GE Industrial Solutions Power-Vac ML-20 Mechanism User Manual

DEH 40368 Instructions

PowerVac

Vacuum Circuit Breaker

with ML-20 Mechanism

PowerVac ® Vacuum Circuit Breaker

with ML-20 Mechanism

Table of Contents

Description Page

SECTION 1−−−−Introduction

1.1 Safety.............................................................................. 4

1.2 Maintenance ................................................................... 4

............................................ 4

SECTION 2−−−−Description

2.1 General............................................................................ 5

2.2 Summary Description...................................................... 5

............................................... 5

SECTION 3−−−−Receiving, Handling and

Storage

3.1 Receiving ........................................................................ 5

A. Equipment Packages................................................. 5

B. Inspecting for Damage .............................................. 5

C. Filing a Claim............................................................. 5

3.2 Handling.......................................................................... 6

3.3 Storage............................................................................ 6

...................................................... 5

SECTION 4−−−−Features

4.1 Safety Precautions........................................................... 6

4.2 Interlocks......................................................................... 6

4.2.1 Rating Interference Plate................................................. 6

4.2.2 Closing Spring Interlock................................................... 6

4.2.3 Negative Interlock............................................................ 7

4.2.4 Positive Interlock Bar....................................................... 7

4.2.5 Closing Spring Gag Interlock............................................ 7

...................................................... 6

SECTION 5−−−−Operation

5.1 General............................................................................ 8

5.2 Close Spring Charging..................................................... 8

5.3 Closing Operation............................................................ 8

5.4 Opening Operation.......................................................... 9

5.5 Trip-free Operation.......................................................... 9

.................................................. 8

SECTION 6−−−−Control Circuit

....................................... 9

SECTION 7−−−−Mechanical Checking and Slow Closing

7.1 Visual Inspection.............................................................. 9

7.2 Closing Spring Charging .................................................. 9

7.3 Closing Spring Gag..........................................................10

7.4 Slow Closing....................................................................10

7.5 Gag Plate Removal..........................................................10

SECTION 8−−−−Dimensional Checks

8.1 Primary Contact Erosion ..................................................11

8.2 ML Wipe Spring Compression ........................................11

8.3 Contact Gap ....................................................................11

8.4 Close Coil Plunger Gap....................................................12

8.5 Trip Coil Plunger Gap.......................................................12

8.6 Control Switch Adjustment..............................................12

......................................... 9

.........................11

Description Page

SECTION 9−−−−Electrical Checks

9.1 Electrical Operation.........................................................14

9.2 High Potential Test.......................................................... 14

9.2.1 Primary Circuit................................................................. 14

9.2.2 Secondary Circuit ............................................................14

9.3 Primary Circuit Resistance .............................................. 14

9.4 Vacuum Interrupter Integrity Test....................................14

9.5 Insulation Test.................................................................15

SECTION 10−−−−Checking and Installing

SECTION 11−−−−Maintenance

11.1 General ...........................................................................17

11.1.1 PowerVac Interrupter......................................................17

11.1.2 Trouble Reporting...........................................................17

11.2 Service Conditions ..........................................................17

11.3 Fault Interruptions........................................................... 17

11.4 Contact Erosion...............................................................17

11.5 Transfer Finger Wear...................................................... 17

11.6 Mechanism..................................................................... 17

11.7 Primary Insulation Parts...................................................17

11.8 Lubrication ......................................................................18

11.9 Recommended Maintenance.......................................... 18

SECTION 12−−−−Timing SECTION 13−−−−Opening and Closing Speed SECTION 14−−−−Repair and Replacement

14.1 General ...........................................................................21

14.2 Replacement of Interrupter Asse m blies......................... 21

14.3 Primary Disconnect Fingers ............................................21

14.4 Mechanism..................................................................... 21

14.5 Control Switches.............................................................21

14.6 Trip Coil Replacement..................................................... 21

14.7 Closing Coil Replacement...............................................22

14.8 Auxiliary Switch Replacement.........................................22

14.9 Motor Replacement........................................................22

14.10 “Y” Relay Replacement................................................... 22

SECTION 15−−−−Renewal Parts

15.1 Ordering Instructions....................................................... 23

SECTION 16−−−−Mechanical Adjustment

16.1 General ...........................................................................23

16.2 Wipe Adjustment............................................................ 23

16.3 Contact Gap Adjustment.................................................23

16.4 Trip Coil Plunger.............................................................. 24

16.5 Close Coil Plunger...........................................................24

16.6 Close Spring Discharge Interlock.....................................24

16.7 Negative Interlock........................................................... 24

INDEX

........................................................................................ 36

Trouble Reporting Form................................................................37

Breakers

.................................14

.................................................16

.......................................17

......................................................19

..20

...........21

....................................23

............23

List of Illustrations

Figure Page

1 Front view of PowerVac® breaker with front cover .................... 6

2 Rating interference plate........................................................... 6

3 Front view of PowerVac breaker without front cover................ 8

4 Manual charging........................................................................ 9

5 Gag plate installation.................................................................10

6 Operating rod assembly............................................................10

7 Contact gap...............................................................................11

8 Close coil plunger gap...............................................................12

9 Trip coil plunger gap..................................................................12

10 Control switches.......................................................................13

11 Sample operating speed graphs................................................19

12 Contact gap adjustment ............................................................ 20

13 Spring discharge interlock .........................................................24

14 Toggle linkage positions of the ML-18 mechanism ...................25

15 Schematic of ML-18 mechanism...............................................27

16 Typical wiring diagram for ML-18 mechanism...........................29

17 PowerVac 18 PowerVac

19 Trip coil and linkage...................................................................31

20 Close coil linkage.......................................................................32

21 Bottom view of the ML-18 mechanism.....................................33

22 Negative interlock.....................................................................34

23 Wipe spring compression..........................................................34

THESE INSTRUCTIONS ARE INTENDED FOR USE BY QUALIFIED PERSONNEL FOR INSTRUCTION AND MAINTENANCE PURPOSES. REPRODUCTION IN WHOLE OR IN PART IS NOT PERMITTED WITHOUT TH E EX PRESS PERMISSION OF GENERAL ELECTRIC.

breaker left-front view ............................................30

breaker right-rear view............................................30

Table Page

1 Control Device and Voltage..................................................... 18

2 Measurements .......................................................................35

3 Adjustments............................................................................ 35

PowerVac ® Vacuum Circuit Breaker

with ML-20 Mechanism

SECTION 1—Introduction

This manual provides the information needed by the user to properly install, operate and maintain the ML-20 PowerVac Breaker.

The PowerVac interrupting element for use in metalclad switchgear to provide protection and control of electrical apparatus and power systems. To the extent required applicable ANSI, IEEE and NEMA Standards are met. No such assurances are given with respect to local codes and ordinances, as they vary greatly.

vacuum breaker is a horizont al drawout

1.1—Safety

Each user must maintain a safety program for the protection of personnel, as well as other equipment, from the potential hazards associated with electrical equipment.

The following requirements are intended to augment the user's safety program, but NOT supplant the user's responsibility for devising a complete safety program. The following basic industry practiced safety requirements are applicable to all major electrical equipment such as switchgear or switchboards. GE neither condones nor assumes any responsibility for practices which deviate from the following:

1. ALL CONDUCTORS MUST BE ASSUMED TO BE ENERGIZED UNLESS THEIR POTENTIAL HAS BEEN MEASURED AS GROUND AND ADE Q UATE CAPACITY GROUNDING ASSEMBLIES HAVE BEEN APPLIED TO PREVENT ENERGIZING. Many accidents have been caused by unplanned energization from non-recognized back feeds, equipment malfunctions, and from a wide variety of sources.

2. It is strongly recommended that all equipment be completely de-energized, verified to be “dead”, then grounded with adequate capacity grounding assemblies prior to any maintenance. The grounding cable assemblies must be able to withstand energizing fault levels so that protective equipment may clear the circuit safely. Additional discussion on this concept is covered in Chapter 20 of ANSI/NFPA 70B, Electrical Equipment Maintenance.

3. Although interlocks to reduce some of the risks are provided , the individual's actions while performing service or maintenance are essential to prevent accidents. Each person's knowledge; mental awareness; and planned and executed actions often determine if an accident will occur. The most important method of avoiding accidents is for all associated personnel to carefully apply a thorough under-standing of the specific equipment from the viewpoints of its purpose, its construction, its operation and the situations which could be hazardous.

All personnel associated with installation, operation and maintenance of electrical equipment, such as power circuit breakers and other power handling equipment, must be thoroughly instructed, with periodic retraining, regarding power equipment in general as well as the particular model of equipment with which they are working.

Instruction books, actual devices and appropriate safety and maintenance practices such as OSHA publications, National Electric Safety Code (ANSI C2), National Electric Code, and National Fire Protection Association (NFPA) 70B Electrical Equipment Maintenance must be closely studied and followed. During actual work, supervision should audit practices to assure conformance.

1.2—Maintenance

Excellent maintenance is essential for reliability and safety of any electrical equipment. Maintenance programs must be tuned to the specific application, well planned and carried out consistent with both industry experience and manufacturer's recommendations. Local environment must always be considered in such programs, including such variables as ambient temperatures, extreme moisture, number of operations, corrosive atmosphere or major insect problems and any other unusual or abusive condition of the application. One of the critical service activities, sometimes neglected, involves the calibration of various control devices. These monitored conditions in the primary and secondary circuits, sometimes initiating emergen cy corrective action such as opening or closing ci rcuit breakers. In view of the vital role of these devices, it is important that a periodic test program be followed. As was outlined above, it is recognized that the interval between periodic checks will vary depending upon environment, the type of device and the user's experience.

It is the GE recommendation that, until the use r has accumulated enough experience to select a test interval better suited to the individual requirements, all significant calibrations be checked at an interval of one to two years.

To accomplish this, some devices can be adequately tested using test sets. Specific calibration instructions on particular devices typically are provided by supplied instruction books.

Instruction books supplied by manufacturers address components that would normally require service or maintenance during the useful life of the equipment. However, they can not include every possible part that could under adverse environments. Maintenance personnel must be alert to deterioration of any part of the supplied switchgear, taking actions, as necessary to restore it to serviceable status.

Industry publications of recommended maintenance practices such as ANSI/NFPA 70B, Electrical Equipment Maintenance, should be carefully studied and applied in each user's formation of planned maintenance.

Some users may require additional assistance from GE in the planning and performance of maintenance. Local GE Sales can be contracted to either undertake maintenance or to provide technical assistance such as the latest publications.

The performance and safety of all equipment may be compromised by the modification of supplied parts or their replacement by non-identical substitutes. All such design changes must be qualified to the original manufacturers specifications.

The user should methodically keep written maintenance records as an aid in future service planning and equipment reliability improvement. Unusual experiences should be promptly communicated to GE.

SECTION 2—Description

2.1—General

This section contains a description of the PowerVac® vacuum circuit breaker. It also describes the functions of the electrical and mechanical systems.

2.2—Summary Description

The PowerVac power interrupters to establish and interrupt a primary circuit. Primary connections to the associated metalclad switchgear are made by horizontal bars and disconnect fingers, electrically and mechanically connected to the vacuum interrupters. Molded interrupter supports, one per phase on a three-phase circuit breaker, provide mountings for the primary bars, interrupters, current transfer fingers, and heat dissipation fins (where used). The operating mechanism provides direct motion at each phase location in order to move the movabl e contact of the vacuum interrupters from an ope n position to a spring-loaded closed position and then back to the open position on command.

vacuum circuit breaker uses sealed vacuum

The ML-20 mechanism is of the stored-energy type and use a gear motor to charge a closing spring. During a closing operation, the energy stored in the closing spring is used to close the vacuum interrupter contacts, compress the wipe springs which load the contacts, charge the opening springs, and overcome bearing and other friction forces, The energy then stored in the wipe springs and opening springs will open the contacts during an opening operation.

Closing and opening operations are controlled electrically by the metalclad switchgear or remote relaying. Mechanical control is provided by manual close and trip buttons on the circuit breaker. The closing spring may be manually charged, and a method for slow-closing the primary contacts is available. The mechanism will operate at the ac or dc voltage indicated on the circuit breaker nameplate.

Mechanical and electrical interlocks are provide d and are described in para 4.2, Interlocks

SECTION 3—Receiving, Handling and Storage

3.1—Receiving

A. Equipment Packages

Every package leaving the factory is plainly marked with the case number, requisition number, and customer’s order number. If the equipment has been split for shipment, the section numbers of the equipment enclosed in each shipping package are identified.

NOTE: To avoid loss of any parts when unpacking, the contents of each container should be car efully checked again st the packing list before discarding the packing material.

Contents of each shipping package are listed on the Master Packing List. In addition, this list includes the number of the shipping crate in which miscellaneous parts needed to install and operate equipment (such as hardware, contact lubricant, touch-up paint, breaker closing devices, etc.) are locate d. Normally, such devices are packed in a cardboard carton.

B. Inspecting for Damage

All equipment leaving the factory is carefully inspected and packed by personnel experienced in the proper handling and packing of electrical equipment. Upon receipt of any equipment, immediately perform a v isual inspection to ascertain if any damage has been sustained in shipping or if there are any loose parts.

C. Filing a Claim

If any damage is evident, or indication of rough handling is visible, file a claim for damage at once with the transportation company and notify the nearest GE Company Sales Office immediately. Information on damaged parts,

number, requisition number, etc., should accompany the claim.

part number, case

3.2—Handling

When lifting the breaker, use of the specially designed lift truck is recommended. If it is necessar y to lift the b reaker with a hoist use four 1/2 inch diameter hooks r ate d at least 500 pounds each. Lifting holes are provided in the four corners of the frame members. (See figure 2) Use a spreader wider than the breaker to prevent slings from contacting the interrupter supports.

3.3—Storage

It is recommended that the breaker be put immediately in its permanent location. If this is not possible, the following precautions must be taken to assure proper breaker storage.

1. The breaker should be protected against condensation, preferably by storing it in a warm dry room of moderate temperature such as 40° - 100°F. Circuit breakers for outdoor metalclad switchgear should be stored in the equipment only when power is available and the heaters are in operation to prevent condensation.

2. The breaker should be stored in a clean location, free from corrosive gases or fumes; particular care, for example, should be taken to protect the equipment from moisture and cement dust, as this combination is present at construction sites and has a very corrosive effect on many parts.

3. Rollers, latches, etc., of the operating mechanism should be coated with 0282A2048P009 grease to prevent rusting.

If the breaker is stored for any length of ti me, it should be inspected periodically to see that rusting has not started and to ensure good mechanical condition. Should the breaker be stored under unfavorable atmospheric conditions, it should be cleaned and dried out before being placed in service.

SECTION 4—Features

4.1—Safety Precautions

This circuit breaker uses powerful springs for energy storage.

WARNING: DO NOT WORK ON THE INTERRUPTERS OR THE MECHANISM UNLESS THE CIRCUIT BREAKER IS IN THE “OPEN” POSITION AND BOTH THE CLOSIN G AND OPENING SPRINGS ARE EITHER DISCHARGED OR GAGGED AND ALL ELECTRICAL POWER IS REMOVED.

These precautions are required to prevent accidental operation. Anyone working on the circuit breaker should be familiar with the contents of this instruction book.

4.2—Interlocks

Each PowerVac® vacuum circuit breaker is provided with the following interlocks:

4.2.1 Rating Interference Plate

This interlock (1, Figure 2) permits only a breaker with a matching continuous current, voltage and interrupting rating to be inserted into a metalclad compartment of identical rating.

6 7

Figure 1 Front view of PowerVac breaker

with front cover

1. Front cover 6. Manual charge lever

2. Cover mounting bolts 7. Counter

3. Manual trip button 8. Spring charge indication

4. Manual close button 9. Closing spring gag access

5. Nameplate 10. Open/Close indicator The circuit breaker has been shipped in the CLOSED position.

After removing packing material, open the breaker by pushing in firmly on the manual trip button (3, Figure 1), while keeping hands away from moving parts, and verify that the operation counter advances one count.

Closing and opening springs are now in their discharged positions. Check this by first pressing the manual close button, then the manual trip button. The indicator flags on the front of the breaker should show “OPEN” and “DISCHGD”. All mechanical and electrical checks should be completed before putting breakers in service.

Figure 2 Rating interference plate

1. Rating interference plate

2. Lifting locations (3/4” dia. hole at all four corners)

4.2.2 Closing Spring Interlock

This racking-track operated interlock (4, Figure 18) prevents racking into or out of the metalclad compartment a breaker that has the closing spring charged. This action is accomplished by a roller on the right side of the breaker mechanism which contacts the racking mechanism and discharges the closing spring, unless the brea ker is in the “DISCONNECT/TEST” position or the “CONNECT” position in the metalclad compartment. This interlock also opens the CL/MS switch in the motor circuit to prevent electrical charging of the closing spring when th e breaker is between the “DISCONNECT/TEST” and “CONNECT” position in the metalclad compartment.

4.2.3 Negative Interlock

The function of this racking-track operated interlock (5, Figure

17) is to remove the trip latch from the trip roller thereby preventing a closing operation. The interlock al so opens the LCS switch in the closing circuit thereby removing the close circuit power. The negative trip interlock is functional while the breaker is being moved between the “DISCONNECT/TEST” and “CONNECT” position and upon withdrawal from the metalclad compartment.

4.2.4 Positive Interlock Bar

This interlock will prevent the racking of a closed breaker into or out of a metalclad compartment. A linkage connected to the cross shaft extends a détent e angle (3, Figure 17) out through the left side of the mecha n ism frame when the

breaker contacts are in the closed position. If the breaker is in the “CONNECT” or “DISCONNECT/TEST” position in the metalclad the détente angle locks into the racking mechanism to prevent access to the hex section of the racking screw.

4.2.5 Closing Spring Gag Interlock

The interlock is provided to prevent a breaker that has a gagged closing spring from entering a metalclad unit. This function is accomplished by projecting an angle (1, Figure 17) out of the left front side of the mechanism when the closing spring is gagged. This angle will interfere with the racking mechanism and block entry into the metalclad unit when the Closing Spring Gag Access Door is open.

SECTION 5—Operation

5.1—General

The PowerVac power interrupters to establish and interrupt a primary circuit. Primary connections to the associated metalclad switchgear are made by horizontal bars and disconnect fingers, electrically and mechanically connected to the vacuum interrupters. Molded interrupter supports, one per phase on a three-phase circuit breaker, provide mountings for the primary bars, interrupters, current transfer fingers, and heat dissipation fins (where used). The operating mechanism provides direct motion at each phase location in order to move the lower contact of the vacuum interrupters from an open position to a spring-loaded closed position and then back t o the open position on command.

The ML-20 mechanism (Figure 15) is of the stored-energy type and uses a gearmotor to charge a closing spring. During a closing operation, the energy stored in the closing spring is used to close the vacuum interrupt er contacts, compress the wipe springs which load the contacts, charge the opening spring, and overcome bearing and other friction forces, The energy then stored in the wipe springs and opening spring will open the contacts during an opening operation.

5.2—Close Spring Charging

Figure 15 shows a front view of the ML-20 in a schematic form. The primary contacts are open and the closing spring is charged. The closing spring charging system consists of a closing spring (1, view B) mounted on the left side of the breaker and the electrical charging system mo unted on the right side of the breaker. Both compon ents are fastened to the cam shaft (2, view B). A manual charging system (3, view A) is provided so that the mechanism can be slow closed and the closing spring can be charged without electrical control power.

Spring charging is accomplished electrically by a rotating eccentric on the output shaft of the gear motor driving pivoted charging arms (4, view C) which oscillate about the centerline of a ratchet wheel (5, view C). A driving pawl (6, view C), mounted within the charging arms, oscillates with the charging arms. Starting from its rear-most position, as the charging arms rotate forward, a spring forces engagement of the driving pawl with a tooth of the ratchet wheel. The ratchet wheel is advanced by the rotating charging arms and pawl assembly. Advancement of one tooth spacing is pro vided for each oscillation of the system. The ratchet motion is restricted to one direction by a spring-loaded holding pawl that prevents the ratchet wheel from going backwards as the charging arms oscillate back to pick up the next tooth. Thirteen complete cycles of the charging arms are needed for a full charge of the closing spring. The efficient, compact gear motor accomplishes this action in about three seconds. When the charging cycle is complete, the ratchet wheel is positioned so

vacuum circuit breaker uses sealed vacuum

that three missing teeth adjacent to the driving pawl and any motor overspin will not drive the ratchet wheel, thus preventing damage to the system.

When the spring is completely charged, the assembly is retained in that position by the close latch, until it is desired to close the circuit breaker.

The closing coil cannot be electrically energized unless the closing spring is completely charged. This action is prevented by the 52/CHG switch in the closing circuit.

The manual charging system (3, view A) works directly on the cam shaft where a one-way clutch (7, view A), driven by a manual handle, provides rotation of the ratchet wheel. Manual pumping of the handle advances the ratchet wheel and the holding pawl prevents counter-rotation while the handle is returning for another stroke. Approximately eight complete strokes of the manual handle are required fo r one complete spring-charging operation. When the spring charge indicator (9, Figure 3) shows “CHARGED”, MANUAL CHARGING MUST BE DISCONTINUED TO AVOID MECHANISM DAMAGE.

5 4

9 6

Figure 3 Front view of PowerVac

breaker

without front cover

1. Upper interrupt connection 8. Counter

2. Interrupter support 9. Spring charge indication

3. Operating rod 10. Manual charge lever

4. Racking arm 11. Manual close button

5. Compartment track rollers 12. Test position handle for

6. Manual trip button secondary disconnects

7. Open/Close indicator 13. Closing spring gag access

5.3—Closing Operation

(refer to Figure 15)

By either energizing the close solenoid or depressing the manual close button, the close latch (8, view C) is rotated, releasing the closing spring (1, view B). This action releases the energy in the closing spring and transmits it to t he closing cam (9, view D) and closing roller (10, view D) and ca uses

12 3

8 11

the linkage to rise until the prop (11, view D) can slip under the close roller (10, view D) and hold the linkage in place. As the linkage moves, the output crank (12, view D) rotates the cross shaft (13, view D) which in turn rotates the phase bell cranks and compresses the two opening springs ( 15, view E) on poles 1 and 3, this closes the vacuum interrupters, and compresses the three wipe springs (16, view E) on each pole. The rotation of the cross shaft (13, view D) also changes the auxiliary switch (7, view D) position. The position flag on the front panel will then indicate “CLOSED”. After the breaker is closed, the charging motor is again energized and the closing spring is charged as described under “CLOSE SPRING CHARGING”. Spring charging is possible when the breaker is in the closed position because the linkag e is h eld in place by the prop.

5.4—Opening Operation (refer to Figure 15)

By either energizing the trip solenoid or depressing the manual trip button (23, view B), the trip latch (19, view D) is rotated, permitting the linkage to collapse and the vacuum

interrupter contacts to open under the force of the wipe springs (16, view E) and opening springs (15, view E). At the end of the opening stroke, the center phase wipe spring assembly hits a stop block on the frame that limits overtravel and rebound. Rotation of the cross shaft from the closed to the open position operates the auxiliary switch (17, view D) which opens the trip coil circuit. If the closing spring has been recharged, the linkage will be reset and the trip latch will be in place on the trip roller, ready for another closing operation.

5.5—Trip-free Operation

The linkage is mechanically trip free in any location on the closing stroke. Electrically energizing the trip coil while closing will, after the auxiliary switch contacts change position, rotate the trip latch and permit the circuit breaker to open fully.

The linkage will reset as in a normal open operation, and the closing spring will recharge as described under SPRING CHARGING.

SECTION 6—Electric Control circuit

A typical PowerVac® circuit breaker ML-20 mechanism wiring diagram is shown in Figure 16. Check the wiring diagram supplied with the actual circuit breaker for its wiring.

The close spring-charging motor circuit is established th rough the CL/MS (close latch monitor sw itch) switch if the close latch is reset the SM/LS (spring moto r limit switch) if the closing spring is discharged and the IL/MS (Negative Interlock Monitoring Switch). When the closing spring is charged, the SM/LS interrupts the circuit.

The close coil circuit is established through two normally closed 52Y relay contacts, and the latch-checking switch LCS, if the trip latch is reset. An auxiliary switch contact 52b is a l so in series with the close coil and closes when the breaker is

open and opens when the breaker is closed. During a close operation, cam rotation closes the SM/LS contact allowing the 52Y relay to be energized; opening its contact s in the close coil circuit and sealing itself in through one of its own contacts to the close signal. This seal-in actio n prevents re-closing on a sustained close command as the close signal must be removed to drop out the Y relay, and reestablish the close circuit, thereby providing an anti-pump feature.

Circuit breaker mounted auxiliary switch contacts not used in the control circuit are bought out for control and indication functions. The metalclad equipment may provide a breaker operated stationary auxiliary switch for additional contacts (3, 6 or 10 stages are available).

SECTION 7—Mechanical Checking and Slow Closing

7.1—Visual Inspection

Visually inspect the circuit breaker for any sig ns of damage or loose hardware.

7.2—Closing Spring Charging

Manually charge the breaker closing spring using the charging handle provided (1, Figure 4). The closing spring is charged by a ratcheting mechanism that advances by one ratchet tooth at a time. When the spring is fully charged and the spring load is held by the closing latch, the spring indicator (3, Figure 1) will change from “DISCHGD” to “CHARGED”, and a positive snap will be heard as the spring travels over center.

CAUTION: AFTER THE SPRING IS COMPLETELY CHARGED, AS INDICATED IN FIGURE 4, FURTHER FORCING CHARGING HANDLE MAY CAUSE DAMAGE TO THE CLOSING LATCH AND ITS ASSOCIATED PARTS.

Figure 4 Manual charging

1. Manual charging handle

2. Close spring gag hole

(shown in closed position)

3. Spring charge indication

Figure 5 Gag plate installation

1 Closing spring gag plate 2 Manual charging lever

7.3—Closing Spring Gag

Insert the closing spring gag plate (1 , Figure 5) by opening the closing spring gag hole cover and inserting the tip of the gag plate between the end of the spring and the spring g uide and engaging the détentes o n the gag plate into the slots in the closing spring guide. Note that when the closing spring guide is exposed for gagging, an interference a n gle is exposed on the left side of the breaker (1, Figure 17). With the closing spring in the gagged position, this angle will provide

interference preventing use of the lift truck and racking of the breaker element. No attempt should be made to alter, modify or otherwise make inoperative this safety feature. With the gag plate in position, depress the manual close button. This action will partially discharge the closing spring and also partially close the vacuum interrupter contacts. Do not energize the secondary control circuit at this time.

7.4—Slow Closing

To manually slow close the breaker contacts, install the closing spring gag, as described above, and push the manual close button (11, Figure 3). Then put the manual charge handle on the manual charge lever and move the handle up and down. The breaker will be fully closed when the spring charge indicator shows “CHARGED”.

CAUTION: WITH THE GAG PLATE INSTALLED, THE BREAKER CLOSED, AND OPENING SPRINGS CHARGED, THE BREAKER CAN BE TRIPPED AT FULL SPEED.

7.5—Gag Plate Removal

To remove the gag plate, the closing spring must be fully charged. If the spring charge indicator does not show “CHARGED” in the window, manually charge the spring until it does. Lift up and push in on the gag plate to clear the détentes on the gag plate from the slots in the closing spring guide. While holding the gag plate up, remove it from the opening. Close the gag hole cover. Fo r safety, first close the breaker by depressing the manual “CLOSE” button and then depress the manual “TRIP” button. All stored energy is now removed from the breaker.

Figure 6 Operating rod assembly

1. Erosion Marker 4. Hexagon projection 7. Clamp screws

2. Lock nut 5. Operating rod insulator 8. Interrupter movable contact rod

3. Lock washer 6. Coupling clamp

SECTION 8—Dimensional Checks

With the breaker closed and the gag pla te installed, perform the following dimensional checks.

8.1—Primary Contact Erosion

In the closed position, the erosion marker (1, Figure 6) below the bus bar is aligned with a reference mark on the interrupter’s movable stem. As contact erosion occurs, the erosion mark will move upward away from the erosion pointer. When the seribed band on the interrupter’s movable stem is completely above the top surface of the pointer, 1/8 inch erosion has occurred and the interrupter should be replaced.

8.2—ML-20 Wipe Spring Compression

With the breaker closed and the closing spring gagged, measure with a feeler gauge and record the distance between the bellville washer and the trunion between the bell crank arms.

8.3—Contact Gap

The method of measuring the contact gap is as follows: With the breaker in the open position, the closing springs charged, and the closing spring gag plate installed, apply a piece of masking tape to the surface of the operating rod insulator as shown in Figure 7. Using a reference block, make a mark on

the tape near the top on all th ree poles. It is also advisable to put a reference mark on the tape to identify to which pole the tape is applied. Remove the closing spring gag plate and close the breaker. Using the same procedure as above, re-mark the tape. This new mark will be near the bottom of the tape. Trip the breaker, remove the tapes and re-apply th em to a flat surface. Measure the distance between the two lines. A caliper will give an accurate reading of the contact gap,

Dimension G: The gaps must be between the 0.655 inch maximum at the center pole and 0.595 inch minimum at the outer poles. It is not necessary that all readings correspond. A typically adjusted breaker will have more gap and wipe on the center pole than on the outside poles.

The close coil and trip coil plunger gap dimensional checks are made in the operating mechanism which is accessible from the bottom. To accommoda te these checks, the breaker should be turned on its right side resting on two-by-four wood blocks. DO NOT use the portable breaker lift t r uck.

CAUTION: DO NOT ALLOW ANYTHING TO COME IN CONTACT WITH THE INTERLOCK ROLLER (4, Fig. 18) ON THE RIGHT SIDE OF THE MECHANISM.

Figure 7 Contact gap

8.4—Close Coil Plunger Gap

The close coil plunger gap is shown in Figure 8. With the closing spring discharged, operate the plung er to make certain that the plunger moves freely over its full stroke in the coil. To check the closing coil plunger gap t he breaker should be open and the closing spring charged and gagged. Depress the close plunger button until resistance is felt. The gap between the plunger button and the coil housing should be as follows:

8.5—Trip Coil Plunger Gap

The trip coil plunger gap is shown in Figure 9. With the breaker in the open position and the closing spring in the charged position, make certain that the trip linkage and trip shaft move freely over the full plunger t r avel. To check the trip coil plunger gap adjustment, t he breaker is to be closed with the closing spring discharged. Dimension T between the plunger button and the coil housing should be between 0.20 and 0.25 inch. This dimension is obtained when the trip plunger button is depressed until resistance is felt . If the breaker is equipped with an optional second trip coil, use same procedure.

Figure 8 Close coil plunger gap

Figure 9 Trip coil plunger gap

8.6—Control Switch Adjustment

The breaker is to be in the open position with the opening and closing springs discharged. This results in the control switch plungers being in the depressed position. The switches to be checked are shown in Figure 10. On the LCS and stacked switches (SM/LS & CHG), the plunger rod is to be recessed within the rear of the switch body and this recess is to be 0 to 1/32 inch. This is a visual check. No adjustment is required on the CL/MS or the IL/MS.

+ 28 hidden pages

GE Industrial Solutions Power-Vac ML-20 Mechanism User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

SECTION 5—Operation