1zse 5492-152 en rev 1

Oil filter unit for on-load tap-changersManual

1ZSE 5492-152 en, Rev. 1, 1996-03-30

This document must not be copied without our written permission, and thecontents thereof must not be imparted to a third party nor be used for any

unauthorized purpose. Contravention will be prosecuted.

Manufacturer:CC Jensen A/S, Svendborg, Denmark

iii

Recommended practicesABB recommends careful consideration of the following factors when installing an oilfilter unit.

Before you install a unit, make sure that the personnel doing the job have read andfully understood the documents provided with the unit.

To avoid damaging the unit, never exceed the operating limits stated in deliverydocuments and on rating plates.

Do not alter or modify a unit without first consulting ABB.

Follow local and international wiring regulations at all times.

Use only factory authorized replacement parts and procedures.

WARNING, CAUTION and NOTE

WARNINGA WARNING provides information which, if disregarded, could cause injury ordeath.

CAUTIONA CAUTION provides information which, if disregarded, could cause damage to theequipment.

NOTE: A NOTE provides additional information to assist in carrying out the workdescribed.

Safety precautions

WARNINGAlmost all types of oil are potential threats to the environment and as such theyshould not be drained into ordinary sewers and "dumped" in nature. Alwayscheck that all oil carrying components are sealed and tight before operating theoil filter unit.

WARNINGBe aware that oil spillage on the floor around the filter unit is a safety risk!

WARNINGUsed filter elements very often contain harmful substances separated from theoil. Always pack and seal used elements thoroughly until they can be disposed ofin accordance with local regulations.

WARNINGSwitch off the electrical power supply to the filter unit when carrying outmaintenance, and especially before opening the terminal box of the electricmotor and the terminal box of the pressure switch.

WARNINGThe oil filter unit may be hot. Be careful!

CAUTIONDo not expose the filter unit to ambient temperatures higher than 60 °C (140 °F) asthis may harm electrical wires, hoses and other rubber or synthetic components!

CAUTIONThe fluid temperature inside the filter unit must never exceed 110 °C (230 °F). Higherfluid temperatures may cause damage to the seals and packings on and in the filterunit.

iv

Contents1 General information______________________________________ 71.1 Advantages with an oil filter unit ___________________________ 71.2 The oil filter unit ________________________________________ 121.3 Electrical equipment _____________________________________ 121.4 Oil filter circuit _________________________________________ 121.5 Continuous oil filtration __________________________________ 141.6 Filtration medium _______________________________________ 141.7 Service temperature ______________________________________ 141.8 Filter insert replacement intervals ___________________________ 151.9 Leakage in oil filter unit circuit _____________________________ 151.10 Oil level in the on-load tap-changer _________________________ 151.11 Ordering data ___________________________________________ 151.12 Spare parts _____________________________________________ 151.13 Technical specification ___________________________________ 16

2 Installation _____________________________________________ 172.1 General _______________________________________________ 172.2 Tools _________________________________________________ 172.3 Material _______________________________________________ 172.4 Weight ________________________________________________ 172.5 Receiving ______________________________________________ 172.5.1 Unpacking _____________________________________________ 172.5.2 Inspection on receipt _____________________________________ 172.5.3 Temporary storage before assembly _________________________ 182.6 Mounting ______________________________________________ 182.6.1 Plumbing ______________________________________________ 182.6.2 Electrical connections ____________________________________ 19

3 Commissioning _________________________________________ 20

4 Transportation __________________________________________ 21

5 Maintenance ___________________________________________ 225.1 Tools _________________________________________________ 225.2 Material _______________________________________________ 225.3 Annual inspection _______________________________________ 225.4 Maintenance ___________________________________________ 225.5 Filter insert replacement __________________________________ 23

6 Repair ________________________________________________ 246.1 Replacement of pump ____________________________________ 246.1.1 Tools _________________________________________________ 246.1.2 Material _______________________________________________ 246.1.3 Dismounting ___________________________________________ 246.1.4 Remounting ____________________________________________ 256.1.5 Filling up oil in the conservator ____________________________ 266.2 Replacement of motor ____________________________________ 266.2.1 Tools _________________________________________________ 266.2.2 Material _______________________________________________ 266.2.3 Dismounting ___________________________________________ 266.2.4 Remounting ____________________________________________ 27

7 Spare parts list __________________________________________ 287.1 Introduction ____________________________________________ 287.2 Oil filter unit serial number ________________________________ 287.3 Item number ____________________________________________ 287.4 Name of item ___________________________________________ 287.5 Quantity _______________________________________________ 287.6 Remarks _______________________________________________ 287.7 General arrangement _____________________________________ 287.8 Standard spare parts______________________________________ 297.9 Special spare parts _______________________________________ 297.10 Spare parts for oil filter unit _______________________________ 29

8 Restoring the air cushion __________________________________ 29

7

1 General information

1 General information1.1 Advantages with an oil filter unit

All on-load tap-changers manufactured by ABB are designed and tested for service intransformer oil without any kind of filtration. Filtration of the oil is necessary onlywhen normal maintenance is carried out.

However, some advantages can be derived by using an oil filter unit. When the on-load tap-changer is working under onerous conditions such as high switchingfrequency, especially under full load, overloads, etc a lot of dirt is generated in the oilwith an increase in mechanical wear as a consequence. An oil filter unit removes thisdirt and the mechanical wear is considerably reduced. This is of special importance,for instance in furnace transformers.

The clean oil which is the result of the filtration, on the assumption that the filterinsert is in good condition, will also keep the insulation withstand level of the oil veryhigh which gives a large safety margin against flashovers. This might be especiallyimportant when the on-load tap-changer is installed in the line end in high voltagenetworks.

The oil filter unit allows continuous service of the transformer during filtration. Thewiring diagrams in figures 2a-2c show the wiring for the oil filter unit.

The oil filter unit and the filter insert is delivered by ABB. The on-load tap-changer isalso prepared for connection to the oil filter unit. All electrical equip-ment is installedin the motor-drive mechanism cabinet. This means that a larger cabinet for the motor-drive mechanism must be choosen in some cases. The tubes for connection betweenthe oil filter unit and the on-load tap-changer are not delivered by ABB.

This manual gives information for one oil filter unit. In case of two or more units onthe same transformer, all procedures are the same for each one of the units.

8


Pos. Qty. Object

1 1 Pump2 1 Electric motor3 1 Protective roof4 1 Filter insert5 1 Spring housing6 1 Pressure gauge7 1 Top nut8 1 Vent screw9 1 Wing nut10 1 Spring11 1 Filter housing12 1 Stay bolt13 1 Filter base14 1 Drain valve15 1 Sample valve16 1 Pressure switch17 2 Flange18 1 Seal. Viton 295x519 1 Seal. Viton 28.17x3.5320 1 Seal. Viton 28.17x3.5321 2 Seal. Viton 42.3x5.722 1 Seal. Viton 28.17x3.5323 8 M10x40 pin screws

Figure 1. Oil filter unit

9


Figure 2a. Circuit diagram for one oil filter unit.

Figure 2c. Circuit diagram for three oil filter units.

Figure 2b. Circuit diagram for two oil filter units.

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Figure 3. On-load tap-changer type UC with oil filter unit.

Figure 4. On-load tap-changer type UZ with oil filter unit.

tc_00158

Oil filter outlet tube, min. ½"

Oil filter inlet tube, min. ½"

Oil valve Oil valve

Oil valve for draining

Air cushion restoring nipple (option)



Oil valveOil valve


tc_00157

11


Figure 5. On-load tap-changer type UB with oil filter unit.

tc_00159



Oil valveOil valve

Air cushion restoring nipple (option)


12


1.2 The oil filter unitSee figure 1.

The filter unit consists of a filter base, a filter housing, a sampling valve, a motor, apump, and connection flanges.

A drain valve for draining the housing during filter insert replacement, is mounted onthe filter base. There is also a pressure switch, which gives a signal when the pressuredrop over the filter is such that a filter insert replacement is necessary.

The oil pump is mounted on the filter base. The pump is of the gear type. A samplevalve and the motor are mounted on the pump housing.

The filter housing is also mounted on the filter base. It contains the filter insert. A ventscrew and a pressure gauge are mounted on the housing.

The inlet connection flange is mounted on the pump housing and the outlet connectionflange is mounted on the filter base.

1.3 Electrical equipmentSee figure 2.

The oil filter unit needs a power supply to the motor. This is taken from the terminalsin the motor-drive mechanism. The pressure switch has three connections which areconnected to the terminals in the motor-drive mechanism. A motor protective switchwith a trip coil for the oil filter unit motor is also placed in the motor-drivemechanism. The motor protective switch has a status indication contact which showsif the motor circuit breaker is off. It is recommended to connect the "low levelcontact" signal from the oil level indicator on the conservator, so it trips the motorprotective switch by the trip coil. Since the oil filter is working continuously, no otherelectrical components are necessary.

1.4 Oil filter circuitSee figures 3-5. (Figure 3 shows a UCC. The UCG and UCL types have verticalflanges but the connection principle is the same.)

The oil filter circuit is the same for all the different types of on-load tap-changers. Theonly difference is the connection to the on-load tap-changers. The inlet tube isconnected to the UC and UZ on-load tap-changers by flanges on the oil valves. On UBon-load tap-changers, the oil inlet tube is connected to a flange on a tube in the middleof the cover. No valve is mounted. All flanges for the inlet tube have dimensionsaccording to figure 6.

The inlet tube should have a valve close to the oil filter unit to make it possible to shutoff the oil flow in case of filter insert replacement, repair work, etc.

13


a

75 a= 18-25 mm

Figure 6.

Figure 7.

100

55

M10

130

100

75

M12

52

fm_00188

fm_00188

The outlet tube on the UB and UC types of on-load tap-changers is connected to thefree flange on the head of the on-load tap-changer. Dimensions according to figure 6.The position of this free flange may vary, depending on where the pressure-relay andthe tube to the conservator are connected.

The outlet tube on the UZ type of on-load tap-changers is connected to a flange on thetop of the tank, see figure 4. This flange has dimensions according to figure 7. Theexact position is shown on the dimension drawing for the on-load tap-changer.

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In the outlet tube, immediately after the oil filter unit, a valve should be connected asin the inlet tube. After this valve a T-piece with a valve on should be connected, seefigures 3-5. This valve is used to simplify the oil filling and the oil draining.

If the on-load tap-changer compartment is filled with degassed oil and/or theswitching frequency is low, the air cushion in the top of the compartment of UC andUB on-load tap-changers may be dissolved in the oil. To simplify the restoring of theair cushion a valve with an air nipple of the “car tyre type“ can be mounted after thevalve on the T-piece. See chapter 8 for procedure.

1.5 Continuous oil filtrationThe best filtration result is achieved if the filtration is proceeding continuouslywithout interruptions. This method requires also very little control equipment so noextra control cabinet is needed. The necessary components are placed in the motor-drive cabinet.

The maximum power needed is approximately 150 W per unit. The average powerneeded during a life cycle of the filter insert is considerably lower.

1.6 Filtration mediumThe oil filter unit should only be used for filtering transformer oil according toIEC 60296, class II. For other media, please consult ABB.

1.7 Service temperatureThe ambient temperature may vary between -40 °C and +60 °C (-40 °F and +140 °F).Normal operating range for the filtrated oil is from 0 °C to +110 °C (+32 °F to+230 °F). An oil filter unit with a new filter insert can be started with an oil tempera-ture down to -25 °C (-13 °F) without any problem.

If the filter insert has been in service for a while and a pressure drop has been built up,the pressure switch may give alarm when starting at low oil temperatures. This can beavoided by letting the transformer oil be warmed up to at least 0 °C (32 °F) before theoil filter unit is switched on. The pressure switch will trip until the warm oil from theon-load tap-changer has come into the oil filter unit.

If the pressure switch is still tripped after half an hour, wait until the transformer oilhas become even warmer and then start again.

If the transformer is subjected to many starts in very low temperatures (e.g. sparetransformers), make sure that the filter insert is changed frequently.

If the service conditions are such that the ambient temperature is very low (often andduring long periods below -10 °C (14 °F)), the oil temperature of the transformer islow and the inlet tube is long (>3 m), the inlet tube should be insulated.

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1.8 Filter insert replacement intervalAt service on a normal network on-load tap-changer with a low switching frequency(0-30 operations a day as an average) the filter insert is replaced at normalmaintenance, provided that the pressure drop has not exceeded 2.0 bar and thebreathing devices of the on-load tap-changer have worked properly.

The filter insert should be replaced when the pressure drop exceeds 2.0 bar or latestwhen the pressure switch trips.

If the breathing devices of the on-load tap-changer have failed, enough water mayhave entered the on-load tap-changer to saturate the filter insert. In such case, replacethe filter insert.

The pressure drop should be read when the on-load tap-changer is judged to be atnormal service temperature.

1.9 Leakage in the oil filter unit circuitThere is always a risk of leakage in an outer oil circuit, with a too low oil level in thehousing as a result. This risk is reduced by using an oil level indicator with an alarmcontact for low level on the conservator. The signal is used to give alarm in the controlroom, and to trip the motor protective switch of the oil filter unit by activating the tripcoil. See the wiring diagrams in figure 2.

1.10 Oil level in the on-load tap-changerNOTE: When filling oil into an on-load tap-changer with an oil filter unit, fillapproximately 20 l oil in excess into the conservator to avoid refilling afterwards!

1.11 Ordering dataWhen ordering an oil filter unit, the motor voltage and the voltage for the trip coil ofthe motor circuit breaker must be given.

1.12 Spare partsNOTE: Avoid ordering spare filter inserts until they are needed. They can not bestored for more than one year without reduced water removing capacity. See alsochapter 7.

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1.13 Technical specificationMotor: Type: 3-phase, squirrel-cage

Voltage: as ordered by the customerSpeed: 1370-1660 rpmProtection class: IP55

Oil pump: Flow rate: 120-140 l/hOver-pressure valve: Opening pressure 2.8 bar

Filter insert: Type: BNK 27/27Material: CelluloseFiltering grade: 3 µm absoluteSpecially dried for water absorption.Typically pressure drop at 20 °C temperature,new filter insert: <0.1 barMax. storage time: 12 months, with undamaged package.

Pressure switch: Adjusted value: 2.3 barMax. voltage: 230 VMax. current: Res. load 5 A

Ind. load 3 AProtection class: IP65

Noise: <70 dB(A)

Connecting tubes: Min. ½“

Connections: Flange connections, dimensions according to figure 1

Surface protection: The oil filter unit is painted to withstand corrosion category C4according to ISO/DIS 12944-2

Colour: NCS 4822-B05G (= ABB blue)

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2 Installation

2 Installation2.1 General

The oil filter unit should be mounted at ground level in order to enable maintenanceand repair work without de-energizing the transformer.

Figures 3-5 show the valves that are recommended to use in the oil circuit. The airvalve for air cushion restoring is only needed if the on-load tap-changer is filled withdegassed oil and/or is seldom operated.

A special bracket plate has to be placed on the transformer. Dimensions for fixingscrew joint, see figure 1.

For the UC types of tap-changers up to three units can be mounted, one for each OLTC.

2.2 ToolsNormal set of handtools

Small pipewrench

2.3 MaterialA small vessel (oil resistant)

Cleaning paper

2.4 WeightApproximately 50 kg

2.5 Receiving2.5.1 Unpacking

Check that the package is undamaged.

2.5.2 Inspection on receipt1. Check that the oil filter unit, the pressure gauge and the pressure switch are

undamaged.

2. If transport damage is found, and it is judged that correct operation of the oil filterunit is not possible, a damage report should be sent to the insurance company. It

18

2 Installation

is also recommended that photographs are taken of the damaged details. Mark thephotos with ABB’s reference number and the serial number of the oil filter unit,and send them to ABB for comments.

2.5.3 Temporary storage before assemblyIf the oil filter unit is not to be assembled immediately once the delivery has beenapproved, keep the oil filter unit and the oil filter insert in the delivery package.

CAUTIONThe package of the filter insert must not be opened! The special package ensuresmaintained water absorption capacity of the filter insert.

2.6 MountingMounting may be carried out after mounting of the on-load tap-changer in the trans-former factory or at commissioning on site.

2.6.1 PlumbingCAUTION

Do not open the filter insert package at this stage!

NOTE: Plumbing is recommended to be carried out after oil filling of the on-loadtap-changer.

Start by mounting the oil filter unit to a bracket plate on the transformer. Manufacturean inlet tube and an outlet tube as recommended in figures 3-5, depending on whichtype of on-load tap-changer the filter is to be connected to. Dimensions of connectingflanges, see section 1.4 or the dimension drawing delivered with the on-load tap-changer.

The connection points are shown in figures 3-5. UCG and UCL have vertical flangesinstead of horizontal as shown in figure 3 (UCC). Connect the inlet tube to the valvewith flange. For UBB on-load tap-changers there are a flange connection without avalve in the middle of the cover. The outlet tube from the oil filter unit is connected toany of the free flanges.

On UZ on-load tap-changers there is a special flange for oil filter outlet tube, see thedimension drawing for the unit or figure 4 in this manual.

Try to keep the tubes as short and with as few joints as possible. If the tubes are longerthan 5 metres, increase the tube diameter to ¾".

If the transformer should operate on sites where the temperature frequently falls below-10 °C (+14 °F), it is recommended to insulate the inlet tube.

Make sure that all seals are in place before connecting the flanges.

19

2 Installation

2.6.2 Electrical connectionConnect the motor supply and the pressure switch as shown in the wiring diagram infigure 2 in this manual, and the wiring diagram for the motor-drive mechanismdelivered with the on-load tap-changer.

WARNINGMake sure that the voltage is properly switched off before starting wiring work!

It is also recommended to use an oil level indicator with a contact for low oil level inthe conservator, and connect it so a trip from that contact will switch off the motorprotective switch for the oil filter unit, and give an alarm in the control room. See thewiring diagrams in figure 2.

Make sure that the motor has the correct rotation direction by comparing the rotationdirection of the fan with the arrow on the motor.

CAUTIONIf the rotation direction is wrong, the cleaning of the oil will be poor, and in worstcase, a flashover may occur in the on-load tap-changer.

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3 Commissioning

3 CommissioningWhen the on-load tap-changer is filled with oil and all the plumbing and the wiring aredone, the oil filter unit can be started.

CAUTIONIf the oil filter unit is to be dismounted from the transformer during transportation, donot mount the filter insert. In case of dismounting, the oil has to be drained from theoil filter unit and air to be let in. The moisture in the air will reduce the water absorp-tion capacity of the filter insert.

Make sure that all valves are shut. See figure 1. Unscrew the top nut (7) and lift off thehousing. Unscrew the wiring nut (9) and remove the spring (10) and the springhousing (5).

Unpack the filter insert. Check that all the O-rings look good and are correctly placedin their slots.

Put the filter insert in place on the filter base. Before pressing the spring housing (5) inplace, check that the O-ring (19) is correctly placed.

CAUTIONTake care not to damage the O-ring (19) on the thread of the stay bolt duringassembly.

When the spring housing (5) and the spring (10) have been placed, tighten the wingnut (9) first by hand until it touches the spring housing disc, and then an additional 4turns with a spanner, making the insert settle.

Refit the housing, tighten the top nut (7) and the filter is ready to be started.

CAUTIONDo not carry out the filter insert mounting during rain without covering the oil filterunit. Also avoid mounting during foggy weather.

Shut the draining valve in the outlet tube and open the other valves in the inlet andoutlet tubes. Open the vent screw on top of the filter housing (no. 8 in figure 1). Startthe pump.

Close the vent screw as soon as oil appears under it (it will take about 15 minutes). Ifnecessary, fill up the conservator to normal level.

Vent the filter housing again after approximately one hour in service.

Make a final check of the rotation direction of the motor by closing the valve on theoutlet tube slowly. The pressure gauge should show increasing pressure. If it ispossible to shut the valve without pressure increase, the motor rotates in the wrongdirection. Change direction by changing place of two supply wires.


21

4 Transportation

Open the oil valve fully afterwards.

Then switch on the voltage and make a new check of the rotation direction of themotor. When the motor has been checked to rotate in the right direction and the filterhousing has been vented a second time as previously described, the oil filter unit willnow operate without inspection.

4 TransportationThe oil filter unit may be transported mounted on the transformer, provided that it isproperly fixed.

If the unit should be dismounted before transportation, proceed as follows:

Prepare the on-load tap-changer as stated in the applicable guide. The oil level shouldbe lowered in the UC on-load tap-changers.

If the unit has been oil filled, drain as follows:

Shut all valves. Put a bucket under the drain valve (14) and open it and the vent screw(8). Drain all oil from the filter housing (11). The bucket may be emptied before thedraining is completed.

Close the drain tap (14) and the vent screw (8).

Dismount the tubes. Keep the O-rings, the nuts, and the washers. Prefer to use theplastic cover delivered with the oil filter unit on the connection flanges.

CAUTIONOil will pour out from the tubes when they are loosened. Prepare for taking care ofthat oil!

NOTE: The sealing in the flange of the oil filter unit and on the on-load tap-changerwork with “rubber excess“ which makes the O-rings looking somewhat damaged, butthey can be reused provided that they are left in their positions or refitted in the sameposition as they had earlier.

Mount the covers on the return flange of the on-load tap-changers. Mount a cover onthe flange for the inlet tube on the UB on-load tap-changer.

Remove all wirings.


The oil filter is transported in its delivery package which can be reused.

Remounting at site is done by using appropriate parts according to section 2.6.

22

5 Maintenance

5 MaintenanceThe oil filter unit is maintained during the annual inspection of the on-load tap-changer and during the normal maintenance of the on-load tap-changer.

The only maintenance needed is replacement of the filter insert when necessary.

5.1 ToolsAdjustable spanner

5.2 MaterialSpare filter insert

For ordering, see chapter 7 Spare parts list.

5.3 Annual inspectionDuring the annual inspection of the on-load tap-changer, the pressure gauge is read.Note the reading so the change from year to year can be seen.

If the pressure is 2.0 bar or more, or close to 2.0 bar, the filter insert should bereplaced.

If moisture is suspected to have come into the on-load tap-changer compartment, thefilter insert should be replaced.

Also check for leakages. All leakages should be repaired!

5.4 MaintenanceOn-load tap-changers in service in stable networks are normally maintained everyseventh year. In these cases the filter insert should be replaced at every maintenanceeven if the pressure drop is lower than 2.0 bar, if it has not been replaced sometimeduring the preceeding 7-year period.

For on-load tap-changers with a high switching frequency, for instance furnace trans-formers, the filter insert is replaced only when the pressure drop is 2.0 bar or higher,or if moisture is suspected to have come into the on-load tap-changer compartment.

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5 Maintenance

5.5 Filter insert replacementSee figure 1.

Stop the pump by switching off the motor protective switch in the motor-drivemechanism cabinet. Close the valves in the inlet and outlet tubes. Untighten the ventscrew (8) and drain the filter housing (11) by opening the bottom drain valve (14).

After drainage, unscrew the top nut (7) and lift off the filter housing. Unscrew thewing nut (9) and remove the spring (10) and the spring housing (5). Lift up the filterinsert.

When all inside parts have been cleaned and the O-rings (18, 19 and 20) have beenreplaced (they are delivered together with the spare filter), the new insert can beplaced in the housing.

CAUTIONDo not break the sealed package of the new filter insert until immediately beforeinstallation.

Before pressing the spring housing (5) in place, check that the O-ring (19) is placedcorrectly in the slot.

CAUTIONTake care not to damage the O-ring on the thread of the stay bolt during assembly.

When the spring housing (5) and the spring (10) have been placed, tighten the wingnut (9), first by hand until it touches the spring housing disc and then an additional 4turns with a spanner, making the insert settle.

Refit the filter housing, tighten the top nut (7) and the filter is ready to be restarted.Remember to close the bottom drain valve (14).

For restarting, follow the applicable parts of chapter 3 Commissioning.

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6 Repair

6 RepairThe lifetime of the oil filter unit is long. Besides replacement of filter insert, no repairwork should be needed.

However, after long time in service the pump may be worn and needs to be replaced.The motor may also be worn after long time in servie or may be damaged due to over-voltages.

6.1 Replacement of pumpSee figure 1


6.1.1 ToolsNormal set of handtools

Allen key, 5 mm and 6 mm

6.1.2 MaterialPump

O-ring (17 and 22)

Sealing tape

Bucket (oil resistant)

6.1.3 DismountingSwitch off the oil filter unit. Close the valves in the tubes on both sides of the oil filterunit. Disconnect the electrical power supply cable in the terminal box of the motor.

NOTE: Note the phase sequence to get the right rotation direction after reconnection.


Open the vent screw (8) and put a bucket under the drain valve (14) and open it. Drainthe filter housing completely.

Close the drain valve (14).

Disconnect the flange coupling of the inlet tube. Take care of all the nuts and washers.Leave the O-ring in its slot.

25

6 Repair

Unscrew the four caphead screws in the filter housing/pump flange assembly. Takecare of the screws and the washers.

Lift off the pump/motor unit.

Unscrew the four caphead bolts retaining the electrical motor to the pump couplingflange and lift off the motor. Take care of the screws and the washers.

Unscrew the sampling valve from the pump housing.

6.1.4 RemountingSee figure 1.

Clean the threads of the sampling valve. Wind on new sealing tape. Mount the samp-ling valve on the new pump housing. Adjust it in the direction shown in figure 1.

Put the motor in place on the pump housing.

Turn it like in figure 1.

CAUTIONThe shaft of the motor may have to be turned a little, to line it up with the coupling onthe pump. Do not use too high force!

Mount and tighten the four caphead screws and the washers.

Mount a new O-ring (22) between the pump flange and the filter base flange. Fit thepump housing. Mount and tighten the four caphead screws and the washers.

Mount a new O-ring in the inlet flange and mount the inlet tube. Tighten the nuts andthe washers.

Reconnect the power supply cables to the terminal box of the motor as noted earlier.Tighten the cable bushing properly.


Make a quick start and stop of the motor and check the direction of rotation. Thedirection is shown with an arrow on the motor.


If necessary, change the rotation direction by changing place of two phases.


26

6 Repair

Open the oil valve in the the inlet tube and start the motor. As soon as oil comes out ofthe vent screw (8) (it takes about 10-15 minutes), close the vent screw and open thevalve in the outlet tube. Vent the filter housing again after approximately one hour.

Make a final check of the rotation direction of the motor by closing the valve on theoutlet tube slowly. The pressure gauge should show increasing pressure. If not, changethe rotation direction as earlier described, and check again.

Open the valve fully afterwards.

If necessary, fill the conservator with oil to the right level. For procedure, see the nextsection.

6.1.5 Filling up oil in the conservatorSwitch off the oil filter unit by switching off the motor protective switch, located inthe cabinet of the motor-drive mechanism.

Shut the oil valves in the inlet and outlet tubes and on the on-load tap-changer. Loosenthe flange connection on the oil valve of the on-load tap-changer. Connect an oil pumpto the flange, open the oil valve and pump in oil until the level of the conservator isright.

Shut the oil valve and remove the oil filling connection. Reconnect the inlet tube ofthe oil filter unit. Make sure that the O-ring is in place. Open the oil valves on the inletand outlet tubes and on the on-load tap-changer and start the oil filter unit.

6.2 Replacement of motorSee figure 1.


6.2.1 ToolsNormal set of hand tools

Allen key, 5 mm and 6 mm

6.2.2 MaterialMotor

6.3.2 DismountingSwitch off the oil filter unit. Disconnect the electrical power supply cable in theterminal box of the motor.

27

6 Repair

NOTE: Note the phase sequence to get the right rotation direction after reconnection.


Unscrew the four caphead bolts retaining the electrical motor to the pump couplingflange and lift off the motor. Take care of the screws and the washers.

Dismount the plastic coupling of the motor shaft by loosening the stop screw and pullit off. Take care of the key!

6.2.4 RemountingMount the plastic coupling with the key on the motor shaft. Tighten the stop screw.Put the new motor in place on the pump housing. Turn it like in figure 1.

CAUTIONThe shaft of the motor may have to be turned a little, to line it up with the coupling onthe pump. Do not use too high force!

Mount and tighten the four caphead screws and the washers.

Reconnect the power supply cables to the terminal box of the motor as noted earlier.Tighten the cable bushing properly.


Make a quick start and stop of the motor and check the direction of rotation. Thedirection is shown with an arrow on the motor.


If necessary, change the rotation direction by changing place of two phases.


Make a final check of the rotation direction of the motor by closing the valve on theoutlet tube slowly. The pressure gauge should show increasing pressure. If not, changethe rotation direction as earlier described and check again.

Open the valve fully afterwards.

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7 Spare parts list

7 Spare parts list7.1 Introduction

This spare parts list has been compiled to help you with procurement of spares. Toobtain trouble-free deliveries you should note a few things which are explained in thefollowing text.

The breakdown level and general contents of this list have been worked out to covernormal customer requests. Our spares sales people will be happy to assist if yourequire any specific item that is not included in the list.

7.2 Oil filter unit serial numberThe rating plate on the oil filter unit shows the serial number of the device you areordering spares for. It is important to have this information, because the manufactureof parts gradually changes as materials and manufacturing technology improves.ABB makes every effort to supply spares that should fit your require-ments. Someparts of later manufacture than those you are replacing may need some adaption to fitinto your device. Our spare parts sales people need to know the serial number tosupply exactly what you require.

7.3 Item numberItem numbers are shown in the drawings and in the lists.

7.4 Name of itemThe name should be specified when ordering to make sure the right type of item isordered.

7.5 QuantityThe figures given represent the number of items that are fitted to one oil filter unit.

7.6 RemarksInformation of the content and reference to figure 1.

7.7 General arrangementThe general arrangement of an oil filter unit is shown in figure 1.

7.8 Standard spare partsStandard spare parts for the oil filter unit are filter insert, motor and pump.

7.9 Special spare partsIf you need parts other than those in the list, our staff will be happy to assist you.Please use figure 1 as a reference when discussing your requirements. As usual, theserial number are essential for ordering.

7.10 Spare parts for oil filter unitItem No. Name of item Quantity Remarks

1 Filter insert 1 set One filter insert (4) and O-rings (18, 19, 20)

1 Motor 1 set One motor (2)

1 Pump 1 set One pump (1) and O-rings (21, 22)

8 Restoring the air cushionOn UB and UC on-load tap-changers there are an air cushion on top of the housing. Incase of filling with degassed oil and/or low switching frequency, the air cushion maybe dissolved in the oil.

The air cushion must then be restored. On units with an oil filter unit with an oiltubing circuit as recommended in this manual, this restoring is very easy. Proceed asfollows:

The extra valve on the outlet tube (see figures 3 and 5) has an special coupling with anair nipple, as used on car tyres. Shut off the oil filter unit. Shut the oil valve in theoutlet tube and open the valve for the nipple.

Apply a hand pump or an air compressor. Pump in the following approximate volumes:UCG: ~15 lUCL: ~25 lUCC: ~55 lUBB: ~10 l

CAUTIONIf a compressor is used, blow slowly.

If more air than needed is pumped in, it just disappears out via the dehydratingbreather.

Close the valve for the nipple after restoring the air cushion and open the oil valve inthe outlet tube. Switch on the oil filter unit.

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ABB Power Technologies ABComponentsVisiting address: Lyviksvägen 10Postal address: SE-771 80 Ludvika, SWEDENTel.+46 240 78 20 00Fax +46 240 121 57E-mail: [email protected]/electricalcomponents

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Documents

oil filter unit circuit

theoil filter unit

warningthe oil filter

oil filter circuit

oilfilter unit

types of oil

oil spillage

oil level