circuit breaker whenever any limiter blows. The circuit breaker cannot be reclosed on a live source unless there are three unblown limiters on the circuit. The blown fuse indica­tor, located on the front of the circuit breaker, provides a visual indication when a current limiter in any phase has interrupted a short circuit. In addition, a blown limiter sensing circuit insures that a circuit breaker will be tripped when any current limiter has blown, preventing single phasing.
The MDSL circuit breaker must be completely with­drawn from its compartment onto the compartment’s extension rails, thus assuring complete isolation, before the integral current limiters are accessible.
Additional information concerning current limiter ratings, limiter replacement and blown fuse operation is provid­ed later in this chapter.
2
1
Figure 3-7 Features of Magnum Moving Conductor Assembly
Pivot Point
Single Contact
Finger
Moving
Arcing
Contact
Area
(Toe)
Moving Main Contact
Conductive Pad
(Heel)
Dual Flexible Connections
(Case)(Front Cover)
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Figure 3-9 Standard Frame DS (12-finger) Moving Conductor Assembly
Figure 3-10 General Partial Cross-Sectional View (Shown in Closed Position) (not specific to any family/frame)
3-3.1 PRIMARY MOVING CONTACTS
Depending upon the frame size, each primary moving contact assembly is comprised of multiple individual copper contact fingers connected to the load conductor through flexible braided connectors (Figure 3-8). Two flexible connectors are used to connect each finger to the load conductor. The number of fingers used depends upon the circuit breaker’s continuous and short-circuit current ratings (Figures 3-8 and 3-9). On some ratings fingers are removed and replaced with spacers.
The single contact finger performs both the main and arcing contact functions on different parts of the same finger (Figure 3-7). A highly conductive alloy pad is part of the contact finger and functions as the moving main contact, and is called the “Heel.” The tip of the same contact finger functions as the moving arcing contact, and is called the “Toe.”
In addition to the contact finger information given above, DSX (MDSX) utililize an inner and outer carriage design to facilitate a fast opening blow open contact structure (Figure 3-9a). The contact fingers mounted in the inner contact carrier can move independently from both the outer carrier and the opening mechanism in the breaker. This independence is the core design feature of its fast opening blow open contact structure.
Figure 3-8 Narrow Frame (8-finger) Moving Conductor Assembly
“Heel” (Main Contact)
“Toe” (Arcing Contact)
“Toe” (Arcing Contact)
“Heel” (Main Contact)
Figure 3-9a MDSX Moving Contact Assembly
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Breaker
Front
Arc Chute
Integral
Moving Contact Fingers
Moving Contact Springs
Breaker
Bottom
xxxxxxxx x x xxxxxxxx
xxxxxxxx x x xxxxxxxx
x x
x x
Arc Runner
Arcing Contact (Toe)
Line Conductor
Current Flow
Stationary Main Contact
Moving Main Contact (Heel)
Current Flow
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Instruction Book
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Effective: May 2006
complete the manual charging process. It is possible to manually recharge the spring immediately after closing the circuit breaker and before it has been tripped open.
Standard manually operated circuit breakers are closed and opened by hand using the Manual “ON” and Manual “OFF” buttons respectively located on the front of the cir­cuit breaker (Figure 3-5). Performing either operation is accomplished by pressing and releasing the appropriate button. Access to these pushbuttons can be limited by the use of an optional, padlockable cover. In addition, complete access to the “ON” button can be prevented with an optional prevent close cover. The status of the springs and the primary contacts are always indicated in an indicator window just above the pushbuttons.
Electrically operated optional devices are available to automatically close or trip a manually operated circuit breaker. An electrical spring release is available to close a manually operated circuit breaker. Two optional devices, a shunt trip and an undervoltage release, are available to automatically trip (open) a manually operated circuit breaker. All of these UL listed optional devices can be installed easily in the field. For more details on these devices, refer to paragraph 3-8 in this manual.
An electrical operator which is used to charge the closing spring automatically can be added to a manually operat­ed circuit breaker in the field (Figure 3-13). Manually operated circuit breakers are pre-wired to accept this addition.
3-3.2 PRIMARY STATIONARY CONTACTS
The primary stationary contact is a combination of two items (Figure 3-10). One is a conductive pad mounted on the line conductor which functions as the stationary main contact. The other is an arc runner, also connect­ed to the line conductor. The integral arc runner serves a dual purpose:
• Fixed arcing contact
• Part of the arc chute
3-4 OPERATING MECHANISM
The Magnum DS/DSX/DSL operating mechanism is based on the proven cam and spring design of the DSII power circuit breaker. It is easily accessed by removing four cover screws and the front cover (Figure 3-11). The mechanism is a two-step stored energy mecha­nism. Potential energy is stored to close the circuit breaker. Sufficient energy to open the circuit breaker remains available after a closing operation.
3-4.1 MANUAL OPERATION
On manually operated circuit breakers, the closing spring can only be charged manually. To manually charge the spring, insert one finger in the recess behind the charging handle and pull out. This permits a gloved hand to grasp the handle and begin charging (Figure 3-12). It takes from 5 to 7 downward strokes on the charging handle to
Figure 3-11 Typical Electrically Operated Drawout MDS/MDSX Circuit Breaker with Front Cover Removed
Secondary Wiring Points
Field Installable Accessories (3 maximum)
Trip Unit
Electric Charging Motor
Manual Charge Handle
Operations Counter (optional)
Padlockable Levering Device Access Door
Breaker Position Indicator
7
2
1
4
3
5
6
8
2
1
3
5
6
7
8
4
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