Maintenance Manuals

1ZVN460100 – D Maintenance Manuals

1ZVN460100 – D 2 / 3

Table of contents 1 Maintenance...... 3 2 Trouble Shooting ...... 5

1ZVN460100-D

1. Maintenance:

Subject Check Time period Remarks Year Month

Insulating oil Dielectric strength 3 Moisture content 1 Neutralisation value 1

Interfacial surface tension 1

Water content 1 Sludge content 1

Gas analysis 1 Oil tightness Tank 3 Conservator 3 Cooling equipment 3 Piping 3 Bushings 3

Cable sealing ends 3 If applicable

Cable boxes 3 If applicable Buchholz relay 3 Gate valves 3 Valves 3 Oil level Tank 1 Conservator 1

Bushings 1 Cable sealing ends 1 If applicable Cable boxes 1 If applicable

Thermometer pockets 1 Venting devices Tank 1 Release vent screws until Cooling equipment 1 Oil emerges. Afterwards Intermediate piping 1 screw plugs tight Bushings 1 Piping 1

Buchholz relay 1

Cable sealing ends 1 If applicable Earthing devices All metal parts 1 Tank 1 Motors 1 Star points 1 If applicable Surge arresters 1 If applicable Control cabinet 1 Steal armoured cabling 1 Shut-off devices In position “service” As required See plan “Position of shut off devices” (if provided) Buchholz relay Direction of oil flow At erection Float 1 Contacts 1 Gas sampling device 1 If applicable Functional test 1 Dial-type thermometers Contact setting 1 See the Technical data Position of maximum pointer 1 Functional test 1 Current transformers Polarity At errection Ratio At errection Short-circuit connection 1

1ZVN460100-D 4/9

Subject Check Time period Remarks

Year Month Oil level indicator Contact setting 1 At errection Float 1 Functional test 1 Breather Silicagel 3 Oil level 3 Venting pipes 3 Internal wiring Insulation resistance 3 With 1000V Megger Tester, Correct wiring connection 3 Values 50 Mö Corrosion protection Paint 3 Touch-up Blank steal parts 3 Grease Cleanness Bushings 3 Fittings 3 Indicating devices 3 Tank cover 3 Remove loose parts, Fans 3 If applicable Control cabinet Connection 1

On-load tap changer See instruction of the

manufacture Switching over all positions Off-circuit tap changer N/A

(at least 25 x) to clean

contacts that may be oxidated

and to prevent gas formation

that may result in flash-over Cooling equipment 1 See instruction of the Supervisory equipment for 3 manufacturer cooling equipment Protective relay for OLTC See instruction of manufacturer Thermostat Functional test 3 Resistance thermometer Functional test 3 Pressure relief device Functional test 3

1ZVN460100-D 5/9

2. Trouble shooting

Protective Fault Possible cause Remedial measure Detailed and description supervisory instruments Various components Buchholz relay Alarm at - Oil loss Operation can be continued Buchholz - Accumulation The following tests and examinations for fault analysis relay of air Should be made as soon as possible - Gas generation 1. Check oil level, pipes, position of valves

due to inside 2. Check the electrical connections

failure 3. Check the tripping mechanism of the Buchholz relay

- Violant 4. Put part of the gas into a glass container within five vibration hours and analyze it.

- Fault tripping 5. Evaluate the gas analysis 6. Take oil sample (1 litre) from tank top and make and make a gas analysis 7. Take oil sample (1 litre) from tank bottom and check for dielectric strength (VDE) 8. Undo all bushing connections and make the

following measurements:

8..1 Measure the insulation resistance between the windings themselves.

Rough guide value: 1MΩ per kV rated voltage

8.2 Ratio measurement either with measuring kit or by applying low voltage to the HV side 8.3 Measure the winding resistance with DC 8.4 Measure the no-load current by applying low voltage 9. Compare the result with the test certificates of the operating instructions

Vent the transformer and put it back into operation

when faults cannot be found or faults have been eliminated. If the fault occurs frequently, contact

ABB.

Buchholz relay Buchholz - Oil loss - Maintain the shutdown status. relay - Violent oil - Carry out tests and measurements as described under tripping surge due to points 1 to 9 inside flashover - Vent the transformer and put in back into operation - Violent gas when faults can not be found or faults have been

generation due eliminated

to inside failure - Violent vibratio

- Fault tripping Protective Tripping - Maintain the shutdown status Instruction of device for due to - Check the tripping mechanism OLTC OLTC strong oil - Remove and check the diverter switch surge - Reset the tripping mechanism and put the transformer into operation

1ZV460100-D 6/9

Protective Fault Possible cause Remedial measure Detailed and description supervisory instruments Various components - Resistance Oil temp. - Transformer - Reduce load of the transformer Operation thermometer too high overloaded or - Put fans or cooling equipment in service Instruction of - Thermostat inadequate - Clean the cooling equipment thermometer - Dial type Wdg or cooling - Check the position of butterfly valves manufacture thermometer oil temp. - Incorrect temp. - Adjust incorrect temperature setting for oil or wdg too high adjustment - Check the thermometer by comparative temperature measurements indicators - Check the electrical connections and the tripping mechanism

- Check control devices for cooling equipment - Check current transformers and thermometers Oil level Oil level Not enough oil - Check for tightness Operation indicator too low (low temperature - Top-up oil instruction of or oil loss) manufacturer Oil flow No oil monitor flow Water flow No water N/A

monitor flow

Redused

water

flow Pressure relief Internal - Conservator - Check the pipes and shut-off devices Operation device tank pipe shut-off or - Check the transformer as described in “Buchholz instruction of pressure clogged. relay” (point 1-8) manufacturer too high - Electric flashover inside the tank Motor drive Drive - No voltage - Check supply feeders Operation for OLTC can not supply at motor instruction of be protective OLTC operated switch (MPS) electrical - MPS not in - Close motor protective switch oper. Position - Motor - Check supply feeders and contactors and replace

contactor K1 or If necessary

K2 does not Pick up

- Motor

contactor K1 or

K2 stuck - Brake contactor - Check contactor, clean or replace if necessary - K3 does not pick up - Open circuit on - Correct it

one or more

motor phases Moto drive for Drive - Brake contactor - Clean or replace OLTC keeps on - K3 stuck running

1ZVN460100-D 7/9

Protective Fault Possible cause Remedial measure Detailed and description supervisory instruments Various components Motor drive Motor - Emergency - Repair or replace emergency stop button for OLTC protectiv stop - Check drive for stiffness with cran handle. Request a switch button is on or factory engineer, if a mechanical fault in the tap- trips stuck changer is suspected during - Motor current operatio excessive due of motor to overload or

drive phase failure

Off-circuit tap Operatio N/A changer not possible

Dehydrating The - High atmosph. - Replace dehydrating agent breather drying humidity, glass - Replace glass cylinder or seal properly cristals cylinder leaky - Seal pipe leaks, check the oil for moisture content. turn from - Moisture in - Flush the conservator with dry air blue to conservator, pink and pipe leaky, then to glass cylinder

white leaky. from - Glass cylinder

below, burst,

maintenace from top, interval

in general

Electrical Breakd. - Breather - Put breather into operation breakdown voltage inoperable or voltage of the too low. trafo in service oil very low

Water - Leaks in water - Seal or repair coolers content cool. System too high - Water pressure - Contact manufacturer; dry the oil, if necessary

reducer

inoperable. Protective Frequent N/A spark gap on operatio bushings Terminal lugs Discolo- Check surface contact on bushing ration of connect- ing parts

1ZVN460100-D 8/9

Protective Fault Possible cause Remedial measure Detailed and description supervisory instruments Various components Control cabinet El. App. - Excessive - Set the cabinet heater to a higher temperature does not humidity in operate control cabinet - Seal the cabinet door, fit a dust filter if necessary properly - Water or dust - Protect the cabinet against solar irradiation; provide Contacts inside the for better ventilation corroded cabin. or conta- minated - Excessive high temp. in the App. cabinet housing bent Earthing Earthing - Excessive - Clean the contacts, tighten the screws and check the connection line current due to Electrical distances. Open up current loops. Only innterupt external flash one earthing with a sufficient cross section. -ted - Impermissible current loops through

multiple earthig Pressure gauge Oil - Incorrect - Correct the contact adjustment for HV pressure contacts adjust. bushing in HV - Check the reading bushing - Bushing too high overloaded, oil - Check the bushing; reduce the transformer load, temp. too high increase the cooling effect due to solar irradiation Pressure Oil - Incorrect - Correct the contact adjustment monitor for pressure contact adjustm HV bushing in HV - Check the pressure monitor and reset the auxiliary bushing - Bushing switch too high overloaded, oil temp. too high - Check the bushings; reduce the transformer load; due to solar increase the cooling irradiation.

- Violent vibratio

on transformer Air flow No air monitor flow or reduced air flow Oil sightpot Traces of oil on the water surface

Document Title Maintenance Manual

Document No. Date & Rev. Ind. No. of Pages Page 1ZVN460100-D 1 9 9