td-tsp manual

7/29/2019 TD-TSP Manual

1/19

TD-TSP-0004-2A (1/19)

INSTRUCTIONS

MAINTENANCE FOR

POWER TRANSFORMER

Address No. 23, Chung-Hwa Rd., Huko Hsiang, Hsinchu, Taiwan 303, R.O.C.

URL http://www.seec.com.tw TEL +886-3-598-1921 FAX +886-3-597-6373


2/19

TD-TSP-0004-2A (2/19)

1. FOREWORD

Power transformers are getting larger in their capacity to meet increasing power demand. So emergency

or unexpected power demand due to transformer trouble cause much loss of production as well as

inconvenience.

Therefore it is essential to assure trouble-free performance by a well-planned maintenance program.

Daily or periodical inspections will result in detecting abnormal conditions of a transformer and parts

before they cause any more serious troubles. A regular program of inspection should be established and

rigidly carried out for preventive maintenance of power transformers.

This instruction book describes inspection and maintenance methods to keep transformers in good

condition. As for construction, functions and handling of accessories, the corresponding instruction book

should be referred to for more detailed information.

2. REQUIREMENTS FOR INSPECTION AND MAINTENANCE

2.1 General

(1) The inspection items are classified into three categories in this instruction book.

(a) Routine inspection items (Table 1)

The routine inspection should be made, preferably daily, on every transformer in service.

Especially oil leak, oil temperature and/or winding temperature, load current, ambient

temperature and oil level in transformer should be daily checked and recorded.

(b) Periodical inspection items (Table 2)

The periodical inspection should be made each item, at least once every six months to once

every three years in order to ascertain the good performance of a transformer and its parts. Most

of the periodical inspections should be made in detail when the transformer is de-energized.

(c) Additional inspection items (Table 3)

Some additional inspections or measurements of electrical characteristics of a transformer are

recommended as preventive maintenance actions and when any transformer trouble should be

investigated thoroughly.

(2) Repainting of radiators and transformer tanks, and exchange of parts, gaskets and bearings of motors

should be planned and prepared previously for preventive maintenance, which will result in

continuous good performance of transformers. (Refer to Table 4)


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TD-TSP-0004-2A (3/19)

(3) If any protective relays give alarm, investigate the trouble causes according to Table 5 and Table 6.

It is essential in investigating the right causes to check whether differential relay, overcurrent relay

and/or ground fault relay have operated or not, in combination with other relays such as Buchholz

relay, sudden pressure relay and pressure relief device, which have physically operating

mechanisms.

(4) Transformer should be inspected internally whenever they have been subjected to unusually severe

operating conditions such as overloads and frequent short-circuits of outer bus or transmission line.

(5) Any symptoms such as unusual noises, high or low oil levels, rupturing of bursting plate, etc., should

be investigated thoroughly.

2.2 Inspection records

(1) The establishment of the report and recording of the condition and repair of the transformers is

required for a good maintenance program.

(2) A preventive maintenance system will operate satisfactorily with the following records.

(a) An equipment record

This may be simply a card, which contains the basic information of a transformer itself such as

the serial number, the location, size, etc.

(b) A repair record card

This may keep a running record as to costs of maintaining a transformer. It is the essential

diagnostic record for avoiding future difficulties.

(c)An inspection check list or inspectors record

This may be simply a listing of the points to be checked on a transformer and the establishment

of the time that these checks should be made.

(3) Without these records it would be very difficult for a preventive maintenance program to work,

because the knowledge gained form regular inspections would be quickly lost.

2.3 Actions for safety

Always inspection and maintenance works are to be done very carefully so that their schedule should

be planned in detail in view of safekeeping of human life and equipment according to APPENDIX I.


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TD-TSP-0004-2A (4/19)

3. INSPECTION

3.1 Routine inspection

At least item 1 should be checked daily and recorded.

Table 1

No. Items Method ActionOil temperature

and winding

temperature

Read indications of dial and/or

alcohol thermometers, and winding

thermal relays, if provided.

Compare them with the data

previously obtained.

When oil and/or winding

temperature

are much higher or lower

considering load current and

ambient temperature,

Thermometers should be inspected.

1

Load current

Ambient

temperature

Load current and ambient

temperature should be recorded at

the same time.

Check if indication of a thermometer

is correct or not.

If the temperature is not correct,

exchange with a new one.

If oil temperature is too high due to

dust and other foreign materials on

the finned area of radiators or the

inner surface of cooling water tube

(In case of water cooler type) clean

up them.

If indication of thermometer is not

correct, check oil level in the sensor

pocket and adjust to correct the

level.

2(1) Oil level

See note.

Read indication of the dial oil level

gauge on the conservator with a

telescope.

Compare it with the oil level-oil

temperature curve for the

transformer. Oil level is deemed to

be normal when its difference is

within one graduation of the gauge

on the curve.

(2) in bushing Check the oil level and oil leakage

on all oil-filled bushings.

When the indicated oil level is

constant with the changing oil

temperature, inspect the dial gauge

and check the actual oil level.

If the oil level is abnormal, adjust it

according to instructions.

If the oil level shows low, in case of

rubber bag or diaphragm type,

damage of rubber bag or diaphragm

is suspected.

If oil level of OLTC is abnormal,

breaking of seal between OLTC and

transformer is suspected.

3 Oil leaks Check oil leaks visually from

radiators flanges, pipes,

transformer tank and so on.

If oil leaks are due to gasket, tighten

bolts or exchange gasket.

In case of oil leaks from welded

parts, apply adhesive material or

weld again on the leaking part.


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TD-TSP-0004-2A (5/19)

No. Items Method Action

Abnormal or unusual noise,

especially from oil pump motors and

fan motors, should be carefully

listened to.

When oil pump or fan motor is

getting noisier, exchange the

bearings with new ones.

4 Abnormal noise

and vibration

Abnormal vibration can be checked

comparatively easily by hand.

When any supporters, pipes and

other parts are vibrating due to loose

bolts, tighten them.

5 Silica gel breather Check the breathing action in oil pot

and discoloration of silica gel

visually. Check the color of oil in oil

pot.

If the breathing action is not

satisfactory, check choking such as

filter in oil pot.

If the color of silica gel became to

pink from blue (or became to dark

green from orange) from upper sidecheck air leaks and fix it up.

If the oil color in oil pot blackened,

replace with new oil.

6 Gas trapped in

buchholz relay

Check whether any gas trapped in

buchholz relay with telescope.

If any gas trapped in the relay, the

transformer should be stopped for

investigation including accumulated

gas analysis.

7(1)Appearance

Bolt connection

Check any looseness of bolt

connection visually.

When any loose bolts are found,

tighten them.

(2) Discoloration Check visually that all connections

are normal without any

discoloration due to local heating.

When any connections show signs

of having been hot, clean and tighten

bolts and nuts.

(3) Dust Inspect visually for dust, especially

on radiators.

Clean up dust if it may reduce

cooling capacity of radiators.

(4) Rust Inspect visually for rust, especially

on radiators.

Re-painting is recommendable once

every five years.

Anti-rust and final paint should be

applied after rubbing off rust and old

paint.

(5) Dew Inspect visually for dew in the

terminal box, control cabinets and

protective relays.

If any dew is found, dry it out, and

ensure space heaters are in use if

they are provided.

NoteIn case of a self-cooled transformer, there is some difference between top and average oil

temperatures depending on loading conditions and ambient temperature. Strictly speaking, the

average oil temperature should be referred to for checking oil level.


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TD-TSP-0004-2A (6/19)

3.2 Periodical inspection

The recommended inspection frequency is described in parenthesis under each inspection item.

Table 2


1 Breather silica gel

(Once every six

months)

Check the discoloration of silica gel in

breather due to moisture in breathed

air.

If the color of silica gel has turned to

pink from blue (or turned to dark

green from orange) by more than

two thirds of total quantity, dry out or

exchange it.

If the color of silica gel has turned to

pink by more than two thirds of total

quantity, dry out or exchange it.

Insulation oil

Dielectric strength

(Every one year)

Measure dielectric strength with an oil

tester and confirm it is more than 40

kV/2.5 mm gap.

If any measured values are not

satisfactory, filtering and/or

degassing of insulating oil are

recommended. The permissible

value of OLTC oil shows in Table

4-b.

Moisture content in

oil

(Every one year)

Measure moisture content in oil with

Automatic Coulometric Karl-Fischer

Titration method and confirm that it issatisfactory to the criteria. Criteria of

OLTC oil is show in Table 4-b.

(Criteria of Transformer oil)

TR. Voltage 69kV > 69kV~230kV

M. Content 35 ppm 25 ppm

TR. Voltage > 345 kV

M. Content 20 ppm

2(1)

(2)

(3)

Acid value

(Every one year)

Measure acid value and judge it with

the criteria of Table 7.

(1) Measure insulation resistance of

fan motors and/or oil pump motors

with a 500V megger.

If insulation resistance is less than

2M, check balancing of load

currents of three phase and dry out

the interior of fan motors.

3 Fan motors and/or

oil pump motors

(At least once every

two years)

(2) Check if temperature rise of oil

pump motors cases, based on oil

temperature, is less than 10 deg. C.

If it is more than 10 deg. C, check its

insulation resistance, winding

resistance and three phase

balancing of load current.


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TD-TSP-0004-2A (7/19)


4 In case ofCooler

of water-cooled

type

(At least once every

two years)

(1) Analyze the characteristics of

cooling water as shown in Table 8.

(2) Check scale deposit on the inside

of the cooling tube to reduce the

water flow required, resulting in

excessive heating of a transformer

at normal load.

If any characteristics are not

satisfactory according to the criteria

shown in Table 8, shorten inspection

interval of coolers. If any heavy

scale is found on the inside of the

cooling tubes, clean them up.

(1) Check the water-tightness of a

control cabinet and a terminal box.

If the rubber gasket is worn out,

exchange it with a new one.

(2) Ascertain the tightness of all

control wiring connections.

Tighten the loose bolts.

(3) Operate all switches, annunciators

and lamps to observe proper

functions according to schematic

diagrams.

If any part maloperates, adjust or

exchange them with new one.

5 Control panel and

terminal box and

cables. (Once

every one year)

(4) Measure insulation resistance of

cable with 500V megger.

Check any crack or abrading on

cable insulation.

If such defect is found, put tape on it

or exchange it with new one.

Protective relays

(Once every twoyears)

(1) oil temperature indicator

(3) dial oil gauge(5) Buchholz relay

(7) sudden pressure relay

(9) pressure relief device

(2) winding temperature indicator

(4) oil flow indicator(6) gas detector

(8) differential pressure relay

(10) leak detector

Insulation

resistance

(Once every two

years)

Measure insulation resistance of

protective relays including their

wirings with a 500V megger.

When the insulation resistance is

less than 2M, check dews in the

terminal box.

6

(1)

(2)

Operation Operation tests should be made onlywhen protective relays operated even

if no troubles of a transformer

occurred.

The cause of a maloperation shouldbe investigated by operation tests

according to instruction books for

protective relays.

7 Connections

(Occasionally)

All connections outside of a

transformer should be inspected to

see whether they are in good

conditions without any discoloration,

which indicates hot connection.

Any connection that shows signs of

having been hot should be

thoroughly cleaned and bolted

together tightly.

for oil/watercooler


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TD-TSP-0004-2A (8/19)

3.3 Additional inspection

The following inspections and measurements are recommended for a preventive maintenance and ininvestigating a transformer trouble.For preventive maintenance, items 1 and 2 are recommended.

If a transformer was failed, all items (1 to 7) are recommended for the investigation on that particularoccasion.

Table 3

No. Items Method Action or remarks

1 Insulation oil

Analysis of gas

dissolved in oil

After a transformer is put into service,a periodic analysis of gas dissolvedin oil is recommended at least everysix months.

Using an appropriate airtightcontainer, oil should be taken fromthe transformer. The dissolved gasshould be extracted from the oil andanalyzed.

When the quantities of combustiblegases are obtained, evaluationscan be made to a probable locationand type of trouble, which may bepresent in a transformer.

(Refer to Table 10.)

2 Insulation resistance oftransformer windings

Measure the insulation resistancebetween a pair of windings, andbetween each winding and groundwith a 1,000 or 2,000 volt megger ata periodical inspection.

The megger test should be made tocheck if the transformer is in suitablecondition for operation or applicationof the dielectric test. Refer to Fig. 1.

The insulation resistance is subjectto wide variation with temperature,humidity and cleanness of bushingporcelains.

It may be low due to the leakagecurrent through the weakest pointof inferior insulation, in which casegases dissolved in oil should beanalyzed.

3 Ratio test Measure the ratio of a transformer bytwo voltmeter methods or with a ratiotester.

If the transformer has taps, the turnratio should be measured for all tapsas well as for the full winding.

The test voltage may be between 100and 200V at the rated frequency.

Compare the test results with thosein the test report.

If it is difficult to measure because

of fluctuation of voltmeter pointer orbecause of unbalance of a bridgecircuit, more detailed investigationshould be made.

4 Winding resistance Measure the winding resistance bybridge method or by drop-of-potentialmethod. If oil pumps are provided,they should be operated duringmeasuring winding resistance. Theoil temperature should be alsorecorded at the same time.

In case of low voltage and largecapacity delta winding (Ex. generatortransformer), there is a very difficultyto measure the winding resistanceprecisely and needs to pay carefulconsideration for judgment.

If the winding resistance, correctedto a specified temperature, isdifferent from the data obtainedpreviously, more detailedinvestigation should be made.

5 Excitation current at lowvoltage

Measure the excitation current at lowvoltage (100-200 volts) applied onthe lower voltage winding with otherwindings being open-circuited.

The voltage wave shape should besinusoidal.

Note (1)

If the measured excitation current ismuch larger than the original dataat installation, more detailedinvestigation should be made.

Note (2)


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TD-TSP-0004-2A (9/19)

No. Items Method Action or remarks

6 Impedance voltage Measure the impedance voltage atlow current (5-10 amperes) appliedon the higher voltage winding withlower voltage winding beingshort-circuited.

Note (3)

If the measured impedance voltageis much different from the originaldata at installation, more detailedinvestigation should be made.

7 Bushing currenttransformer

Excitation current and windingresistance should be measured in thesame way as items 4 and 5.

Same as above 4 and 5.

Note(1) The ammeter should be connected inside of voltmeter as shown below to avoid error due to high

impedance measurement.

(2) If the measured values satisfy an expression below, the transformer may not get serious injury such aslayer shorting.

10/IV

/IV

RR

MM

IRRated current

IMMeasured current

VRRated voltage

VMMeasured voltage

(3) The shorting cable should be more than 100mm2

in its section and be as shorter as possible in its length,to avoid measuring error.

(4) If those characteristic values from the item 2 to 6 are abnormally different compared the data withoriginal data, it is recommended to carry out an internal inspection. In this case, you are kindlyrequested to tell us the information as APPENDIX II.

TR

Shorting cable


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TD-TSP-0004-2A (10/19)

4. MAINTENANCE

Maintenance of parts and materials should be planned according to the following Table 4-a.

Table 4-a

No. Material and parts Maintenance frequency Remarks

1 Grease of fan motors Grease them up once a year, withthe grease gun.

Refer to item No.6. It is nonecessary when a bearing is sealedtype.

2 Porcelain insulator suchas bushing, lightningarrester, supportinginsulator

Cleaning should be doneperiodically.

Interval depends on actualcircumstance condition at site.

According to insulation book

Cooler

(1) Radiator type

Recommended cleaning frequencyis once every two years.

(2) Forced air type Dust and other foreign materials,

accumulated on the finned area,should be blown out to maintain theefficiency of the cooler.

3

(3) Water cooled type Internal compartment check andcleaning should be done once everytwo years.

With compressed air and/or water.

4 Paint for transformerexternal tank

Repainting should be done onceevery five years.

5 Bursting plate oftransformer

Bursting plate is recommended to bereplaced once every five years.

6 Bearing of fan motors

and oil pump motors

Expected life is ten years.

Expected life is three years, whenbearing is sealed type. (only fanmotors)

Exchange with new ones, if a motor

becomes noisy due to brokenbearings.

(1) Gasket

(Cork-neoprene)

(2) Thermometer

(Oil, winding)

(3) Pressure relay

(Water, nitrogen,sudden pressure relay,water/oil differential

pressure relay)

Expected life is ten years. Exchange with new gaskets, if oilleaks from gasket are serious.

7

(4) Rubber bag ordiaphragm inconservator

Expected life is 15 years. If any damage of rubber bag ordiaphragm is suspected, exchangewith new one.

8 De-energized tapchanger

Operate de-energized tap changermore than once a year when thetransformer is out of service

Internal inspection isrecommendable before operation ofthe de-energized tap changer, if thede-energized tap changer is notoperated more than one year.

Note: As for maintenance of on-load tap changers, please refer to the corresponding insulation books.


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TD-TSP-0004-2A (11/19)

OLTC diverter oil should be maintained according to Table 4-b.

Table 4-b

Permissible value

Location of on-load tap changer

Breakdown voltage Water content

Installed to line side

including delta winding40 kV/2.5 mm gap 30 ppm

Installed to neutral side 30 kV/2.5 mm gap 40 ppm


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TD-TSP-0004-2A (12/19)

5. TROUBLE SHOOTING

5.1 Diagnosis of protective relays in operationIf any protective relay gives an alarm, investigate its causes according to the following Table 5.

Table 5

No Relay Function Cause and Action

1 Dial type thermometer The dial type thermometer indicates

the top oil temperature and highest

oil temperature experienced. It gives

an alarm when oil temperature gets

to the alarm setting (80 for

example).

2 Thermal relay for oil

temperature or winding

temperature

The thermal relay detects and

indicates maximum oil or winding

temperature of a transformer.

It also has protective functions to

give an alarm or tripping signal, and

automatic functions to control

cooling system.

1.Overloading

2. Insufficient efficiency of cooler

units due to dust and other

foreign materials accumulated

on the finned area or due to a

heavy scale in the water-cooling

coils.

3. Maloperation of thermometer orthermal relay due to their own

defects.

4. If indication of thermometer is

not correct, check oil level in the

sensor pocket and adjust to

correct oil level.

3 Oil flow indicator The magnetic oil flow indicator

checks the operating condition of anoil pump. When an oil pump stops,

the pointer returns to the stop

position and the micro-switch

contact closes to give an alarm.

1.Trouble of oil pump motor

2.Trouble of wiring connection tooil pump motor

3. Radiator valves are shut off.

4. Inverse of power phasesequence.

4 Oil level gauge-dial type The dial type oil level gauge

indicates the oil level in a

conservator of an oil-immersed

transformer.

When the oil level comes down to

the bottom of a conservator, its

pointer indicates zero and give an

alarm.

1.Shortage of oil

2.Abnormally low ambienttemperature in winter season

3.Oil leakage

4. Damage of rubber bag ordiaphragm in conservator.

5. If oil level of OLTC is abnormal,breaking of seal between theOLTC and transformer issuspected.


13/19

TD-TSP-0004-2A (13/19)

5.2 Relay function

If any protective relay operates, investigate the cause of a trouble according to the following relaysfunctions.First of all, dissolved gas analysis is recommended immediately for the diagnosis of the transformer.

Table 6

No Relay Function and investigation

Buchholz relay

(1) First stage

The first stage of a Buchholz relay detects the gas formation due to minortroubles in transformer tank.

Rubber bag or diaphragm type conservator;

Stop operation of the transformer immediately, and carry out gas analysisof accumulated gas and dissolved gas in oil and internal inspection of thetransformer because a local heating and/or arc discharge is suspected.

Breather type and/or nitrogen gas sealed type conservator;

Check if abnormal gas are exist or not by gas analysis of the transformergas and dissolved gas in oil.

As the result, if abnormal gas are detected, stop operation of thetransformer and carry out of internal inspection.

The type and location of trouble may be predicted by gas analyses of oil.

Note: Nitrogen gas dissolved in oil could supersaturate and accumulate inthe relay and actuate the relay when oil-temperature drops rapidlyon a cold day in case of a gas-sealed transformer.

1

(2)Second stage The second stage of a Buchholz relay detects the rushing oil due to aserious trouble in the transformer tank.

If other protective relays, such as over-current relay of differential relayoperate at the same time, a serious internal damage is suspected.

2 Sudden oil pressurerelay

The sudden oil pressure relay detects the high rate of oil pressureincrease in a transformer tank due to the gas generation and oil vapourcaused by serious troubles. In case of correct operation, the transformer

operation should be stopped.3 Sudden pressure relay [In case of nitrogen sealed conservator]

The sudden pressure relay detects the high rate of nitrogen pressureincrease in a tank due to the gas generation and oil vapour caused byserious troubles in the transformer tank.

4 Pressure relief device The pressure relief device operates when the pressure in the relief ventrises abnormally high enough to reach the pressure of approximately0.7kg/cm

2caused by serious failure in a transformer.

It also operates when the pipe of air breather is choked so as to increasethe pressure in the relief vent.

6 OLTC protective relay OLTC protective relay detects some faults in diverter of on-load tapchanger.

Check the following items;

1.Fault of diverter insert

2.Fault of whole of OLTC

Malfunction of OLTC relay due to normal deterioration.

7 Differential relay The differential relay detects the difference between the input current andthe output current of a transformer converted by a current transformer.

It also operates sometimes with the inrush current when a transformer isexcited.

8 Over current relay andground fault relay

These relays detect faults in the electrical system including transformers.


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TD-TSP-0004-2A (14/19)

100 120806040200

2

3

4

6

8

10

15

20

30

40

60

80

100

150

200

300

400

600

800

1000

1200

Transformer oil temperature (C)

Insulationresistance(Megohms)

good

poor

System voltage more than 6kV

Systme voltage more than 11kV



Fig1. Allowable value of transformer insulation resistance


15/19

TD-TSP-0004-2A (15/19)

Fig2. Relation between dielectric strength and amount of water in insulating oil

Table 7. Acid value criteria

No Acid value (mg KOH/g) Action

1 Less than 0.2 Good

2 From 0.2 to 0.4 in earlier stage

3 More than 0.4

Filter or exchange

with new oil. immediately

Table 8. Criteria of cooling water characteristics

No Test item Criteria

1 Hydrogen ion concentration (PH) 6.0 8.0 at 25C

2 Electrical conductivity Less than 500 (/cm) at 25C

3 Chlorine ion (C1

) Less than 100 ppm

4 Total hardness (CaCO3) Less than 150 ppm

5 Sulfuric acid ion (SO4 ) Less than 200 ppm

6 M-Alkalinity (CaCO3) 15 60 ppm

7 Sulfur ion (S

) undetectable

8 Ammonium ion (NH4+

) undetectable

9 Total iron ion (Fe+++

) Less than 0.5 ppm

10 Silica (SiO2) Less than 30 ppm

Table 9-aResistivity criteria of insulation oil, at 80

50

40

30

20

10

020 30 40 50 600 10

Water-parts per million by weight (PPM)

Dielectricstrength(kV)

2.5

mm

gap/12.5

mm

sphe

re


16/19


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TD-TSP-0004-2A (17/19)

Table11. Combustible gas levels for maintenance

GasesThe level needed a

follow-up surveyPermissible levels

C2H2 0.5ppm 5ppm

H2 400ppm

C2H4 100ppm

It should be evaluated by necessary and sufficient

conditions with the following two items.

C2H4more than 100ppm

TCGmore than 700ppm

CO 300ppm


conditions with the following two items.

COmore than 300ppm

Ratio of CO2/CO

Normal ratio is more than 3

Abnormal ratio is less than 3

TCG

(Total Combustible Gas)700ppm


conditions with the following three items.

Increasing rage70ppm/month of TCG

C2H4100ppm

TCG700ppm

APPENDIX I Actions for safety and quality


18/19

TD-TSP-0004-2A (18/19)

Table 11

No Working condition Actions for safety

1 Exterior check (1) Be careful not to approach live parts.

2 Electrical test and

remedial work

(1) De-energize the transformer by circuit breakers and line switches.

(2) Ground the line terminals of the transformer.

(3) Attach caution tags not to operate switches for circuit breakers and line

switches. See note.

(4) De-energize the control cabinets for coolers and tap changer by AC and DC

switches.

(5) Attach caution tags on switch boxes.

3 When internal

inspection is to be

made

Same as above except the following additional items.

(1) Replace nitrogen gas completely with dry fresh air, if it was filled in the

transformer.

(2) Make sure there is 18% or more oxygen to sustain life in a transformer

tank.

(3) Make sure your pockets are empty.

(4) Take off a wrist watch and any other accessories on your body.

(5) List up name and quantity of all tools to be brought into a transformer

tank.

(6) Spread out clean cloth on coil groups when repairing.

(7) Protect lamps with guards not to break them in a tank.

(8) Be careful not to drop any tool and foreign material into the transformer.

Secure all tools with hand lines. Any metallic item dropped into a

transformer must be removed to prevent serious trouble in future.

4 After inspection

work

(1) Make sure all foreign materials are clear before closing manhole and

energizing.

(2) Check the quantity of all tools brought out from a tank.

(3) Remove the grounding wires on the line terminals of the transformer.

NoteWhen test and remedial work must be carried out under the live conditions for any special reasons, pay

attention to live parts to protect yourself against electrical shock.


19/19

TD-TSP-0004-2A (19/19)

APPENDIX II Technical information to be sent to the manufacturer

Whenever you need technical advice for any troubles of parts and/or a transformer itself from Shihlin Electric

Corporation, you are kindly requested to let us know the following technical information.

(1) Name of the power station or sub-station where the transformer is in service

(2) Serial number and ratings of the transformer in trouble

(3) Name, type and serial number of the parts in trouble

(4) Detailed explanation in case of more severe troubles

a. Duration and amperes of over current

b. Overvoltage and/or surge applied on the transformerc. Protective relays in operation

d. Load conditions (voltage, current and power factor)

e. Copies of p/s or s/s layout drawings which show location of the transformer and other electrical

equipment such as circuit-breakers, lightning arresters and line switches

f. Copies of skeleton sequence drawings for control panels

(5) Any other information available about the trouble

Your quick and detailed information is being expected, which would result in quick and more appropriate

actions for its recovery.

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