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ON-LOAD TAP-CHANGER RMV-II 1500 A / 2000 A / 2500 AOperating Instructions

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The information provided and the arrangements agreed during processing of the relevant quotations and orders are strictly binding.

The original operating instructions were drawn up in German.

Content

© Maschinenfabrik Reinhausen 2010 2159612/00 EN VACUTAP® RMV-II 3

Content

1 Technical Data ............................................................................. 11

1.1 General Data........................................................................................... 11

1.2 Application Limits ....................................................................................12

1.3 Equipment Standard Features ................................................................13

2 Safety instructions...................................................................... 15

3 Description .................................................................................. 17

3.1 Design .....................................................................................................18

3.2 Operation ................................................................................................20

3.3 Tap Selector ............................................................................................21

3.4 Change-over Selector (Reversing or Coarse/Fine).................................22

3.5 Vacuum Interrupter..................................................................................23

3.6 By-Pass Switch .......................................................................................24

3.7 Monitoring System ..................................................................................25

3.8 Drive Mechanism/Cam Switch Assembly................................................27

3.8.1 Option................................................................................................................. 28

4 Installation ................................................................................... 29

4.1 Receiving, Handling and Storage............................................................29

4.2 Mechanical Set-up ..................................................................................30

4.2.1 Attaching the Oil Compartment .......................................................................... 304.2.2 Mounting the Drive Mechanism Air Compartment.............................................. 30

Content

4 VACUTAP® RMV-II 2159612/00 EN © Maschinenfabrik Reinhausen 2010

4.3 Electrical Connections ............................................................................ 31

4.3.1 Connecting the Tap Leads to the LTC ................................................................ 314.3.2 Connecting the Monitoring System and the Drive Mechanism........................... 31

4.4 Test Procedures...................................................................................... 32

4.4.1 Manual Test Procedures..................................................................................... 324.4.2 Motorized Test Operations ................................................................................. 334.4.3 Monitoring System Tests .................................................................................... 34

4.5 Oil Filling/Transformer Vacuum Processing............................................ 36

5 Maintenance-Free Schedules and Service................................37

5.1 Maintenance-Free Intervals .................................................................... 37

5.2 Taking the LTC out of Service................................................................. 38

5.3 Draining the Oil ....................................................................................... 38

5.4 Internal Examination ............................................................................... 39

5.4.1 Vacuum Interrupter Examination ........................................................................ 395.4.2 By-pass switch ................................................................................................... 47

5.5 Preparing the LTC for Service ................................................................ 48

6 Replacement of the Vacuum Interrupter ...................................51

6.1 Removing the Old Vacuum Interrupter Assembly................................... 51

6.2 Installing the New Vacuum Interrupter ................................................... 58

7 Dehydrating Breather Assembly................................................65

7.1 Receiving ................................................................................................ 65

7.2 Installation............................................................................................... 65

7.3 Operation ................................................................................................ 66

Content


7.4 Maintenance............................................................................................66

8 Vacuum Interrupter Monitoring (VIM) System.......................... 69

8.1 Vacuum Interrupter Monitoring System Description................................69

8.2 Evolution of Design .................................................................................70

8.3 Installation and Wiring.............................................................................71

8.4 In-Service Monitoring System Verification...............................................72

8.5 In-Service Monitoring System Trip (Lockout / 86RL)...............................72

8.6 Replacement, Spare or Upgrade Parts ...................................................73

8.7 Monitoring System Vintage Identification ................................................74

9 Spare parts List ........................................................................... 75

10 Appendix...................................................................................... 77

10.1 Drive Mechanism, Standard Mounting ....................................................77

10.2 Parts Designation: Drive Mechanism, Standard Mounting......................78

10.3 Drive Mechanism, Ground Level Mounting .............................................79

10.4 Parts Designation: Drive Mechanism, Ground Level Mounting...............80

10.5 RMV-II Load Tap Changer, Operational Sequence Schematic ..............81

10.6 Dehydrating Breather, Dimensional and Installation Details ...................82

10.7 Parts Designation: RMV-II Load Tap Changer, Vacuum Interrupter Assembly.................................................................83

10.8 RMV-II Load Tap Changer, Vacuum Interrupter Assembly.....................84

Content


10.9 Parts Designation: RMV-II Load Tap Changer, By-Pass Switch Assembly ...................................................................... 85

10.10 RMV-II Load Tap Changer, By-Pass Switch Assembly .......................... 86

10.11 Parts Designation: RMV-II Load Tap Changer, Cam Switch Assembly ............................................................................ 87

10.12 RMV-II Load Tap Changer, Cam Switch Assembly................................ 88

Figures


Figures

Figure 1 Three-phase RMV-II load tap changer ............................................17

Figure 2 Tap changer oil compartment ..........................................................18

Figure 3 Vacuum interrupter, schematic layout .............................................19

Figure 4 Typical RMV-II winding layout (LTC on position 16 L).....................20

Figure 5 Tap change from position 16 L to 15 L ............................................20

Figure 6 Tap selector, by-pass switch and change-over selector, three-phase assembly .....................................................................22

Figure 7 Vacuum interrupter, single-phase assembly....................................23

Figure 8 By-pass switch, single-phase assembly ..........................................24

Figure 9 Monitoring system schematic diagram ............................................25

Figure 10 Drive mechanism cam switch assembly, hinged door open showing monitoring system and handcrank.....................................27

Figure 11 Monitoring system. cover removed..................................................35

Figure 12 Mechanical test procedure for good vacuum...................................40

Figure 13 Vacuum interrupter contact erosion indicator ..................................41

Figure 14 Location of P2 & P3, solid bus bar connector removed...................42

Figure 15 Test circuits to be used for the Hi-Pot Test......................................45

Figure 16 Location of P2 & P3 busbars, solid and flexible bus bar connectors removed ........................................................................46

Figure 17 By-pass switch, single-phase assembly, location of P2 & P3 bus bars ...........................................................47

Figure 18 Measuring the by-pass switch arcing tip thickness..........................47

Figure 19 Dehydrating breather .......................................................................49

Figure 20 Vacuum interrupter assembly ..........................................................52

Figure 21 Removing the CT from the interrupter assembly .............................53

Figures


Figure 22 Loosen the lock hex nut on the operating rod bolt while holding the moving contact stem..................................................... 54

Figure 23 Use a 19 mm wrench to turn the bolt and a 24 mm wrench to hold the vacuum interrupter contact stem ................................... 55

Figure 24 Unscrew the clamp on top of the vacuum interrupter...................... 56

Figure 25 Remove the clamp completely ........................................................ 57

Figure 26 Drop bracket down .......................................................................... 57

Figure 27 Unscrew the vacuum interrupter completely ................................... 57

Figure 28 Screw by hand until the lock nut is reached.................................... 58

Figure 29 Bolt heads and nuts are aligned to bend locking tabs..................... 59

Figure 30 Reinstall clamp but do not tighten firmly yet.................................... 60

Figure 31 Viewing the sight hole in the upper right hand corner ..................... 61

Figure 32 Location for feeler gauge measurement between operating rod bolt (window) and drive dog of driftoff plate (anvil gap)............. 61

Figure 33 Anvil gap measurement, schematic representation ........................ 62

Figure 34 Adjustment of vacuum interrupter to the operating rod-bolt during feeler gauge measurement. ................................................. 63

Tables


Tables

Table 1 General data ...........................................................................................11

Table 2 Application Limits ....................................................................................12

Table 3 Annual checks.........................................................................................37

Table 4 Routine checks........................................................................................37

Table 5 Spare parts..............................................................................................75

1 Technical Data


1 Technical Data

The RMV-II load tap changer fulfills all requirements in IEC 60214-1 and ANSI/IEEE C57.131-1995.

The Motordrive Mechanism complies to IEEE C57.131-1995.

1.1 General Data

Design 3 phase, preventive autotransformer (reactor) switching prin-ciple (to break load current by vacuum interrupters)

Tank Will withstand full vacuum (± 15 psi)

Size (LxWxH) Tank:66 x 32 x 50 in.for 69 kV design, 66 x 29 x 43 in. for 15 and 25 kV designAir compartment:34 x 17 x 23.5 in. (250 lbs)

Total weight (incl. oil) 5,500 lbs. for 69 kV design, 4,440 lbs. for 15 and 25 kV design

Oil filling quantity 345 gals./2,590 lbs. for 69 kV design, 270 gals./2,025 lbs. for 15 and 25 kV design

Time per operation Approx. 2 seconds

Table 1 General data

1 Technical Data


1.2 Application Limits

The maximum allowable recovery voltage across the reversing switch during its operation is 20 kV.

Tie-in resistors are necessary in case 20 kV are exceeded.

Tap changer type RMV-II-1500-15

RMV-II-1500-25

RMV-II-1500

RMV-II-2000-15

RMV-II-2000-25

RMV-II-2000

RMV-II-2500

Operating voltage phase-to-phase and to ground

15 kV 26.4 kV 72.5 kV 15 kV 26.4 kV 72.5 kV 72.5 kV

Three phase kVA of regulation

36,000 kVA

36,000 kVA

72,000 kVA

48,000 kVA

48,000 kVA

96,000 kVA

120,000 kVA

LTC through-current 1,500 A 1,500 A 1,500 A 2,000 A 2,000 A 2,000 A 2,500 A

Tap-to-tap voltage 1,000 V 1,000 V 2,000 V 1,000 V 1,000 V 2,000 V 2,000 V

Impulse withstand vol-tage (full wave) phase-to-phase and to ground

125 kV 150 kV 400 kV 125 kV 150 kV 400 kV 400 kV

Power-frequency test voltage phase-to-phase and to ground

40 kV r.m.s.

50 kV r.m.s.

140 kV r.m.s.

40 kV r.m.s.

50 kV r.m.s.

140 kV r.m.s.

140 kV r.m.s.

Impulse withstand vol-tage (full wave) across tap range

75 kV 75 kV 250 kV 75 kV 75 kV 250 kV 250 kV

Power-frequency test voltage across tap range

26 kV r.m.s.

26 kV r.m.s.

70 kV r.m.s.

26 kV r.m.s.

26 kV r.m.s.

70 kV r.m.s.

70 kV r.m.s.

Impulse withstand vol-tage (full wave) tap-to-tap

45 kV 45 kV 125 kV 45 kV 45 kV 125 kV 125 kV

Power-frequency test voltage tap-to-tap

15 kV r.m.s.

15 kV r.m.s.

50 kV r.m.s.

15 kV r.m.s.

15 kV r.m.s.

50 kV r.m.s.

50 kV r.m.s.

Number of positions (standard)

33 33 33 33 33 33 33

Regulating winding sections

9 (8 effective)

9 (8 effective)

9 (8 effective)

9 (8 effective)

9 (8 effective)

9 (8 effective)

9 (8 effective)

Table 2 Application Limits

1 Technical Data


1.3 Equipment Standard Features

• Finish: light gray epoxy solid resin primer

• Oil gauge with low level SPDT contacts

• Provision for pressure relief device

• Drain valve, 1 in. globe with sampler

• Guide pins for access door

• Non-corrosive hardware

• Dehydrating breather

• Handcrank with interlocking switch

• Cam switch control: tap changer pilot shaft 10 cams, tap changer limit shaft 4 cams

• Position indicator: 16L-N-16R, 33 positions/32 steps

• Wiring: 12 pt. terminal blocks, PVC-insulated wire, preinsulated terminals

• Air compartment heater with thermostat

• Stainless steel access door studs

• Vacuum interrupters with monitoring system

• Drive motor: single-phase, 208 - 240 V, 60 Hz, 1,725 r.p.m. (standard, other available on request)

2 Safety instructions


2 Safety instructions

All personnel involved in installation, commissioning, operation, maintenance or repair of the equipment must:

• be suitably qualified

• strictly observe these Operating Instructions.

Improper operation or misuse can lead to

• a reduction in the efficiency of the equipment

• damage to the equipment

• serious or fatal injury to personnel.

Safety instructions in this manual are presented in three different forms to emphasize important information.

WARNING

This information indicates particular danger to life and health. Disregarding such a warning can lead to serious or fatal injury.

CAUTION

This information indicates particular danger to the equipment or other property of the user. Serious or fatal injury cannot be excluded.

These notes give important information on a certain subject.

The instructions contained in this manual apply for tap changers with standard position designation 16L...N...16R only. For LTC’s with a different position desi-gnation please refer to the LTC sequence chart supplied for each order.

Drawings and illustrations contained in this instruction manual are subject to change without notice and are for reference only. For specific details refer to drawings submitted with each individual customer order.

3 Description


3 Description

The RMV-II Load Tap Changer is used in conjunction with oil-immersed power transformers, regulators and phase shifting transformers to change taps under load thereby controlling voltage magnitude or phase angle, Figure 1.

The tap changer works on the preventive autotransformer (reactor) switching principle with vacuum interrupters to accomplish the tap change. Vacuum inter-rupters are used to interrupt the circuit within a half cycle. The interruption takes place in a vacuum of approximately 10-6 torr instead of the usual arcing under oil. Thus, oil contamination is eliminated.

Figure 1 Three-phase RMV-II load tap changer

3 Description


3.1 Design

The RMV-II load tap changer is a three-phase design with full insulation bet-ween phases and to ground, Figure 2.

It consists of an oil compartment containing tap and change-over selectors (reversing or coarse/fine), vacuum interrupters and by-pass switches, a sepa-rately housed drive mechanism/cam switch assembly and other accessories as required by customer specifications. Each phase consists of a tap and change-over selectors positioned on an epoxy molded terminal board and a vacuum interrupter and by-pass switch on a separate vertical insulating panel mounted rigidly from the top of the tap changer oil compartment. All switching elements involved in the tap change operation, selector and change-over selectors, vacuum interrupters and by-pass switches of all phases, are driven by one main shaft from the drive mechanism.

The vacuum interrupter drive assembly is a cam action spring driven mecha-nism which impacts an operating rod, when opening and closing. The operating rod is connected to the vacuum interrupter moving contact.

Figure 2 Tap changer oil compartment

3 Description


The vacuum interrupter consists of a stationary and a moving contact enclosed in a vacuum-tight ceramic insulating envelope, Figure 3.

The moving contact is sealed through a flexible metal bellows protected from the arc by a shield. A metal shield surrounds the contacts forming an arc cham-ber and condensing surface to collect vaporized contact material which arises during arcing.

The entire tap changer mechanism except the motor drive is housed in an oil-tight, flat finished steel tank which is designed to be welded onto the transformer main tank, Chapter 4.2.1. This tap changer oil compartment has a gasketed, hinged access/service door.

The motor drive/cam switch assembly is normally housed in a separate air com-partment and is accessible through a weather-proof hinged door. Optionally, the compartment can be mounted at a lower level.

Figure 3 Vacuum interrupter, schematic layout

3 Description


3.2 Operation

Figure 4 Typical RMV-II winding layout (LTC on position 16 L)

Figure 5 Tap change from position 16 L to 15 L

3 Description


The tap changer operation is divided into three major functions, Figure 4 and Figure 5:

1. Arc interruption and reclosing by use of the vacuum interrupters in con-junction with the associated by-pass switches.

2. Selection of the next tap position by the tap selector assemblies in proper sequence with the operation of the vacuum interrupters and by-pass switches.

3. Operation of reversing or coarse/fine selector in order to double the num-ber of tap positions.

The tap changer is operated by a motor drive mechanism which drives the main insulating drive shaft through a reduction gear. A bevel gear assembly drives the horizontal insulating drive shafts between selector switches.

The tap selector geneva gears, vacuum interrupter and by-pass switch assem-blies of each phase are driven through crossed helical gears to assure a precise operational sequence of the switching components.

When moving from one tap position to the next, one set of by-pass switch con-tacts opens, while the second set stays closed, routing the current through the vacuum interrupter just prior to its operation. The vacuum interrupter opens by a spring-operated mechanism before the tap selector moving contact selects the next tap. The vacuum interrupter then closes under spring force and locks in place followed by the by-pass switch reclosing to shunt the vacuum interrup-ter, thus completing the tap change operation.

The tap selector connects the preventive autotransformer alternately into a bridging or a non- bridging position. The change-over selector operates only when changing from position 1 L to N or N to 1 L.

3.3 Tap Selector

The tap selector consists of two contact arms operated alternately by geneva gears, Figure 6. The geneva gears also lock the movable contacts on position between operations.

The stationary contact bus bars are cast into the epoxy molded terminal board. They provide support for the double-deck stationary contacts.

3 Description


Each moving contact assembly consists of parallel contact fingers. The number of contact fingers used depends on the through-current ratings of the LTC. The stationary contacts and the inner collecting ring are silverplated. The moving contact assemblies are springloaded to provide safe contact force for both the normal load current and the excessive current during short-circuit conditions.

3.4 Change-over Selector (Reversing or Coarse/Fine)

The silverplated stationary contact assemblies of the change-over selector are mounted on bus bars cast into the epoxy terminal board adjacent to the tap selector assembly. The moving contact arm is operated by an insulating shaft and linked through a double-lever mechanism to the geneva gear assembly.

The change-over selector moving contact assembly is of the same design as the tap selector contacts but uses an increased number of parallel contact fin-gers.

Figure 6 Tap selector, by-pass switch and change-over selector, three-phase assembly

3 Description


3.5 Vacuum Interrupter

The vacuum interrupter assembly is mounted vertically on the front of the insu-lating panel, Figure 7. Vacuum filling is, therefore, not required when oil is repla-ced in the field. Cam action drives the vacuum interrupter through a spring mechanism which latches in at its end positions. The mechanism provides a direct drive by its operating rod to the vacuum interrupter contact, both moving in the same action line. The interrupter is locked in the open position while the selector switch changes taps. Upon completion of the tap selection the interrup-ter mechanism unlocks and the moving contact recloses under positive spring force. Opening and closing speeds of the vacuum interrupter are dashpot con-trolled.

Figure 7 Vacuum interrupter, single-phase assembly

3 Description


3.6 By-Pass Switch

The by-pass switch is located on the opposite (back) side of the insulating panel from the vacuum interrupter mechanism and is operated from the same drive shaft, Figure 8. It consists of two contact assemblies with parallel springloaded contact fingers that close on a silver-plated contact rod.

The moving contacts are cam operated to open and reclose. The by-pass switch normally bridges between the legs of the preventive autotransformer, thus by-passing the vacuum interrupter. During a switching operation the by-pass switch opens one set of contacts allowing current to be directed by the remaining closed set of contacts through the vacuum interrupter before it ope-rates.

Figure 8 By-pass switch, single-phase assembly

3 Description


3.7 Monitoring System

A unique monitoring system is utilized to protect the LTC in the unlikely event that a vacuum interrupter fails to interrupt and transfer the load current during a tap change operation, Figure 9.

WARNING

Do not operate the LTC without this monitoring system properly connected and functional if the transformer is energized. Follow the test procedures outlined in Chapter 4.4.3.

During operation, if the monitoring system trips, do not reset until the LTC has been inspected and the cause of the trouble corrected.

Failure to adhere to these requirements can lead to property damage and/or personal injury.

Please contact Reinhausen Manufacturing for assistance and refer to Chapter 8 for further details.

Figure 9 Monitoring system schematic diagram

3 Description


Three saturating current transformers in the stationary contact leads of the vacuum interrupters are provided. The electrical signal from the current trans-former is transmitted by fibre optic cable to the monitoring circuit board. These cables must be handled with reasonable care. DO NOT BEND OR COIL these cables to a radius smaller than 100 mm (3.94”). Overbending will damage the cable and destroy its ability to carry a light pulse.

The system monitors the current in all three phases at a threshold of less than 20 amperes after the interrupters are open but prior to the movement of the tap selector contacts. The logic circuit evaluates these signals and protects the LTC in case of vacuum interrupter failure by operating a bistable output relay. This relay operation returns the LTC to the original position before the tap selector opens the circuit and prevents further operations.

The monitoring system’s control and indicating components are located inside the door of the drive mechanism cabinet. It contains the electronic circuitry, power supply, 86 L, 86 C and 86 R trip relays, SP supervision power relay, 3 red and 3 yellow LEDs and a green LED, a TEST push-button (green) and a RESET push-button (red).

The red LEDs indicate energizing of the associated trip relays. The yellow LED’s indicate energizing of the SP relay denoting loss of CT signal for the associated phase. The green LED indicates operability of the system. The green TEST push-button is used to test the internal circuitry of the monitoring system.

Pressing the TEST push-button simulates a failure condition of all three phases, energizes the trip relays and lights the three red LEDs. After testing the monito-ring system must be reactivated by pressing the red RESET push-button.

CAUTION

The monitoring system is functional only when the RMV-II load tap changer is operated by control power (either by manual control switch raise/ lower or automatically). It does not function if the unit is operated by hand cranking. Therefore, never hand crank the unit if the transformer is energized as damage to the transformer and/or personal injury may result if any of the vacuum interrupters fails to interrupt.

An optional mechanical interlock is available to prevent hand cranking if a vacuum interrupter failure occurs or upon loss of control power. As with any safety device, the mechanical interlock should not be intentionally defeated or tampered with.

3 Description


The system should be tested at installation and scheduled examination inter-vals. The physical layout of the monitoring system circuit board is shown in Chapter 4.4.3, Figure 11.

3.8 Drive Mechanism/Cam Switch Assembly

The drive mechanism and cam switch control assembly are housed in a sepa-rate air compartment attached to the bottom of the tap changer oil compartment, Figure 10. The entire assembly, together with the position indicator, motor capacitors and terminal blocks, is mounted to a detachable mounting plate affixed to the rear wall of the motor drive housing.

The drive mechanism is powered by a single-phase, 208 - 240 volt, 60 Hertz, permanent split capacitor motor which is flange-mounted to a self-contained reduction gear unit. This gear unit is grease filled and sealed at the factory to eliminate the need for subsequent lubrication. Its output shaft couples directly to the tap changer main shaft which extends through the tap changer oil com-partment bottom. An auxiliary reduction gear driven from this gear unit operates the factory preset cams and the position indicator.

The air compartment is accessible through a front mounted, weather-proof, hin-ged door. The LTC tap position indicator is visible through a viewing port in the door.

The position indicator has two red drag hands indicating the maximum and mini-mum positions (raise and lower) of the actual operating range.

Figure 10 Drive mechanism cam switch assembly, hinged door open showing monitoring system and handcrank

3 Description


A handcrank coupling with interlocking switch is provided at the main gear unit and can be used with the air compartment door open.

A modified version of the drive mechanism/cam switch assembly with weather-proof drive shaft seal on top of the housing allows for separate attachment of the air compartment to the transformer main tank at a lower level, if required. In this case, a single drive shaft couples tap changer and drive mechanism. Its length may be varied according to customer specifications (max. shaft length 2,500 mm (98.4 in.).

The drive mechanism requires a separate customer supplied control cabinet with appropriately sized motor control relays and protective circuit breaker. On request this control cabinet can be supplied by Reinhausen. Please consult wiring diagram supplied with each order for specification guidelines concerning motor control relays and protective circuit breaker.

3.8.1 Option

The drive mechanism assembled on the mounting plate including cam switch assembly, monitoring system circuit board, position indicator, drive shaft and required fittings is also available to be mounted into the transformer control cabinet by the customer.

4 Installation


4 Installation

4.1 Receiving, Handling and Storage

Before mounting on the transformer the tap changer oil compartment and the drive mechanism air compartment should be opened and inspected for damage which may have occurred in shipment due to rough handling. If shipping damage is evident, file a claim with the transporting company. The sales office of Reinhausen Manufacturing should be notified promptly of damage occurring during shipment from its plant.

No special handling of the tap changer is required other than that accorded the transformer in general.

The tap changer is shipped from Reinhausen Manufacturing filled with dry nit-rogen under positive pressure. If the tap changer is opened and the nitrogen fill is lost the tap changer oil compartment must be purged and filled with dry nitro-gen at a pressure not exceeding 4 psi, when stored again indoors.

The LTC and drive mechanism are not prepared for storage in an unheated buil-ding or outdoors. Such conditions require:

• filling the LTC tank with clean, dry oil and the gas space with dry nitrogen,

• weather protecting of the exterior of the tank and terminal board,

• heating the drive mechanism air compartment by connecting the built-in space heater to power.

4 Installation


4.2 Mechanical Set-up

4.2.1 Attaching the Oil Compartment

Check the size of the opening in the transformer main tank. For minimum tank opening dimensions see customer dimensional arrangement drawing. Weld the LTC compartment to the transformer main tank taking care that the weld is oil-tight, pressure and vacuum resistant.

4.2.2 Mounting the Drive Mechanism Air Compartment

The LTC and motor drive are shipped on separate pallets in the neutral position. The LTC and motor drive serial numbers should be checked prior to assembly to ensure they match.

Prior to shipment the LTC is locked in the neutral position by a cotter pin which is inserted through the boss and the drive shaft extension on the bottom of the tank. This cotter pin should not be removed until the motor drive is ready for assembly to the LTC.

WARNING

Welding adjacent to the epoxy terminal board may distort its mounting surface and cause damage to the terminal board or its oil seal.

The transformer manufacturer is responsible for mounting the LTC on a trans-former tank wall that is designed to withstand normal test and operating pres-sures (15 psi maximum). A 0.25-in. oil tight weld is required around the outside perimeter of the LTC mounting flange. Welding on the transformer side of the LTC is not required.

WARNING

Do not turn the LTC input shaft nor the drive mechanism output shaft until they are coupled with each other. Coupling LTC and motor drive in non-matching positions may cause mechanical damage.

4 Installation


The motor drive unit is also shipped in the neutral position. Confirm this by che-cking that:

1. the position indicator is on neutral

2. the cam switch timing wheel is at zero degrees

4.2.2.1 Standard Mounting (Attachment to the LTC oil compartment)

The LTC and motor drive must be coupled in the neutral position per drawing 4D32012 (see appendix).

4.2.2.2 Detached (Ground Level) Mounting (Attachment to the transformer main tank)

This version requires, provided by the transformer manufacturer, a mounting support on the transformer main tank. The support is fastened to the rear of the drive mechanism housing.

The LTC and motor drive must be coupled in the neutral position per drawing 4D32009 (see appendix).

4.3 Electrical Connections

4.3.1 Connecting the Tap Leads to the LTC

Connect tap leads to the proper LTC terminal on the epoxy terminal board. For terminal location and designation see dimensional arrangement drawing.

4.3.2 Connecting the Monitoring System and the Drive Mechanism

The drive mechanism is to be wired according to the wiring diagram which is supplied with each order. To connect the monitoring system, insert the cable plug from the motordrive cabinet into the receptacle on the bottom of the LTC tank per drawing 4D32012 (see appendix).

4 Installation


4.4 Test Procedures

4.4.1 Manual Test Procedures

Open the LTC compartment and the drive mechanism. Insert the handcrank into the guide lever and engage the motor drive. Sequence check the LTC operation by hand cranking one step in the lower direction, position N to 1L, see sequence chart in drawing 897 151 of appendix, Chapter 10.5. This movement requires 7.5 handcrank revolutions.

While hand cranking from N to 1L (counter-clockwise) observe that the by-pass switch P2 opens, then the vacuum interrupter trips open and the tap selector moving contact P1 (nearest to the terminal board) moves from M to 11. At the same time as the tap selector, the changeover selector will move from B to A. Continue cranking and the vacuum interrupter will reclose and finally the bypass switch P2 closes, positioning the tap changer in “on position”.

Hand crank in the raise direction (clockwise) back to neutral (position N). The same events should take place in the same order as above except that the movement is from 11 to M and from A to B.

Then check the LTC operation by hand cranking from position N to 1R. While hand cranking in the raise direction (clockwise) observe that the by-pass switch P3 opens, then the vacuum interrupter trips open, followed by the tap selector moving contact P4 (furthest from the terminal board) moving from M to 4. Continue hand cranking and the vacuum interrupter will reclose, then the by-pass switch P3 will reclose, positioning the LTC in “on position”.

Hand crank in the lower direction (counter-clockwise) back to neutral (position N). The same events should take place in the same order as above except that the movement is from 4 to M.

Withdraw the handcrank and place it in the storage holder provided.

Observe the engagement of selector switch and reversing switch moving con-tacts for smooth, non-binding operation. Observe closure of bypass switch.

Observe the engagement of tap selector moving contacts for smooth, non-binding operation.

Observe closure of by-pass switch.

4 Installation


4.4.2 Motorized Test Operations

Operate the tap changer with the drive mechanism connected to electrical power. Do not run more than 120 consecutive operations or damage to the motor may occur.

Make sure that both the monitoring system and the drive mechanism are con-nected to power. Make sure that the motor control breaker is closed and the handcrank is in its storage holder. Place the monitoring system into “Mainte-nance Mode” as per Chapter 8.1 of this manual. Operate the LTC by closing the raise/ lower switch one step from neutral position toward the lower limit. Check the movement of the position indicator to confirm that the motor is con-nected properly. The drive mechanism should operate and stop “on position”.

Operate the LTC one step of at a time from position 1L toward the lower limit.

Open the handcrank interlock switch by lifting the handcrank guide lever while operating the LTC. The tap changer should not operate. Continue with the ope-ration toward the lower limit. Stop on the lowest limit position (position 16L). With one hand on the motor control breaker, close the raise/lower switch in the lower direction. The drive mechanism should not run. If it does, turn off the cir-cuit breaker at once because either the limit switch timing or connections are wrong.

Remove the handcrank from its storage holder and insert. Try to hand crank the tap changer in lower direction. The mechanical stop should operate in approxi-mately 2.5 handcrank revolutions. This can be felt readily on the handcrank. Do not force the handcrank.

Run the tap changer one step at a time in the raise direction and repeat the checks as above in the raise limit (position 16R). 0.5 handcrank revolutions in the raise direction should engage the mechanical stop.

Upon completion of the checks return the tap changer to the assembly position (position N), return the handcrank to its storage holder. Close the drive mecha-nism air compartment.

Extended operation of the LTC without oil in air is not recommended. However, the LTC may be run once to both limits and back to neutral position for test pur-poses. When running the LTC electrically it typically stops between 0° to 18° on the timing wheel. This is a normal condition.

4 Installation


4.4.3 Monitoring System Tests

Open the drive mechanism door for access to the monitoring system. There is a green LED which indicates operability of the system. Two push-buttons are provided, one red to reset and one green to test. Figure 11 shows the layout of these items.

Check the green LED to ensure that the monitoring system is operative.

4.4.3.1 Power-off Test at the Transformer Control Cabinet

Open the transformer control cabinet. The green lamp 86 GL in the control cabi-net should be on indicating that the monitoring system is energized.

Drop control power. Remove cover from monitoring system circuit board. Inter-rupt the power supply to the circuit board by removing the 0.25 A fuse. Reinstate control power. The 86 GL lamp should then be off and the red lamp 86 RL, on. Try to operate the LTC drive mechanism. It should not start. Reinstall the moni-toring system fuse and it’s cover. Close the transformer control cabinet.

CAUTION

The monitoring system is functional only when the RMV-II load tap changer is operated by control power (either by manual control switch raise/ lower or automatically). It does not function if the unit is operated by hand cranking. Therefore, never hand crank the unit if the transformer is energized as damage to the transformer and/or injury to the operator may result if any of the vacuum interrupters fails to interrupt.

4 Installation


4.4.3.2 Operational Tripping Test

Connect a variable CT to busbar P2 and the stationary contact A of one of the vacuum interrupter assemblies, Figure 20, for example left phase. The CT should be able to drive a current of at least 20 Amperes.

A monitoring system trip test set is available; reference spare parts list in Chap-ter 9 of this manual.

Place monitoring system into “Maintenance Mode” so that all three yellow LED’s are flashing slowly, Chapter 8.1. Raise the CT input voltage to drive a primary current of approximately 20 A. Start the drive mechanism in one direction. The 86 L relay should trip, the associated red LED should light, the drive mechanism should stop and return to its previous position. The moving selector contact must not disconnect from the stationary during the process. The drive mecha-nism must not be operable in either direction, until the monitoring system is reset.

Perform same test procedure with the vacuum interrupter assemblies of center and right phase. Observe tripping of 86 C and 86 R relays. Be sure to reset the monitoring system so that all 86 relays are untripped and all red lights out. Close the LTC compartment access door.

Figure 11 Monitoring system. cover removed

Green LED

Green push button=TESTRed push button=RESET

3 red and 3 yellow LEDsRight, Center, Left

Do not overtighten the LTC access door nuts. These nuts should be tightened to a maximum torque of 15 Nm (11.1 ft. lbs.), which corresponds to a compres-sion of the gasket to 5/16” thickness.

4 Installation


4.5 Oil Filling/Transformer Vacuum Processing

In preparation for factory testing of the transformer at the maximum tap changer voltage rating (15 kV, 25 kV or 69 kV), vacuum fill the LTC tank with oil to the proper level prior to initiating any transformer tests.

1. Make the oil input and vacuum connections to the compartment. Remove and plug the 1/4-in. coupling to the dehydrating breather system.

2. Hold a vacuum of 1 torr, or better, on the tap changer compartment for 2 hours prior to filling. Continue to hold this vacuum during filling. Degassed oil will facilitate this process.

3. Break the vacuum with dry, inert gas.

4. Take three oil samples from the LTC oil compartment and test for breakdown voltage. All three samples should have a minimum breakdown voltage of 30 kV by ASTM D 877 or 28 kV by ASTM D 1816. Moisture content should not exceed 20 ppm by ASTM D1533.

5. Run the tap changer with motor power through the complete range limit-to-limit, 16 L to 16 R.

6. Reclose the compartment openings.

During transformer vacuum processing (drying) the LTC should be considered part of the transformer. Therefore, the tap changer and transformer gas spaces should be connected together through the vent plug. The differential pressure across the terminal board and its gasket system will then be zero during the entire processing cycle. Auxiliary devices, e.g. dehydrating breather, sudden pressure relay, etc., must be removed or disconnected during processing or filling to prevent damage due to oil “flooding”. The sudden pressure relay can also be damaged by rapid pressure changes (consult the instruction leaflet). The vacuum should always be broken with dry, inert gas to prevent moisture contamination.

The RMV-II tank is designed to withstand a full vacuum. The terminal board is designed to withstand a maximum differential pressure of 18 psi. This allows for full vacuum in the LTC tank with a maximum positive pressure of 3.3 psi from the transformer side of the terminal board.

5 Maintenance-Free Schedules and Service



Prior to initial energization of the transformer, perform tests and examinations per Chapter 4.4.3 and 5.4.1.

Because of its basic design, the RMV-II Load Tap Changer will require a mini-mum of maintenance. However, as with any mechanical device, it should receive periodic examination.

5.1 Maintenance-Free Intervals

The RMV-II is a Maintenance-Free Load Tap Changer through 500,000 opera-tion count intervals or through 7 year time spans, whichever occurs first.

The Maintenance-Free interval can become strictly operation count based regardless of time span by use of the Model 'B' monitoring system. Refer to Chapter 8 for detailed information.

The Maintenance-Free intervals, whether time-based or operations count-based, will only need complementing by checks (annually) as follows:

Routine site visits should include as good practice the following:

Test Check Reference

Oil Sampling Check for dielectric, combusti-ble gases and water content

Chapter 4.5

VIM System Test Check circuit board ‘test & reset’ function; simulated monitoring runback & ‘power off’ test

Chapter 8.4, 4.4.3

Motor drive condition Check heater & accessory operation; general mechanical condition

Chapter 4.4.2

Table 3 Annual checks

Test Check Reference

Dehydrating Breather check

Check for oil level and desiccant material color

Chapter 7.3, 7.4

Check for oil leaks All areas with seals or gaskets that retain oil should be exami-ned.

Table 4 Routine checks



5.2 Taking the LTC out of Service

1. De-energize the transformer and ground all external bushings.

2. Open the drive mechanism motor control breaker.

3. Record the number of operations shown on the tap changer operations counter.

5.3 Draining the Oil

1. Take a tap changer oil sample.

2. Test and record the breakdown voltage.

3. Remove the vent plug on top of the LTC compartment and drain oil.

If the drained oil is to be reused it should be pumped through a filter press to remove the small amount of carbon and metallic particles produced by the switching duty of the by-pass switch and the normal wear of the mechanism. Oil should be stored in clean, dry containers if reused.

Open the LTC access door. Check the door gasket for signs of deterioration. Replace with a new gasket if necessary.

CAUTION

Transformer oil should always be handled as a flammable liquid. LTC tanks may, under some conditions, accumulate explosive gasses.

Filtering and handling the oil may generate static electricity. A damaging explosion could result if any electrical discharge takes place in an explosive gas mixture. Safety precautions should include purging the gas space with dry nitrogen before filtering and grounding the transformer, its bushings, and all oil handling equipment.



5.4 Internal Examination

1. Check the LTC compartment floor and horizontal surfaces for debris that might indicate abnormal wear or trouble developing.

2. Check all sliding surfaces for signs of excessive wear.

3. Make a general examination of the tightness of bolts and nuts on those parts which are subject to mechanical shock and vibrations during tap change operation.

5.4.1 Vacuum Interrupter Examination

Check the condition of the flexible connector for broken strands.

5.4.1.1 Mechanical Test

With the tap changer in “on position” lift the connector on the moving contact by means of a large screwdriver and pull the contact open about 6 mm, Figure 12.

Let it snap close. A good vacuum interrupter will require an opening force of approx. 35 to 40 pounds. The moving contact should close freely and impact with a short metallic ring.

If an interrupter were completely full of oil, due to bellows failure, it would not flash over on the hi-pot test but the pull to separate the contacts would not be more than 5 to 10 pounds or the contact would not snap close quickly.

CAUTION

The monitoring system uses FIBRE OPTIC CABLES inside the LTC to transmit signals to the electronic control box. These cables must be handled with reasonable care. DO NOT BEND OR COIL these cables to a radius smaller than 100 mm (3.94-in.). Overbending will damage the cable and destroy its ability to carry a light pulse.



5.4.1.2 Contact Erosion Indicator

A contact erosion indicator consisting of a stationary pointer and movable scale is provided. This indicator is located behind a viewing port of the drive mecha-nism cover plate, Figure 13. A scale showing the start (S) and the finish (F) points is engraved. This scale is a visual indication which gives a rough estimate

Figure 12 Mechanical test procedure for good vacuum

The vacuum interrupter is rated for one million operations at full load. (Over-load conditions may reduce the operational life of the vacuum interrupter). However, when the erosion indicator is near the F (finish) line of the index, turn the handcrank slightly until the upper pawl can latch in. The vacuum interrupter has to be replaced when the gap between the operating rod bolt and drive dog of the drift-off plate is smaller than 0.5 mm (Figure 32 and Figure 33 show a gap of 5.3 mm when the vacuum interrupter is in the new condition).



of contact wear. The anvil gap, Figure 32 and Figure 33, is the governing factor for worn vacuum interrupter replacement. Recording the anvil gap at receipt and subsequent maintenance intervals will provide the best estimate of remai-ning contact life.

At installation the indicator should be checked to confirm that the pointer is on the S (start) line.

When the load tap changer is opened for the first time and at subsequent exa-minations (see Chapter 5.1) the indicator should be checked so that contact wear can be evaluated. By observing the position of the pointer on the scale and the number of actual tap changer operations, a rough estimate of the remaining life can be made.

Figure 13 Vacuum interrupter contact erosion indicator



5.4.1.3 Hi-Pot Test

With the tap changer “off position” (180° on the cam switch timing wheel) test each vacuum interrupter by applying a hi-pot test of 25 kilovolts AC or 30 kilovolts DC for one minute as follows:

1. Ground all transformer windings.

2. Ground bus bars P2 and P3 (see Figure 14 and Figure 16).

3. Temporarily remove the solid bus bar connector, Figure 14, to the vacuum interrupter stationary contact (bottom side).

4. This will also require disconnecting the fibre optic cable from the satura-ting current transformer.

Due to the high reliability we have experienced with our products over many years in service, we recommend the Hi-Pot Test only as a means of trouble-shooting in the unlikely event of a specific suspicion that a vacuum interrupter might be defective.

Figure 14 Location of P2 & P3, solid bus bar connector removed

Note the insulating panel between vacuum interrupter and support

P3 P2



Be sure to note the color code and location of the leads for reinstallation (the green lead is closest to the CT, the blue lead is in the center, and the orange lead is farthest from the CT). Attach the fiber optic cable to the panel support at the top of the tank prior to performing the hipot test.

Locate an insulating panel 6.25 in. x 6.25 in. x 0.125 in. between vacuum inter-rupter and support, Figure 14.

5. Perform the hi-pot test using one of the listed test circuits as described and referenced in Figure 15.

6. Reattach the bus bar shunt connector(s). Use new lock nuts M6 (see hi-pot Spare Parts Kits RM Part No. 095792, Chapter 9), max. torque 9.5 Nm (71 in. lbs.). Remove the insulating panel. Attach the fibre optic cable. Operate the tap changer to “on position”. Remove the grounds.

A - Testing with an asymmetrical test transformer, Figure 15 A

(A test set with one hot lead and one ground lead)

Connect the ground test lead to the vacuum interrupter moving contact (top) and the hot test lead to the stationary contact (bottom). Perform the hi-pot test.

B - Testing with a symmetrical centertapped test transformer, Figure 15 B

(A test set with two hot leads and with max. test voltage of 50 kV or higher)

Connect the ground test lead to the vacuum interrupter moving contact (top) and the hot test lead to the stationary contact (bottom). Perform the hi-pot test.

C - Testing with a symmetrical centertapped test transformer, Figure 15 C

(A test set with two hot leads and with max. test voltage lower than 50 kV)

Special method if the maximum voltage of the test transformer is less than 50 kV.

The vacuum interrupter must be free of surface films and clean before hi-pot or a false failure result may be achieved.



CAUTION

Before performing this hi-pot test (C) the flexible connector assy. 094807 must be disconnected. Push back the screws on the vacuum interrupter moving contact.

Connect the ground test lead to P2 and P3, Figure 16. Connect one hot test lead to the vacuum interrupter moving contact (top) and the other hot test lead to the stationary contact (bottom).



Figure 15 Test circuits to be used for the Hi-Pot Test

A Test transformer without center tap

B Test transformer with grounded center tap and with max. test voltage of 50 kV or higher

C Test transformer with grounded center tap, max. test voltage lower than 50 kV



A vacuum Interupter Hi-Pot Test Set is available; reference spare parts list in Chapter 9 of this manual.

Figure 16 Location of P2 & P3 busbars, solid and flexible bus bar connectors removed

Note the insulating panel between vacuum interrupter and support

P3 P2



5.4.2 By-pass switch

Check the condition of the by-pass switch contacts P2 and P3, Figure 17. These contacts see light arcing as they switch the tap changer current through the vacuum interrupter during a tap change operation. Therefore arcing tips are provided which separate shortly after the moving finger contact assembly opens. Normally, the life of these contacts will by far exceed the vacuum inter-rupter life.

Figure 17 By-pass switch, single-phase assembly, location of P2 & P3 bus bars

Figure 18 Measuring the by-pass switch arcing tip thickness

P3 P2



With the moving contact finger assembly closed measure the total thickness of both arcing tips, Figure 18. The thickness should not be less than 10.5 mm when eroded.

5.5 Preparing the LTC for Service

Perform vacuum interrupter examination as per Chapter 5.4.1.1.

Wipe the LTC compartment down to remove all dirty oil, carbon deposits, metal-lic fall-out and moisture that may have condensed, during the open time, on the walls and insulating surfaces.

Check that drive mechanism and monitoring system are operating properly. Perform test operations of the drive mechanism and a monitoring system test according to Chapter 4.4.

Close the LTC compartment.

Make the oil input connections to the LTC drain valve. Remove and plug the 1/4-in. coupling to the dehydrating breather system.

Fill the LTC compartment with clean, dry oil through a filter press to the proper level. Vacuum filling is not required during field service.

After oil filling reclose the LTC compartment openings and reconnect the dehy-drating breather system.

Run the Tap Changer with motor power from the neutral (or assembly position) to position 16L (or the lowest position) for approximately 100 operations without pausing. Return to the neutral position.

Let the tap changer sit de-energized for one hour to allow gas bubbles to dissi-pate from the oil.

Take three oil samples and test for break-down voltage. All three should have a minimum breakdown voltage of 30 kV by ASTM D877 or 28 kV by ASTM D1816. Moisture content should not exceed 20 ppm by ASTM D1533.

A replacement of the stationary arcing contact tip becomes necessary when the total thickness of both arcing tips is 10.5 mm or less.

Do not overtighten the LTC access door nuts. These nuts should be tightened to a maximum torque of 15 Nm (11. 1 ft. lbs), which corresponds to a compres-sion of the gasket to 5/16" thickness.



The dehydrating breather should be checked to confirm that the desiccant is dry and the oil level in the clear plastic oil collection cell is between the two fill level lines on the cell, Figure 19.

Remove grounds from external bushings.

Figure 19 Dehydrating breather

Flare nut 3/8"

BracketPad(on transformer wall)

Protective grate

Oil Collection Cell

6 Replacement of the Vacuum Interrupter



6.1 Removing the Old Vacuum Interrupter Assembly

When removing the old vacuum interrupter carefully observe the configuration of the parts and hardware during disassembly so that reinstallation can be made easily and correctly. To remove the old vacuum interrupter proceed as indicated below, Figure 20.

CAUTION

The Fibre Optic Cables must be handled with reasonable care. DO NOT BEND OR COIL these cables to a radius smaller than 100 mm (3.94-in.).

Overbending will damage the cable and destroy its ability to carry a light pulse.

If removal of the vacuum interrupter is for any reason other than replacement, the anvil gap measurement, see Chapter 6.2, must be taken for reinstallation and proper setting of the vacuum interrupter erosion indicator.



1. Disconnect the fiber optic cable connecting to the CT located to the right hand side of the vacuum interrupter being replaced. Be sure to note the color code and location of the leads for reinstallation (the green lead is closest to the CT, the blue lead is in the center and the orange lead is far-thest from the CT).

2. Remove the CT using a 10 mm socket and wrench for the M6 mounting hardware, Figure 21.

Figure 20 Vacuum interrupter assembly

P3 P2

A



Figure 21 Removing the CT from the interrupter assembly



3. Loosen the hex jam nut M12 on the operating rod-bolt using a 19 mm wrench to turn the nut and a 28 mm wrench to hold the vacuum interrupter moving contact stem, Figure 22.

CAUTION

If the vacuum interrupter is being removed for reasons other than replacement DO NOT TWIST the moving contact.

This may damage the bellows and cause the vacuum interrupter to fail.

Figure 22 Loosen the lock hex nut on the operating rod bolt while holding the moving contact stem



4. Remove the M12 hex bolt from the stationary contact stem using a 19 mm wrench to turn the bolt and a 24 mm wrench to hold the vacuum interrupter contact stem, Figure 23.

Figure 23 Use a 19 mm wrench to turn the bolt and a 24 mm wrench to hold the vacuum interrupter contact stem



5. Unscrew the clamp on top of the vacuum interrupter, which holds the interrupter to the bracket. Using a 7 mm socket remove the clamp completely, Figure 24.

6. Remove brass support L-bracket by bending back locking tabs. Loosen the four M8 nuts using a 13 mm wrench, Figure 25. While holding the bracket, slide the four M8 bolts out to drop the bracket down, Figure 26.

Figure 24 Unscrew the clamp on top of the vacuum interrupter

Note: Replace locking tabs with new ones during reassembly.



7. Unscrew the vacuum interrupter completely by turning it off from the operating rod, Figure 27. Make sure to retain the Belleville washer under the hex jam nut in place for reinstallation. Do not change the position of the cam disk by hand cranking the LTC.

Figure 25 Remove the clamp completely Figure 26 Drop bracket down

Figure 27 Unscrew the vacuum interrupter completely



6.2 Installing the New Vacuum Interrupter

To install the new vacuum interrupter follow the steps previously described but in reverse order.

1. Locate the operating rod bolt and slip on the Belleville washer (concave side down) and the bus bar connector with flexible shunts under the hex jam nut. Thread the vacuum interrupter moving contact stem by hand on to the operating rod bolt until the hex jam nut M12 is reached, Figure 28. Do not tighten yet.

Lock tabs and lock nuts should not be used twice for reasons of reliability. Always use new lock tabs and lock nuts when reassembling the unit. Sufficient spare tabs and nuts are contained in our Spare Parts Kits, Chapter 9.

Figure 28 Screw by hand until the lock nut is reached



2. Reinstall brass support L-bracket with the four M8 bolts and nuts using new locking tabs. Be sure to orientate the hardware properly (flat ends of the bolt heads and nuts) to allow bending of the locking tabs on to the hardware, Figure 29. Attach the vacuum interrupter stationary contact stem (bottom end) to the solid bus bar connector using the M12 hex bolt and a M12 lock washer.

If a lock tab was originally used, replace it with the 19 mm lock washer supplied with the vacuum interrupter kit, refer to Chapter 10.9.

Tighten slightly but do not lock yet.

Figure 29 Bolt heads and nuts are aligned to bend locking tabs



3. Reinstall the clamp on top of the vacuum interrupter. Do not tighten firmly yet, Figure 30.

4. Turn the handcrank slightly until the upper pawl (latch-rod) can latch onto the by-pass drive mechanism. You can identify this action by viewing the sight hole in the upper right corner of the by-pass cover plate, Figure 31.

Figure 30 Reinstall clamp but do not tighten firmly yet

If reinstalling a used vacuum interrupter, use the previously measured value to adjust the interrupter. Chapter 6.1.



5. Insert a feeler gauge from the left side into the oval opening formed by the operating rod bolt (window) and the drive dog of the drift-off plate, Figure 32, Figure 33. The feeler gauge is to be set to 5.3 mm thickness.

Figure 31 Viewing the sight hole in the upper right hand corner

Figure 32 Location for feeler gauge measurement between operating rod bolt (window) and drive dog of driftoff plate (anvil gap)

5.3 mm



6. Turn the vacuum interrupter and thread it until the feeler gauge measures firmly. Check the position of the feeler gauge through the viewing port while turning, Figure 34.

Figure 33 Anvil gap measurement, schematic representation



Figure 34 Adjustment of vacuum interrupter to the operating rod-bolt during feeler gauge measurement.



7. Tighten the clamp to a torque of 2.5 Nm (22 in. lbs.). Hold the moving contact stem with a 24 mm wrench and tighten the hex head bolt M12 using a 19 mm wrench to a maximum torque of 30 Nm ( 22.1 ft. lbs.). Tighten the vacuum interrupter stationary contact stem with a 19 mm wrench, maximum torque of 45 Nm (33 ft. lbs.).

8. Perform several test operations between two tap positions to ensure the correct stroke of the vacuum interrupter moving contact. Perform the operations by hand cranking and observe the vacuum interrupter opening and closing. Finally set the load tap changer to "on position".

9. Check to ensure all locking tabs are bent in place and all hardware is tight and properly torqued.

CAUTION

Although a guide with parallel flats is provided for the moving contact stem, we recommend to avoid excessive twisting of the bellows which is attached to it. Excessive twisting will reduce the mechanical life of the bellows or will fracture the bellows, which destroys the vacuum making the vacuum interrupter inoperative.

Refer to Chapter 4.4 and Chapter 5.5 for testing requirements prior to placing the LTC back in service.

7 Dehydrating Breather Assembly



The dehydrating breather is designed to remove moisture from the air breathed into the load tap changer. It consists of a cylindrical glass body, top connecting flange, bottom breather/trap and an exterior protective grate with three obser-vation ports.

7.1 Receiving

The breather is shipped detail with the dehydrating material placed in separate containers.

7.2 Installation

(For dimensional and general installation details see drawing DD10008 in the appendix).

To mount the disassembled breather:

1. Fill the breather chamber with dry dehydrating material (approx. 2.2 lbs.) through the opening in the flange on the breather top.

2. Place the flange gasket on top of the flange followed by the mounting bracket, aligning the threaded hole with the flange opening. Secure with two M10 x 35 hex head bolts, washers and locking nuts.

Mount the dehydrating chamber to the pad (provided by the user) on the transformer tank wall. See sketch "A" on drawing DD10008 for recom-mended mounting pad dimensions. Secure with two M10 x 35 hex bolts, washers and locking nuts.

Connect the tubing between the top of the breather and one of the 0.25" half couplings provided on the LTC side walls.

3. Remove the clear plastic oil collection cell by squeezing the retaining bracket. Fill it with clean transformer oil until the oil level is between the two fill level lines on the cell. Carefully place the filled oil collection cell back onto the breather housing bottom.

All connections must be air tight. Use of a high temperature grease on the screw joints helps prevent rust and permits the parts to be removed easily when necessary.



7.3 Operation

The breather permits in- and out-breathing when there is a difference in pres-sure between the LTC gas space and the atmosphere exceeding the head of oil in the breather/trap. The dehydrating material is protected from the ambient humidity by the oil in the collection cell which also serves to trap any particles in the air during in-breathing.

The cylindrical body is filled with dehydrating material which is orange in color when in the dry state. When it becomes saturated with moisture, its color chan-ges to green or colorless. The color change can be observed through the obser-vation ports in the protective grate. The dehydrating material should be repla-ced when 75% of the material has changed from orange to green or colorless.

7.4 Maintenance

The time between subsequent changes of the dehydrating material depends upon the load cycle of the transformer and the ambient conditions. It is advisable to check the color of the material frequently at first, to determine the approximate time interval for replacement of the desiccant for the particular application.

A recommended method is to have a second charge of dry dehydrating material on hand in a sealed container. This allows a quick renewal of the dehydrating breather filling. The removed saturated desiccant can later be dried out and stored for the next change.

To replace the desiccant, carefully remove and empty the oil collection cell and remove the dehydrating breather from its holder by loosening the two M10 x 35 hex bolts. Empty the saturated material through the hole in the top flange into a pan. Refill the breather with a fresh charge and fill the oil collection cell with clean transformer oil to the level indicated on the cell. Reinstall the breather on its holder, making sure the flange gasket is in place. Finally, place the oil collec-tion cell in its bracket.

Two dehydrating materials (desiccant) are available:

1. Silica gel (6 to 16 mesh) which is orange in color when in dry state. It turns green when saturated.

2. Sorbead® ORANGE (4 to 8 mesh) which is orange in color when in dry state. It turns colorless when saturated.



The saturated desiccant can be placed in an open pan and dried at a tempera-ture of 130°C to 160°C (266°F to 320°F) for about 2- 3 hours. When dry, the material regains its orange color. Since the particles dry from the outside towards the center, the outer surface will change its color first. This initial change in color should not be considered as a complete reactivation of the desiccant. It should be allowed to dry as specified above.

8 Vacuum Interrupter Monitoring (VIM) System



8.1 Vacuum Interrupter Monitoring System Description

The RMV LTC utilizes a unique monitoring system to abort the tap change ope-ration in case a vacuum interrupter has failed to interrupt the current just prior to the opening of the tap selector contacts or in the event of monitoring system supply power loss. The system is the only one of its kind on a load tap changer.

Utilizing bias resistant fiber optic signals, which move through the LTC tank for a portion of each tap change, the RMV provides self-examination of each and every operation. Special DC logic within the monitoring system electronics inter-prets current sensing optical signals as trigger input is received from a precisely timed cam-operated microswitch (186). Should current be flowing through the vacuum interrupter circuit when it normally would be open, the LTC is immedi-ately stopped and returned to the position from whence it came. Latching alarm relays prevent further operation until the system has been reset. System verifi-cation must always take place prior to resetting and placing the LTC back in operation.

Specific components utilized in the monitoring scheme are as follows:

SP supervisory power indication relay located on the printed circuit board; 86L, 86C, 86R latching alarm relays located on the printed circuit board; 86X, 86XL & 86XR control relays located within customer’s control cabinet; 86GL (green/power on) & 86RL (red/alarm) status pilot lights located within customer’s con-trol cabinet.

Any alarm condition, whether vacuum interrupter failure, abnormal CT signal, or loss of monitoring supply power, will cause the 86RL pilot light <alarm condi-tion> to illuminate. Additionally, any single or combination of the latching relays will energize the 86X relay blocking the function of the raise/lower switch while bringing the LTC back to the position from whence it came via the 86XL or 86XR relays, depending on which direction the LTC was moving.

Additionally the function of the CT-Light Conductor circuit within the LTC is con-tinuously verified. Utilizing the input from the AIW (‘All is Well’) microswitch, the circuit checks for signals between the time that the Bypass opens until the Vacuum Interrupter opens. In this situation, CT signals should be present to indicate that the devices (CTs, Light Conductors) and wiring are functional and

Refer to Chapter 3.7 for safety instructions.



all is normal. If any component is not working properly, the associated input ter-minal would not have signals present, and the system would recognize the fault condition. The appropriate phase LED (Yellow) would be illuminated, and the (SP) trip relay would be latched causing the 86RL pilot light to illuminate and locking out the LTC.

If the LTC is to be operated while being “out-of-service”, the Monitoring System is able to ignore the CT-Light Conductor condition allowing tap change without a CT signal. Temporary bypass of the CT-Light Conductor integrity check (Main-tenance Mode) can be initiated with the TEST (Green) and RESET (Red) push-buttons using the following sequence:

1. Press and hold the RESET button for 5-6 seconds to disable the verification system for 10 hours (three yellow LEDs flash slowly). At the end of the 10 hours, the LED's go out and the unit returns to normal function.

2. Push the TEST button to manually exit Maintenance Mode and return to nor-mal function again, as opposed to waiting for the time to expire.

The monitoring system electronics are protected from over-voltage and transi-ent conditions on the power supply by varistor technology and against inadver-tent improper power supply by a traditional in-line replaceable fuse. The moni-toring system is completely functional between 90 & 140 VAC supply voltage.

8.2 Evolution of Design

The original RMV-I vacuum interrupter monitoring system is triggered by a reed switch “RSW” with input to its circuit board at terminal points 19 & 24. This sys-tem remained in production until superseded by the “186” microswitch design in August 1995. The “186” microswitch input to the circuit board was then changed to terminal points 6 & 7. The circuit board at that time was changed to service either construction (universal) by making terminal points 6 common to 19 and 7 common to 24.

A dedicated input circuit board with microprocessor based logic (Model ‘A’) was introduced in September 2002, to supersede the universal input circuit board. It has the “186” microswitch input only at terminal points 6 & 7.

In addition an optional Model ‘B’ circuit board with a secondary microswitch “AIW” input at terminal points 8 & 9 was also introduced in September 2002, to base the Maintenance-Free schedule strictly on operation count intervals regardless of time in service. The Model ‘B’ circuit board was made standard in July 2005 for all RMV’s.



8.3 Installation and Wiring

Due to the close proximity of the terminal points on the circuit board, care must be taken to insure that no loose strands of adjacent circuit wires contact one another. Using wire ferrules or twisting and soldering strands together will help insure that no loose strands contact other conductors. Conductor capacity for the terminal blocks is as follows: Single stranded conductor - 26 to 14 AWG; double stranded conductor (jumpers; sharing) - 26 to 16 AWG.

If larger conductors must be used with the ends reduced by cutting away strands, care must be taken to insulate the cut back strands so they do not short to adjacent conductors! (heat shrink tubing is recommended).



8.4 In-Service Monitoring System Verification

Verification of the monitoring and runback systems can be accomplished while the transformer is energized, with or without load. With the transformer ener-gized, bring the LTC to any bridging position. On a standard position indicator 16L-N-16R, this would be any odd numbered position. In this position there will be enough circulating current to generate a signal through the CT-Light Con-ductor circuit. By simply simulating the closure of the “RSW” or “186” switch while the LTC is on the bridging position, a three phase vacuum interrupter alarm can be generated. This test confirms the LTC internal components are functional. For reed switch “RSW” triggered units momentarily jump terminals 19 & 24 and for “186” microswitch triggered units jump terminals 6 & 7 while the LTC is on a bridging position to perform the test. All three red LEDs must come on and the RESET (red) pushbutton on the circuit board must clear or turn the three red LEDs back off.

The runback circuit may then be checked by initiating a tap change and pushing the TEST (green) button during the movement of the LTC. This test usually requires two people; one at the control cabinet and one at the monitoring circuit board. This should be performed in both the raise and lower direction to verify the runback system. The RESET (red) pushbutton will need to be pushed to clear the alarm condition prior to testing in the opposite direction.

8.5 In-Service Monitoring System Trip (Lockout / 86RL)

If an in-service installation experiences a vacuum interrupter alarm on its own (one, two or three phases), call Reinhausen Manufacturing for support and instruction at 731-784-7681.



8.6 Replacement, Spare or Upgrade Parts

Original Reed Switch “RSW” Triggered System

Fuse for circuit board (1/8A 250V) 58632700

Reed Switch “RSW” 094391

186 Upgrade for RSW units 1A68859

Model ‘A’ Printed Circuit Board 8993C70H01*

Model ‘B’ Upgrade (AIW) 1A68858*

“186” Microswitch Triggered System

(Time-Based Maintenance-Free Interval)

Fuse for circuit board (1/4A 250V) 8991C00H33

“186” Microswitch 1A67580H02

Model ‘A’ Printed Circuit Board 8993C70H01

Model ‘B’ Upgrade (AIW) 1A68858

“186” plus “AIW” Microswitch Triggered System

(Operation Count-Based Maintenance-Free Interval)

“186” or “AIW” Microswitch 1A67580H02

Model ‘B’ Printed Circuit Board 8999C51H01

It is recommended that the printed circuit board be replaced every 15 years, regardless of the vintage or model type.

*Note: If reed switch trigger is retained, the circuit board will require jumpers from 6 to 19 and 7 to 24.



8.7 Monitoring System Vintage Identification

• Original Reed Switch “RSW” Triggered (Dedicated) Circuit

The circuit board for this version of the system has an enclosed signal transfor-mer which is blue in color and has relay covers that are transparent. This circuit board has one green and three red LEDs.

• “186” Microswitch or Reed Switch “RSW” Triggered (Universal) Circuit

The circuit board for this version of the system has an open signal transformer which is yellow in color and has relay covers that are transparent. This circuit board has one green and three red LEDs.

• “186” Microswitch Triggered (Dedicated) Circuit - Model ‘A’

The circuit board for this version of the system has an open signal transformer which is black in color and has relay covers that are also black. This circuit board has one green and three red LEDs.

• “186” plus “AIW” Microswitch Triggered (Dedicated) Circuit - Model ‘B’

The circuit board for this version of the system has an open signal transformer which is black in color and has relay covers that are also black. This circuit board has one green, three red, and three yellow LEDs.

9 Spare parts List


9 Spare parts List

No. Quantity Designation of Parts/Kits RM-item No.

9.1 1 Set of “Hi-Pot Test” Spare Parts (miscellaneous hardware including one Hi-Pot Test insulating panel 6.25 x 6.25 x 0.125 in.)

095 792

9.2 3 Vacuum Interrupter Kit, 1500 A / 2000 A / 2500 A 095 740

9.3 3 Flexible Connector Assembly, 1500 A / 2000 A / 2500 A

095 741

9.4 3 By-Pass Switch Kit 1500 A / 2000 A / 2500 A 095 744

9.5 11

1

1

Access door gasket (single door), 69 kV designAccess door gasket (flanged single door), 69 kV designAccess door gasket (single door), 15 kV / 25 kV designAccess door gasket (flanged single door), 15 kV / 25 kV design

075 879

1A67701H01

8992C01H01

1A67701H02

9.6 11131

LTC Drive Shaft Flange AssemblyGear Box Drive Shaft Seal (large)Endplug (large)Gear Box Drive Shaft Seal (Small)Endplug (Small)

1A67799G01400 310401 828401 676401 827

9.7 11

1

Motor 208-240 V, 60 Hz, single phaseMotor with Thermo Switch (special design) 208-240 V, 60 Hz, single phaseMotor 120 V, 60 Hz, single phase

501154008990C54H01

8990C01H01

9.8 1 Motor Capacitor (Cylindrical) 585 546

9.9 1 Brake Capacitor Set 094 608

9.10 11

Brake Relay (4 Pole)Brake Relay (3 Pole)

8207C39H211A68742H01

9.11 11

Brake Relay Dust Cover (4 Pole)Brake Relay Base (3 Pole)

8207C39H221A68742H02

9.12 1 Test Set: Monitoring System Tripping Device 4D36273

9.13 1 Test Set: Vacuum Interupter Hi-Pot Device 4D36277

Table 5 Spare parts

10 Appendix


10 Appendix

10.1 Drive Mechanism, Standard Mounting

10 Appendix


10.2 Parts Designation: Drive Mechanism, Standard Mounting

10 Appendix


10.3 Drive Mechanism, Ground Level Mounting

10 Appendix


10.4 Parts Designation: Drive Mechanism, Ground Level Mounting

10 Appendix


10.5 RMV-II Load Tap Changer, Operational Sequence Schematic

10 Appendix


10.6 Dehydrating Breather, Dimensional and Installation Details

10 Appendix


10.7 Parts Designation: RMV-II Load Tap Changer, Vacuum Interrupter Assembly

10 Appendix


10.8 RMV-II Load Tap Changer, Vacuum Interrupter Assembly39

RMV-II LOAD TAP CHANGERVacuum Interrupter Assembly

897 152 : 1E

078790 replacedby 452651

078790

10 Appendix


10.9 Parts Designation: RMV-II Load Tap Changer, By-Pass Switch Assembly

10 Appendix


10.10 RMV-II Load Tap Changer, By-Pass Switch Assembly

10 Appendix


10.11 Parts Designation: RMV-II Load Tap Changer, Cam Switch Assembly

10 Appendix


10.12 RMV-II Load Tap Changer, Cam Switch Assembly

2159612/00 • 05/10• F0209300• TL7002.08

©Maschinenfabrik Reinhausen GmbH Telefon: +49 (0)941 4090 0Falkensteinstraße 8 Telefax: +49 (0)941 4090 7001D - 93059 Regensburg E-Mail: [email protected]

www.reinhausen.com

on-load tap-changer rmv-ii 1500 a / 2000 a / … · on-load tap-changer rmv-ii 1500 a / 2000 a /...

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