ce example manual

8/13/2019 CE Example Manual

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OPERATION AND MAINTENANCEMANUAL

HOTSV 69000/145TRANSFORMER

132 / 33 / 11.5 kV VOLTAGE RATIO63 / 50 / 25 MVA RATED POWER


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OPERATION AND MAINTENANCE MANUAL

Table of contentsTable of contents ..................................................................................................................................2

1. General .........................................................................................................................................4

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

1.2 Responsibility of the personnel ..................................................................................................51.3 Safety instructions regarding the oil ..........................................................................................5

1.4 Guarantee ...................................................................................................................................6

1.5 BKT code system .......................................................................................................................6

2. Identification ................................................................................................................................7

3. Technical data of the transformer.................................................................................................8

4. Transportation ..............................................................................................................................9

General .............................................................................................................................................9

5. Lifting.........................................................................................................................................11

5.1 Lifting of total weight ........................................................................................................11

5.2 Lifting of the active part.....................................................................................................11

5.3 Lifting of the bushings .......................................................................................................12

6. Storage........................................................................................................................................13

6.1 General .....................................................................................................................................13

6.2 Storage with oil ........................................................................................................................13

6.3 Storage without oil ...................................................................................................................13

6.4 Storing instructions of bushings...............................................................................................14

7. Commissioning...........................................................................................................................15

7.1 Assembly............................................................................................................................15

7.2 Control of painting .............................................................................................................16

7.2 Oil filling preparation.........................................................................................................16

7.4 Oil filling ............................................................................................................................167.4.1 Oil sampling, oil preparation......................................................................................17

7.4.2 Air release ..................................................................................................................18

7.5 Calibrations ........................................................................................................................19

7.5.1 Buchholz-relay ...........................................................................................................19

7.5.2 Oil- and winding temperature indicators........................................................................20

7.5.3 Air dryers....................................................................................................................20

7.5.4 Oil level indicators .....................................................................................................20

7.5.5 Overpressure protection of the transformer ...............................................................20

7.6 Control of the on-load tap-changer ....................................................................................21

7.7 Activities before energizing ...............................................................................................21

7.8 Energizing ..........................................................................................................................238. Operation....................................................................................................................................24

8.1 Operation above the rated voltage......................................................................................24

8.2 Operation above the rated current ......................................................................................24

8.3 Voltage regulation..............................................................................................................24

8.4 Parallel operation ...............................................................................................................24

8.5 The circuits of the auxiliaries (cooling, protections, current transformers).......................24

8.6 Signals ................................................................................................................................25

8.7 Troubleshooting .................................................................................................................26

8.8 Emergency actions .............................................................................................................26

9. Maintenance ...............................................................................................................................27

9.1 Maintenance work without lifting of the active part..........................................................27


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9.1.1 Oil level indicators .....................................................................................................27

9.1.2 Air dryer .....................................................................................................................27

9.1.3 Thermometers.............................................................................................................27

9.1.4 Buchholz relay............................................................................................................28

9.1.5 Oil pipes and fittings ..................................................................................................28

9.1.6 Cooling.......................................................................................................................28

9.1.7 Bushings.....................................................................................................................28

9.1.8 Tank, earthing screws.................................................................................................28

9.1.9 Gaskets .......................................................................................................................28

9.1.10 Outside painting .........................................................................................................29

9.1.11 Deaerating ..................................................................................................................29

9.1.12 Tests ...........................................................................................................................29

9.2 Maintenance work with lifting of the active part ...............................................................29

9.2.1 Checking of the winding ............................................................................................30

9.2.2 Contaminations...........................................................................................................30

9.2.3 Insulating spacers .......................................................................................................30

9.2.4 Connections................................................................................................................309.2.5 Tap-changer................................................................................................................30

9.2.6 Bushings.....................................................................................................................30

9.2.7 Tank, conservators .....................................................................................................30

9.2.8 Assembly....................................................................................................................31

9.2.9 Test .............................................................................................................................31

9.3 Periodicity of maintenance work and checking of the oil transformers.............................31

9.4 Spare parts ..........................................................................................................................32


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This information indicates particular danger to life

and health. Disregarding such a warning can lead to

serious or fatal injury.

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.

1. General

1.1 Safety instructions

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

equipment must:

be suitably qualified and strictly observe these Operating Instructions.

Improper operation or misuse can lead to

a reduction in the efficiency of the equipment

damage to the equipment and property of the user

serious or fatal injury.

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

information.


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The local management shall inform the operation labour about any hazards which could affect

the health and safety requirements.

1.2 Responsibility of the personnel

All site personnel have to wear appropriate personal protective clothing and equipment to

suit the working environment.

All tools and equipment must be well maintained and suitable for the application.

The delivery of all materials and the subsequent disposal of all wastes shall be carried out incompliance with the current regulations.

Follow all relevant local and international regulations at all times.

Never exceed the operating limits stated in the delivery documents and on the rating plates.

Do not alter or modify a unit without first consulting with the competent supplier.

Use only factory authorized replacement parts and procedures.

Before applying any supply voltage (power, motor, control, auxiliary etc. circuits) check

whether the voltage and the output of the supply are in accordance with the required values.

Do not climb to the cover before the transformer would be out of operation.

For climbing to the cover a ladder is welded on the tank wall if any. Be careful on it to avoid

any accident.

Be careful on the cover to avoid: any accident by stiffeners, cables or tubes

falling to the ground

To avoid any injury do not remove the cover of the OLTC drive shaft.

Must not stay under the lifted parts of transformer!

1.3 Safety instructions regarding the oil

The oil cannot be considered as hazardous material, however it shall be handled in accordance with

current valid industrial hygiene and safety regulations.

First aid measures:

Inhalation: Fresh air

Skin contact: Remove contaminated clothing.Wash skin with soap and water

Eye contact: Rinse with plenty water

On occurrence of pain or redness, consult a doctor.

Ingestion: Rinse mouth and give water to drink.

Obtain medical advice if larger amount has been swallowed.

Fire fighting measures:

The oil is flammable and thus it shall be kept away from naked flames or other sources of ignition.

Extinguishing media: Carbon dioxide, dry chemical or foam.


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During the guarantee period, draying, trearment in oil and all operations that act tank openingmust be carried out by skilled personnel of Ganz Transelectro, otherwise the guarantee will not

longer apply.

Give us the BKT code and the exact type of any kind of parts if you would like to know more

information about the product or ask some spare parts for trouble-shooting.

Do not use water jet. Water can be only used for cooling containers and objects in the area of fire.

Ecological instructions:

Do not allow the oil to escape into canalisation system, waterways, ponds or soil. Collect the

accidental deposits as far as possible mechanically and bind the remains with sand or appropriate

absorbent material and collect.

Environmental instructions

The dangerous wastes must be separeted, stored and transported according to the environmental

specifications of the country and company where the transformer is applied.

The dangerous wastes must be collected separatelly. The content of the vessels shall be indicated

(in case of European countries EWC number must be marked). The dangerous waste must be given

to an authorized carrier with required documents. Reffering documents shall be filed.

Practically the following dangerous wastes can occur:

Dirty transformer oil (EWC 13 03 07)

Oily cloth/ sawdust /perlite (EWC 15 02 02)

Painty cloth (EWC 15 02 02)

Painty package (EWC 15 01 10)

1.4 Guarantee

1.5 BKT code system

The important parts of the transformer are identified by a BKT code system. All BKT code using in

this manual can be found on the Outline drawing.


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Give us the exact type and serial number if you would like to know more information about the

product or ask some spare parts for trouble-shooting. The type and the serial number can be

seen on the rating and connection plate.

2. Identification

Transformer type designation: HOTSV 69000/145

Product serial number: 136482

136483

136484

136485

Year of Manufacture: 2007

Manufacturer: Ganz Transelektro Electric Co. Ltd.

H-1095 Budapest

Mrissy u. 7.

Telephone: (36-1) 483-6754

Telefax: (36-1) 483-6751

Applicable standards:

IEC 60076

IEC 60076-4

IEC 60076-7

IEC 60076-10

IEC 60137

IEC 60044-1

IEC 60214

IEC 60214-2

IEC 60289

EN 60296

IEC 60616

IEC 60815


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We cannot accept liability and exclude any guarantees for damage to equipment, which is due to

the improper operation of the transformer!

The test reports for these transformers are attached to the Operation and maintenance manual.

3. Technical data of the transformer

Main characteristics:

Three phases, core type, ONAN/ONAF cooled, 130 / 33 / 11.5 kV voltage, 63 / 50 / 25 MVA rated

power oil-immersed transformer for outdoor installation with concentric copper winding

arrangement. The iron core is made of cold rolled grain-oriented electrical steel. The on-load tap-changer is connected to the high voltage windings. The transformer is supplied with every fitting,

which is necessary for transportation, operation and protection. The high voltage terminals are fitted

with oil-air bushings. The medium and low voltage terminals are fitted with oil-air bushings and

these bushings are installed in air insulated cable box.

The insulation of the magnetic sheets is carlit. The joint of the limb -and yoke sheets is made

occurred by overlap with 90shearing. Because of the low noise level and core losses, the overlap

of the magnetic sheets is Step-lapped. The tank and cover are welded steel-structure, which are able

to resist 100 % internal vacuum, as well as stresses occurring during transportation (e.g. railways,

roads). There are four jacking pads for hydraulic lifting. There are pulling lugs for lengthwise and

crosswise moving, too. There are 4 ground screws on the lower parts near to the corners of the tank.

Main electrical data can be seen in the Data sheet.

Main mechanical data can be seen on the Outline drawing.


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All information can be found on the Outline drawing for transportation.

Before transportation During the transporatation the tank have to be filled with nitrogen.

During the transporatation the tank have to be filled with nitrogen.

Before dismount any main part of the transformer you have to oparate the valves and gaugesaccording to the commission of the Valve location and function plate.

Centre of the gravity is marked on the outline drawing for transportation.

4. Transportation

General

The transformer was designed for road or railway transportation. It can be transported by means of

trailer of adequate load carrying capacity. Main components have to be dismounted in order to

decrease the size and weight of the transformer body.

The parts to be transported separately are listed on the Outline drawing for transportation.

After careful sealing all the joining openings shall be closed by means of blank plates. Similarly all

detached parts shall be closed.

Attach proper labels on the disassembled parts for clear identification. Use packing adequate for the

application.

Make sure that the quantity of oil specified for the complete oil filling of the transformer is either

transported with the transformer or available at the site of assembly.

Because of the heavy mass and the position of centre of gravity resulting from the relatively high

construction of the transformer as well as the dynamic shocks occurring in the course oftransportation, the transformer shall be firmly anchored with wire ropes and - if necessary - braced

with beams.

In order to prevent the possible damages, the more delicate parts of the transformer shall be

wrapped and/or protected with proper covers.


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Impact indicators or / and one impact recorder will be used to indicate if there was any problem

during transport or handling of transformer.

Impact indicator:

3 pieces impact indicator will be fixed by glue to the tank body to indicate whether the transformer

got any big shock during the transportation. They are in positions according to 3 main directions.

The indicated minimum shock acceleration is 5g (50 m/s2).

Impact recorder:

The impact recorder is installed on the cover. It is firmly secured to the transformer for transport

and handling analysis. This instrument is a mechanical recording accelerometer designed to record

shock and impact from all directions. The number of impacts, the magnitude, the direction and the

time are recorded on a chart paper by means of three independent styluses as follows:

Stylus x lateral shock

Stylus y longitudinal shock

Stylus z vertical shock

Operation: Check the battery. (The maximum recording time of about 180 days can be expected if

the battery is fully charged) Install the chart paper. Remove the stylus guard, set the time and turn

the recorder "on". Finally close and lock the cover.

Note: the chart paper time is marked in one-hour intervals.

Acceptance criteria:

1. The instrument shall be opened and the graphics shall be evaluated in the presence of the

representative of the purchaser and the supplier.

2. The maximum shock acceleration shall not be higher than 5g (50 m/s2) horizontally or

transversally or vertically. If the acceleration has more than one component in variousdirection, then the 5g applies to the resultant acceleration unless otherwise agreed between the

purchaser and the supplier.

3. The impact recorder is and shall remain the Manufacturer's property. PLEASE RETURN IT.


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Must not stay under the lifted parts of the transformer!

Lifting can be performed after the location and fixing of the suitable rope on the component

considering the gravity centre of the lifted part.

Lifting of the active part shall be acc. to the sketch marked onto the Outline drawing!

If you do not use advisable long rope the cover and the active part will damage!

All information regarding the lifting of the active part can be seen on the outline drawing.

5. Lifting

All heavier parts of the transformer are provided with lifting lugs for easy moving and handling.

5.1 Lifting of total weight

Higher lifting of the transformer completely assembled is not possible. For higher lifting of the

transformer not completely assembled (without conservator, pipe lines and bushings but with oil) it

is provided with four lifting pins welded onto the lifting ribs on the tank wall (BQ 030).

Smaller lifting of the transformer completely assembled and full of with oil is possible. There are

four hydraulic jacking pads (BQ 029) at the corners of the transformer tank.

Lifting weight filled with oil is acc. to the Outline drawing.

5.2 Lifting of the active part

For lifting the active part of the transformer, the drained conservator and its pipes about the cover

have to be dismounted. After these the bevel gear and the driving shaft of the tap-changer has to be

disassembled. After these pull down all cable and thermometer connections. Before lifting of the

active part, the oil below the level of the cover has to be drained from the transformer.

The untanking of the active part can be performed by means of four lifting lugs (BQ 031) provided

welded on the cover.


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Catalogues regarding the above mentioned main components are attached to the Operation and

maintenance manual.

All information regarding the lifting of the bushings can be seen on the outline drawing.

5.3 Lifting of the bushings

Before you dismount one of the bushings read carefully the catalogues of the bushings.


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Checking of the oil level or pressure of the nitrogen is very important!

During the inproper storage moisture gets into the tank. The insulation level of the active part

will decrease!

In this case you have to treat the oil!

Before a longer storage more than four week with nitrogen starts you ask the recommendation

of the manufacturer.

6. Storage

6.1 General

Arriving at the site of installation the transformer and its fittings shall be carefully examined to

detect casual damages that could have occurred during transportation. For this the main body and

the packing should, whenever possible, be arranged on a covered and dry place. If there is nopossibility to use a covered place, the packages shall be protected with canvas, at least the bushings

and insulating material shall be maintained in a closed, dry place. When a transformer is received

from the manufacturer, it should be preferably placed in its permanent location to minimize

handling.

All the parts that are not fitted should be unharmed, too. These are to be stored on wooden pillows

in covered store protected against humidity. The components can be stored in transport packing

provided it is considered in good condition. If the bushings must be transported or stored for longer

period it is highly recommended to protect both bushing ends with the plastic covers in which they

were originally wrapped and to use the packing. Check all parts of the transformer also for

mechanical damages.

If the transformer is out of operation for more than two weeks, the heater of the motor drive, control

box and marshalling kiosk / terminal box must be connected and put in service in order to prevent

condensed moisture inside the cabinet. If this is not possible, bags with at least 0.6 kg silicagel must

be put into the cabinet.

6.2 Storage with oil

For long period storage it is highly recommended to fill the transformer with oil and the conservator

is fitted. In the course of longer storage check the transformer monthly whether the oil level is

corresponding to the level relating to the ambient temperature and the air-dryer is effective.

6.3 Storage without oil

For short period the transformer can be storied without oil but filled with nitrogen. Not more than

four weeks it can be storied without any special action. Only the pressure of the nitrogen will be

checked.


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6.4 Storing instructions of bushings

Ordering the bushings, it has to be considered, that the storing conditions recommended by the

supplier cannot always be assured (max. 70 % relative humidity and 15-30 C temperature).

Consequently, the packing has to be suitable for storage in a roofed (but not closed) space for half

year. Suppliers (Haefely, Micafil, Felten, ABB etc.) have to transport the bushings with protection

against humidity.

Above 52 kV the bushings are generally packed horizontally or the head of the bushing is raised by

5. The bottom parts are protected by slab covering, which is filled with oil and screwed to the

flange.

Under 52 kV the bushings are packed in the transporting box cushioned by chips. The lower parts

of the bushings are protected against humidity by sheathing. They are packed into plastic foil. Store

the bushings in the original transporting boxes without disjunction of the packing.

If the supplied protection or the protective covering is injured, the storeman has to arrange the

reconstruction of the same as original protection.

In case of repairing, proceed as follows:

Replace the damaged porcelain insulator, if any. Clean the complete surface of the bushing

by a clean, dry and soft raggy material.

Plastic foil can be used for protective covering, which is rolled up to the neck of the flange

by self-adhesive plastic strip, ensuring the perfect sealing. Damp-asbsorbing silicagel has to

be placed into the protective covering.

Completing the above actions, bushings have to be put on balks with suitable bedding for the neck

of the flange and the outlet-head. The bedding surface has to be varnished by felt or soft rubber

sheet.

If the bushings must be transported or stored for longer period it is highly recommended to lift the

head by 5compared to the flange. In case of such a storage, before using, the bushings has to be

dried in vertical position at approx. 60C for more days. For the right drying technology refer to the

Transformer Division of Ganz Transelektro.

The bushings have to be stored in their original transport boxes till the starting of assembly. The

protection can only be removed directly before mounting.

If the bushings must be stored for longer period it is expedient to fit up the H.V. bushings on thetransformer.


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Minimum 800 mm space will be between the transformer and any wall. In default whereof the

cooling of the tranmsfomer will not be satisfying.

Be careful! Do not drop down any object into the tank! Metal parts cause short circuit in the

winding, connection or on the surface of the core.

7. Commissioning

7.1 Assembly

A solid foundation suitable to the total transformer mass shall be provided for assembly. On the

site, where the transformer will be installed the air shall be able to circulate freely to allow the

cooling system to actuate appropriately during operation and the temperature to remain within the

limits foreseen in the project.

Put the transformer on its foundation and remove the protecting covers, the packing and banding

materials. The radiators, the conservator and the pipes shall be perfectly clean and dry, the devices

shall be unharmed before assembly. Before fitting each part of the transformer each device shall be

thoroughly checked and cleaned. If compressed air is available, all groves, corners, holes and other

cavities shall be blown off. The insulators and live metallic parts are wiped with specified rags and

cleaners.

All parts removed for transportation are identified by appropriate marks, which are reproduced in

the shipping lists. These are to be installed as shown on the overall drawing.

The insulating oil delivered for the transformer is acc. to IEC 60296. Before filling of the

transformer the oil must be properly tested.

Remove the blind flanges one by one and fit all the components. During these operations take good

care to avoid moisture, any type of contamination, foreign object to get into the transformer throughthe opening just free for assembly.

Before starting the operation materials and tools needed for possible danger averting must be

prepared. Tray must be placed under the location of possible oil leakage. To clean the little oil

spots, cloth, perlite, broom and shovel shall be put out.

The clothes and sand used for oil absorbing are dangerous wastes. They must be collected

separately, transported and handled properly after finishing the operation.


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Set all the valves according to the instruction of the Valve location and function plate!

The gasketed flanges are to be overbridged for earthing. Make the earthing link of the transformer

to either of the earthing screws provided on both sides of the tank at the bottom. Finally make the

connections of high and low voltage cables and those of the auxiliary cables.

Complete the oil filling of the transformer, the tap changer.

Release the trapped air.

Set the oil levels in the conservator chambers to the actual ambient temperature.

7.2 Control of paintingCheck the transformer carefully. If there are mechanical failures, painting defects, repair the failures

and the painting defects, replace the fixing elements if there is any corrosion on them. Do not put

the transformer into operation without repairing the failures.

7.2 Oil filling preparation






Remove the blind flanges one by one and fit all the components. During these operations take good

care to avoid moisture, any type of contamination, foreign object to get into the transformer through

the opening just free for assembly.

The value of the vacuum in the transformer tank under oil filling shall be 667 Pa (5.0 mm Hg).

7.4 Oil filling







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If the transformer is not filled with oil completely, proceed as follows:

Open the upper and lower butterfly valves (AB 230) of radiator groups. These are opened when

marking on the shaft ends are collinear with the axis of pipe.

Drums of oil are provided for each transformer for the first filling in of the adequate oil level. The

oil shall conform to IEC 60296. In case of extra oil is required the vast majority of other insulating

transformer oil of mineral oil basis satisfying the requirement of IEC 60296 can be used. In case ofdoubt make use of a mixing test carried out by a special laboratory or refer to the Transformer

Division of Ganz Transelektro. Before being used the drums shall stand for minimum 2 days

without moving. Before the oil utilization it must be tested for electric strength, moisture content

and gas content. The oil before filling in to the transformer shall comply with the values below:

Electric strength: > 200 kV / cm

Moisture content: < 15 p.p.m. (measured acc. to IEC 60814)

Gas content: acc. to IEC 60422

In case the results do not reach the specified minimum values, the oil shall accordingly treated

before its utilization. For this use a filter and processing equipment type Micafil or certifiedequivalent. Take care that the oil quality is not effected by dirty filling devices, and hoses.

Fill the transformer with oil of adequate quality via the oil filling pipe of the conservator. The oil

filling should be continued until the oil-level indicator shows the highest level. In this way the

conservator will be nearly full. This can provide enough oil for deaeration. If the oil level decreases

for any leakage, check the place of leakage and stop the untightness.

The separated oil space of the tap-changer - if any - can be filled through the filling opening of the

conservator compartment connected to the tap-changer. Proceed with the filling as far as the oil

level indicator of the separate oil space will show the level relating to the ambient temperature.

Then close the oil filling valve.

7.4.1 Oil sampling, oil preparation

The dirty oil arising during the operation is dangerous waste. It must be collected separatelly,

transported and handled properly after finishing the operation.

Oil sampling is made through oil sampling valves (M12 and DN25). Oil samples have to be taken

from the transformer tank and from one radiator group, separately into sampling vessels.

On the tank you find the oil sampling valve(s) shown by the Outline drawing

On the radiator the sampling valve (AB630) is installed onto the bottom collecting pipe of the

radiator.

Oil sampling procedure:

Clean the outside part of valves carefully to avoid oil contamination in the vessel. To ensure the

cleanliness 4-5 litres oil has to be let out. Part of this oil is used to rinse the cleaned, dry vessel two

or three times, then fill the vessel with bubble free, foamless oil until completely full, taking care

for cleanliness to avoid dust contamination and moisture.

Cover the vessel with a clean, dry glass plate and leave it until no more air bubbles are released.

The oil has to satisfy the IEC 60296 standard. If the oil test shows that there is moisture in the oil


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Do not forget to close the deaeration openings!

The oil will flow through the opened vent hole!

for some reason, then the oil has to be treated. In this case the oil has to be suctioned through the

bottom draining valve (AA355), then through the oil filter and treatment equipment, heated to 50-

55oC with the heater of the equipment, the oil has to be refilled into the transformer through the oil

filling valve (AA356). The treatment may be finished if the breakdown withstand strength of oil is

higher than 200 kV/cm and the oil satisfies the requirements of the relevant standard.

In case of local assembly the transformer can be energized if the oil sampling and the oil

examination was done according to the above description, and the oil property is suitable for the

specified values, furthermore, less than a month passed from oil sampling to energizing. If more

than a month passed, the oil sampling and examination has to be repeated. If the oil properties do

not suit the description, the oil has to strain and vacuum dry to achieve the specified values.

7.4.2 Air release

After filling the transformer with oil the transformer has to be deaerated. If oil filtering - to remove

impurities and moisture - was necessary, the deaeration should be repeated after this procedure.

Open all the vent openings (AB 600), on the cooler-groups (installed the bottom collecting pipe of

the radiator), on the pipes if any, on the head of the tap-changer, on the relays, on the bushings if

any and release the trapped air. The deaeration can be finished if foamy oil, air-bubbles stop

flowing out of openings.

Then the transformer should rest for a period of 24 hours to enable any trapped air to be released.

Then it is necessary to deaerate again. During resting do not switch-on the transformer. The

deaerating is good, if air does not accumulate at the venting places at 40 C oil after 6 hours, at min.

10 C oil after 72 hours. After deaerating any missing oil must be replaced through the conservator.

Check if the oil levels in the conservator chambers are corresponding to the actual ambient

temperature. Add or drain oil as necessary.


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It is very important to make sure their right operation!

Improper operation causes damage of the transformer!

Connect the trip signal of the Buchholz relay to the transformer main circuit breaker or to the

protection system!

7.5 Calibrations

After connecting the protection relays and other auxiliary devices, they have to be actuated.

7.5.1 Buchholz-relay

The transformer tank is protected by a Buchholz-relay. The relay is mounted into a pipeline, which

places between the tank and the conservator. The relay has 2 floats. The upper float signals gas-

forming and oil bleeding. Smaller faults cause weaker gas-forming, bigger faults cause more

increased gas-forming. Therefore, the lower float operates in case of bigger oil bleeding and more

increased gas-forming, furthermore gives tripping signal. The bigger internal faults cause verystrong gas-forming and/or oil stroke towards the conservator, which also gives tripping signal by

moving of a sheet (placed in the oil-flow).

That oil flow velocity may be set, where the relay switches. On the site of the transformer can be

found an inspection cover whereby may be checked the oil level in the relay. The gathered gas in

the relay may be let out and examined.

Checking of the Buchholz-relay:

The upper cap has to be taken off. Unscrew the cover of the Buchholz-relay, and press the

protruded actuating rod 10 mm down. At this time, the contact of the upper float shall be closed and

gives alarm. After this, further 10 mm press down, then the contact of the lower float shall be closed

and gives alarm. The contact of the upper float has to be used for alarm, the contact of the lower

float has to be used for tripping.

Checking of the Buchholz-relay may be occurred by air pumping across (E) valve. In both case can

be followed the moving of the floats across the inspection covers on the site of the relay.

The gathered gas amount in the relay for alarm: 200 cm3

Tripping occurs only if

the gas-forming is continued or/and

the velocity of the oil-flowing from the tank to the conservator exceeds 1 m/s.


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Connect the trip signal of the pressure relief devices to the transformer main circuit breaker or to

the protection system!

Connect the alarm signal of the oil level indicators to the protection system!

Connect the trip signal of the oil and winding temperature indicator to the transformer main

circuit breaker or to the protection system!

7.5.2 Oil- and winding temperature indicators

Alarm and trip signals are acc. to the Cooling control drawing.

The built-in adjuster unit of the winding temperature indicator forms the winding temperature by

the sign of the current transformer. For connection see the Cooling control drawing.

7.5.3 Air dryers

Check the silicagel filling of the air dryer. If the filling has turned green, then replace the filling

with new one or empty the air dryer and dry the silicagel for several hours at 110-115C

temperature, until it turns evenly orange. Then mount the air dryer with the renewed filling back to

its pipe. Check the lower oil seal. If it is not enough, fill it to the red marking line.

7.5.4 Oil level indicators

The oil level indicators of the conservators are provided with two microswitches, which can be used

for signalling when the oil level reaches the maximum and the minimum levels respectively. It is

calibrated to +20 C.

7.5.5 Overpressure protection of the transformer

A pressure relief device is placed on the cover of the transformer for releasing the overpressure due

to a possible internal failure. It is essentially a springloaded valve. The valve operation is effected

when the opening pressure exceeds the value of 0.5 bar. The pressure relief device is provided with

a sealed, weather-proof alarm switch. A bright colour indicator pin on the top shows that unit has

functioned. The pin may be reset by manually pushing it downward.


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See also the Technical Instruction of the tap changer and the motor drive.

The checklist is attached after this Manual.

7.6 Control of the on-load tap-changer

Check the positions and the assembling of the driving shafts (between the tap-changer and drive

control box). The tap-position mark has to be seen same in the drive control box and the tap-

changer head. The motor drive control complies to the principle of step by step switching, i.e. one

single control impulse starts each switching step.

If the motor drive is out of operation for more than two weeks, the heater must be connected and

put in service in order to prevent condensed moisture inside the cabinet. If this is not possible, bags

with at least 0.6 kg Silica gel must be put into the cabinet.

7.7 Activities before energizing

Before energizing the transformer the following tests and controls must be performed:

a. The bushings have to be carefully cleaned.

b. Check the right phase sequence compared to the network.

c. Measure the insulation resistance of transformer windings. During the measurement the

terminals shall not be connected to the network. The insulation resistance measurementshall be performed with a 5 kV insulating tester. The winding, which is not tested, must be

earthed together with the tank. The results of measurements made at the manufacturer's test

room (see Test Certificate) and on the site have to conform.

The values of insulation resistance varies highly in function of time and temperature.

Apply the durations indicated in the Test Certificate (15 s and 60 s).

For temperature correction use the formula below:

(Where C (T) is the correction factor.)

R (20 C) = R (T C) x C (T C)

The C (T) function can be given by the approximate equation as follows:

C (T) = 0.3 x e 0.06.T

d. Voltage ratio measuring by 400 V to verify flowing of the sequence of the regulating taps.Check, whether the tapping voltages are in accordance with the voltages indicated on the

connection scheme. If there are any deviations, the operator must inform the

manufacturer.

e. Check the right operation of the motor drive, if applicable.f.Check the right operation of the tap-changer, if applicable.


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g. Check the right connection of cables mounted onto the transformer, into the protecting and

indicating equipment and into the terminal box.

h. Check if the dielectric strength of the oil is adequate.

i. Check if the oil levels in the conservator are correct.

Check if the air-dryer is filled-up completely with silicagel. The colour of silicagel is

orange if it is dry. If the filling is oily, replace it with new filling. Check the lower oil seal,

that the oil volume is enough or not. If the oil level does not reach the red line, then oil

must be added.

j. Make sure that all valves between the conservator and the tank and the cable boxes

respectively, if any, are open.

k. Make sure that all valves between the tank and the radiator banks are open. Make sure that

all draining valves, filling valves, air release openings and sampling valves are closed.

l. Make sure that the thermometer pockets are full of oil.

m. Check if all bushings are fully vented and are duly clean.

n. Check the right operation of the auxiliary control box.

o. Check if there are connected loads to the current transformer secondaries, otherwise they

shall be maintained in short circuit.p. Check if the contacts of Buchholz relays, protecting relay, oil level indicators,

thermometers and other relays act correctly on the alarm and tripping circuits.

q. Check the wholeness of protective links of mounting panels, devices, cable armouring and

equipment placed on the transformer.

r. Check the connection of earthing terminals and links of transformer. Check carefully the

tightening of screwed connections.

s. Make sure there are no foreign materials on the transformer, specially on the cover.


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During energizing follow the safety regulations of country and local authority.

Improper procedure before or during the energizing causes the damage of the transformer or

injury of the operating labour

Before putting the transformer into operation set all of protection and control equipment to be

ready for operation.

In case of differences detected between the results recorded and the values specified inform the

Transformer Engineering Department of GANZ TRANSELEKTRO.

7.8 Energizing

Safety regulations

The setup procedure and the operation must be performed by personnel having qualification and

authorization. The results of technical checking and tests must be recorded.

The voltage has to be switched on to the transformer -if it is possible- from the High Voltage side.


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8. OperationThe transformer is designed for the continuous operation at rated voltage and current assigned to

each tapping position as specified in the data sheets in normal service conditions. Wave shape of

the supply voltage has to be practically sinusoid, its frequency 50 Hz. The three phases has to be

practically symmetrical.

8.1 Operation above the rated voltage

The permitted maximum continuous operation voltage is 105%of the rated voltage referring to the

actual tap-position.

8.2 Operation above the rated current

The general limitations and effects of loading beyond the nameplate rating shall be considered as

specified in the Loading Guide for Oil-immersed Power Transformers issued by IEC 60076-7.

8.3 Voltage regulation

The voltage regulation of the transformer is realized by means of a motor-driven on-load tap

changer installed in the tank. The on-load tap changer has the function to change the transformation

ratio by adding the turns of the regulation winding to the turns of the high voltage winding while

maintaining the load conditions of the transformer unchanged.

The type of the on-load tap changer is acc. to the Outline drawing or Rating and data plate.

The motor drive control complies to the step-by-step switching, i.e. one single control impulse

starts each switching step. After giving a control impulse the step movement will be commenced

and it will be accomplished automatically without any interruption. The next control impulse is

only observed with the control system being in rest position again.

The type of motor drive unit is acc. to the Outline drawing.

The on-load tap changer driven by the motor drive can be operated in the following ways:

- by hand with crank kept in the motor drive

- with push-buttons located in the motor drive

- with push-buttons located in the remote control panel (if provided)

- automatically using an Electronic Voltage Regulator (if provided) The "raise" or the "lower"

control signal is generated by the voltage regulator and issued to the motor drive whenever the

measured voltage of the network deviates from the preset conditions.

If the motor drive is out of operation for more than two weeks, the heater must be connected andput in service in order to prevent condensed moisture inside the housing. If this is not possible, bags

with at least 0.6 kg silicagel must be put into the housing.

8.4 Parallel operation

Two or more transformer in case of parallel operation, each transformer has to be in equal voltage

value and vector group.

8.5 The circuits of the auxiliaries (cooling, protections, current transformers)

The circuits of auxiliaries and the terminal strips are shown in the Documentation. Describing of the

devices can be found in the catalogues, the adjusting values are in the chapter of Calibrations (7.5)


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Connect the trip signal of the devices to the transformer main circuit breaker or to the protection

system!

8.6 Signals

Alarm signals are given acc. to the drawing Cooling control:

Trip signals are given acc. to the drawing Cooling control.


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8.7 Troubleshooting

The following trouble checks will help to correct the most common problems encountered with the

transformer operation. The transformer shall be put in operation again, only after the cause of

problem has eliminated.

Problem Probable Cause Action

Alarm signal of oil level

indicator

Low oil level due to leakage Stop oil leakage and add oil

Alarm signal of oil level

indicator

High oil level due to high oil

temperature

Check the transformer load,

the fan operation and the

radiator valves

Alarm signal of high temp. in oil

or winding

Transformer overloaded,

radiator valves closed

Check the transformer load

check the positions of valves

Alarm signal of Buchholz relay Gas development or oil

leakage

Check the gas of relay, find the

cause of trouble or stop oil

leakage

Alarm signal of cooling Fans are out of operation Check the operation of fansand the switches, contactors in

the control box

Trip signal of high temp. in oil or

winding

Transformer overloaded Check the transformer load

Trip signal of Buchholz relay Gas development, oil

leakage/flow

Check the gas of relay find the

cause of trouble

Trip signal of protective relay Oil flow from the tap changer Check the tap changer to find

the cause of trouble

Trip signal of

pressure relief device

High internal pressure

due to internal trouble

Check the transformer, make

ratio and insulation test, find

the cause of troubleTrip signal of differential or earth

fault protection

Internal trouble Check the transformer, make

ratio and insulation test find

the cause of trouble

8.8 Emergency actions

When alarm signal are given

The time and conditions of signalling shall be recorded. Find the cause of signalling in order to stop

any incorrect operation and to avoid tripping.

When trip signals are given

The time and conditions of signalling shall be recorded. Find the cause of tripping and eliminate thecause of troubles.

General

Performance data, overvoltages, short circuits, alarm and trip signals, misoperation of other electric

devices and all important events related to operation, tests, inspections shall be registered in a log

book.


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Generally small welding works on oil filled tanks can be performed safely by skilled workman.

9.1.4 Buchholz relay

Check the Buchholz relay for leakage and proper seat.

If one of its two contacts cannot operate well, the relay has to be replaced with a new one. Check

after each signalling whether the gas collected in the relay is combustible. If the gas is combustible

the transformer may be suspected of failure. It is expedient to analyse the gas before energizing the

transformer.The relay does not require special maintenance, but before putting into operation check the

reliability of the operation.

During the troubleshooting the volume of the tank and the conservator can be connected via a bay

pass pipe connection, if any.

9.1.5 Oil pipes and fittings

Replace any missing items, tighten the gaskets to stop any oil leakage.

9.1.6 Cooling

Check the radiator elements and butterfly valves for leakage and mechanical failure. Stop eventual

leakages with tightening or replacement of sealings. Check the cleanliness of radiating surface.

Remove any contaminations, clear out the blocking of air routes.

Check the operation of the fans.

Remove all dirt and dust from the fan wheels.

The motor bearings do not require any lubricant.

The checks of the control box acc. to the operation instruction.

9.1.7 Bushings

Check the tightening of all screwed connection. Replace the damaged porcelain insulator, if any.

Clean the complete surface of the bushing. Make sure that the connected cables do not load the

bushing.

The storage, the transportation and the maintenance of the bushings are detailed in the

Appendix 6.4

9.1.8 Tank, earthing screws

If the tank is dangerously uneven or battered, or there is oil leakage on it, the transformer has to be

transported into a workshop for repairing. Replace damaged earthing screws.

9.1.9 Gaskets

Check carefully all the gasketed joints of the transformer for oil tightness. The gasket does not

require maintenance work.

If you happen to find any oil leakage eliminate the leakage considering the followings:

- The oil leakage is usually indicated by oil drops.

- To find the exact spot of the leakage wash the outside surface at and around the leakage withpetrol and paint it with chalk or other indicating material.

- Try to eliminate the oil leakage with tightening the screws clamping the gasketed surface inquestion. Take care to even increasing of clamping pressure, which can be achieved by


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Must not stay under the lifted parts of the transformer!

Lifting can be performed after the location and fixing of the suitable rope on the component

considering the gravity centre of the lifted part.

tightening the screws which are diagonally facing one another on the periphery, in succession.

Continue this procedure as necessary.

- If the leakage can not be stopped with the procedure detailed above or the gasket is damagedreplace the gasket with new one.

Always degrease the surfaces to be contacted with the gasket.

The gaskets are made of heat- or oil permanent rubbers. For instance O-rings, flat gaskets, silicone

rubber rings. D-profile rubber string can be used between the tank and the cover.






9.1.10 Outside painting

Check carefully the surface of the transformer and the fittings to find the eventual painting defects.

If there is any small defect in the painting, remove the base and final coast and the rust around the

defect.

Clean and degrease the damaged areas back to bright metal and apply primer coats immediately.

Use the final top coat of the same colour specified for the contract.

If there are many defected areas or those are big, paint again the whole tank with approved paint

system.

After finishing the painting the empties, remaining paint and painty clothes are dangerous

wastes. They must be collected separately, transported and handled properly after finishing

the operation.

9.1.11 Deaerating

After maintenance deaerated the transformer as described in the section "Commissioning" (7). The

missing oil shall be replaced.9.1.12 Tests

After the maintenance works (without lifting of the active part) has to be measured the insulation

resistance and the ratio of the transformer.

9.2 Maintenance work with lifting of the active part


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Untanking:

Before untanking make new gaskets, spare bolts and the damaged or missing parts available. Ensure

with continued heating that the temperature of the transformer's active part is at least 5oC above the

ambient temperature.

The untanking of the active part can be performed by means of the lifting lugs (BQ031) fixed on the

stiffeners of the cover.Before loosening the bolts of the cover drain approx. 2000 l of oil from the transformer tank. Take

care of the vertical lifting of the active part to avoid accidental damage. After lifting out leave

enough time to drop the oil from the lifted part into the tank. Then put it - if possible - onto a

bordered iron sheet for investigation.

9.2.1 Checking of the winding

Check the insulating material of winding for eventual brittleness and fragility. If it is so, no need

any other tests as the winding has to be rewound, the transformer has to be delivered into a

repairing workshop.

9.2.2 Contaminations

Clean the active part of transformer with a soft brush or cloth, then wash it with oil jet at 50-60oC,

to remove the contaminations. Use transformer oil of standard quality.

9.2.3 Insulating spacers

Check, whether the winding clamping, the spacers between the winding and the end insulations are

eventually loosened. If these are loosened, ensure the fixing tightening.

9.2.4 Connections

Check the connections for eventual displacement, or if these are dangerously near to other

construction part. If it is so, ensure reparation of the failure, and fix the connection, if necessary, to

avoid repeated failure. Check the bolts, nuts, rivets, brazed points and welded points and repair any

eventual failures.

9.2.5 Tap-changer

The maintenance of the tap-changer has to be performed according to the related Operation and

Maintenance Manual. Check the tightness of bolts fixing the connections between the tap winding

and the tap-changer.

9.2.6 Bushings

Clean the surfaces of bushings, replace any damaged on the bushings.

9.2.7 Tank, conservators

Drain the oil from the tank, and clean carefully the empty tank. The necessary repairs must beperformed only after cleaning. If any welding is necessary, ensure the good ventilation of the tank.

For welding operations apply electric welding. Use heavy-coated rutine-cellulose type electrodes of

2.5-4 mm diameter according to the Standard ISO 2560/DIN 1913.

If there is any rust in the tank, on the inner part of cover or inside the conservator, then clean the

rusted surfaces with wire-brush, degrease, and paint the surfaces exposed to rust with oil resisting

varnish.


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9.2.8 Assembly

The active part of transformer, if there is any possibility at the site, has to be heated in short

circuited state, it has to be dried and put into the empty tank. After putting all the gaskets discharge

filtered oil heated to 50-55oC into the tank under vacuum.

After placing the transformer on the base heat the transformer in short circuited state and filter the

oil as long as moisture can removed by the filter apparatus.After resting and deaerating carry out oil test.

When putting the transformer into operation follow the instructions of commissioning given in the

Section 7.

9.2.9 Test

The following tests have to be carried out after maintenance of the transformer:

- visual inspection

- functional test and calibration of all measuring, control and protection equipment

- Megger test on all windings against each other and against earth

- measurement of voltage ratio at each tap position and check of voltage vector relationship- dielectric test of oil and analysis of moisture content

- if it is practicable perform the following:

dielectric test with power frequency test

voltage, but the voltage has to be 75% of the rated value.

9.3 Periodicity of maintenance work and checking of the oil transformers

The maintenance and inspection of the transformer have to be performed in the intervals indicated

in the following table:

Subject of checking Periodicity of maintenance work

Oil level monthly

Oil level indicator

Conservator

Breathing openings

monthly

Air dryer monthly

Gaskets monthly

Thermometer yearly

Buchholz relay

Protective relay

Pressure relief device

yearly and after each

operation

Oil fittings yearlyCoolers, control boxes, motor or manual drives yearly

Terminal connections, bushings yearly

Outside painting yearly

Tank yearly

Oil sampling and oil test prior to energizing, then after half year,

subsequently every two years.

Occasionally in case of operating

Deaerating after oil supplement and replacement


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9.4 Spare parts

Request for spare part

The request for spare parts or materials or service should be addressed to the nearest Representative

of GANZ TRANSELEKTRO complete with the information as follows:

Transformer type designation

Serial number of the transformer Year of construction

Exact type of the requested device or part

BKT code

Quantity

Plant address

Others: fault nature and causes etc..


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