Oil Immersed Transformer Installation & Operation Manual

Publish time: 2021-03-17 13:58:00 View: 3265

Oil-immersed Power Transformer Installation and Operation Manual

1.General rules

1.1 The instruction manual applies to the low-loss oil-immersed power transformers with the capacity up to 6300KVA.

1.2 The using conditions for transformer are according to the regulations of OBT.500.1200 and OBY.500.507, the climatic conditions and corresponding max temperature rise of the oil level in using district as follows:

Use District

Max Ambient Temperature

Relative Air Humidity

Max. Temperature Rise

Temperate Zone


Not Exceed 90% when +25℃




2.1 The transformers that the capacity is below 2500 KVA, should be transported filling with oil, and no need to remove the bushing and conservator. But for which the power is 2500kVA or above, in the transit, the oil level should be dropped to 100mm of tank cap, meanwhile, the conservator and radiator have to be removed. All of the removed parts, accessories, kit parts and tech-documents, shall be packed separately and delivered together with the transformer.

2.2 When lifting the transformer on transportation and installation, please use 4 lugs attached to the tank side at the meantime, which can support the total weight of the transformer. The lifting board on tank cover is only used to lift the transformer body. Please be noted that the angle between lifting rope and vertical line shall not be larger than 30°. Otherwise, please lift the transformer by special middle beam.

2.3 The inclining angle of the transformer during transportation is allowed not to exceed 15°. Do not move previous so that the transformers will not to be shocked, jolted and stroked.


3. Examination & Acceptance and Storage

3.1 User should check from the nameplate to see the model and specifications are conform to the order contract, as well as the tech-documents and accessories are completed.

3.2 Examine the appearance of the transformer:

1) Whether the oil is leaking or seeping

2) Whether the accessories are damaged.

3) Whether the damageable parts are free from damage, such as bushing, fuel level gauge, dehydrating breather, signal thermometer, gas relay and etc. (For which the power is 800KVA and above should have a gas relay, for which the power is 1000 KVA and above should have the outdoor signal thermometer.)

3.3 If the transformer is not installed immediately and need to store, the oil level shall always keep above the tank cover, meanwhile should check periodically the storage conditions. For the transformer that is transported with conservator removing, we must to fit on conservator promptly when arrival whether or not it is put into operation, and pour into the qualified oil up to the oil level line to ensure there is enough oil and pressure in the tank, so as to meet the needs of the temperature change.


4. Transformer Inspection

4.1 This series of transformers, we have taken measures to avoid the fasteners loosen and relative displacement of the body in transportation. So, it is generally no need to lift the core for checking, unless there are damages or serious tank leaking during the transportation.

4.2 It is generally to lift core indoor, where should be clean and dry. What’s more, when it has to be checked outdoor, we must strictly prevent the dust and sudden downpour.

4.3 The core hanging must under a condition of the transformer temperature (measured on upper yoke) is not lower than the ambient temperature. Unless, we should delay the hanging time, and take appropriate measures to increase the transformer temperature, in order to avoid the transformer affected with damp that caused by the moisture in the air condensed in the body.

4.4 It is only allowed to lift the core indoor on rainy day or greasy day, by this time, the temperature indoor is requested 10℃ higher than outdoor.

4.5 The time stay in the air of the transformer shall not exceed the following stipulations:

Do not exceed 16 hours in case of the RH max. 65% in dry weather Do not exceed 12 hours in case of the RH max.75% in wet weather.

4.6 Transformer body inspections:

1) To eliminate all the faults and damages have been found in checking, and should pay special attention to coil compression and leads supporting & clamping situation. If there is any looseness, deflection and other defects such as collision, should be repaired carefully.

2) Checking the bolts on each part of the body, and should be tightened if there is any looseness.

3) Measuring the earthed insulation resistance of the coil and checking the grounding of iron core.

4) Checking the tap-changer connection and measuring the dc resistance of coils in each tapping position.


5. General Assembly

5.1 Well install the radiator, conservator, signal thermometer, gas relay and mercurial thermometer (prepared by user) which removed in transportation. Please as per the Operation Instructions Manual for all of the attachments.

5.2 Fill the qualified oil to all of the attachments that should be oiled. For the transformers which equipped with radiator, gas relay and the bushing, we should open the radiator bottom valve first when filled with oil and then open the upper valve, afterwards, turn on the air relief plugs quickly and lightly to release the air. After 24 hours, check if there is any oil leaking, and then release the gas in gas relay again. When fill the transformer oil, please pay attention to the model and origin of the oil, generally, the different model cannot be mixed except it is passed the tests.

5.3 To do the sealing test after oiled.

Using oil plug on conservator, replenished with 0.25kg/cm2 dry and clean compressed air to do the static pressure test, keep 3 hours without tank leaking.

Attentions for sealing test:

1)    Fill transformer oil in bushings.

2)    Release the gas in gas relay

3)    For the transformer with OLTC, shall watch if the oil level in switch is raised or not in the process of forcing. If it is raised, then the switch may be oil leakage, and should inform the factory.

5.4 For the transformer equipped with gas relay, one end of the tank with gas relay should be padded 10-15mm higher after installation, to make the transformer tilted slightly, so as to increase the action sensitivity of the gas relay.


6. Preparation before Running

6.1 After the final assembly, it should be tested as following before running:

1) After 12 hours when filled with transformer oil, take the sample from the valve for breakdown voltage testing.

2) Measuring the insulation resistance.

3) Measuring the coil dc resistance for all of the tapping position. The difference for the dc resistance value and factory value shall not exceed ±2%.

4) Checking the voltage ratio and voltage vector for all of the tapping position.

5) Testing for applied power-frequency high voltage. The testing voltage is selected from the hand-over test standard, take 1minute.

6) Using max.110% rated voltage to do the no-load testing, take 30seconds. Pay attention to the changing for noise and instrument.

7) Measuring the no-load current and no-load loss. The results should have no significant different with the factory testing results (as per the testing values on instructions).

All the tests above shall be performed at least 10hours after filling with the transformer oil. And keep the testing sequence.

6.2 After finishing all of the above tests, it shall be inspected as follows:

1) Setting and experimental protection device, such as the actions of gas relay, over-current relay, and differential relay.

2) Checking the actions of transmission mechanism and interlocking device of oil short circuit.

3) Checking the oil level in conservator, the connecting valve between conservator and oil tank must be opened

4) Checking the two valves (top & bottom) on radiator are both opened.

5) Checking the thermometer reading is correct.

6) Checking everywhere and ensure there are no irrelevant things on transformer.

7) Checking the oil tank is well earthed.

6.3 For the transformers equipped with Buchholz relay, should turn the signal contact to the transformer power tripping circuit first, and set the over current protection delay as an instantaneous action, then join up the rated voltage, lasts 30minutes, and listen the noise.

6.4 Power cut after finish the testing, resetting the over current value, connect the signal contact to alarm circuit, and connect the tripping contact to trip circuit, and then no-load switching-in 3-5 times under the rated voltage for checking the gas relay protection device under the action of the excitation current shock.

6.5 If the test result of input voltage is good, it’s OK to put on load for running.

6.6 Before put into operation after final assembly, if there are any other testing items please as per the transformer operation regulation issued by water and electricity dept.


7. Operation and Maintenance

7.1 Rated operation mode

1) Transformers can be operated as per the nameplate in the specified cooling conditions.

2) The allowed temperature in running of oil-immersed power transformer can be checked by the top oil and its value should abide by the provisions of the factory, the highest oil temperature shall not exceed 90℃.

3) The transformer can be in continuously running under the rated capacity and maximum voltage does not exceed 5% of the corresponding tapping voltage.

7.2 Allowed overload

1) The transformer can be operated in the conditions of normal overload and accident overload. Normal overload can be often used, its value is decided by the transformer load curve, the temperature of the cooling medium and the load before overload.

Accident overload is only allowed to use in accident cases, for example, in case of one set is damaged in the several sets of transformers in running, but there is no standby one, then the rest of transformers are allowed to process as an accident overload. The allowed value as per

table 1-2

The ratio of accident overload to rated load






Allowed overload lasts time (minutes)






2) Allowed short-circuit current and unbalance current:

a. The short-circuit current of the transformer shall not exceed 25times of the current, the time of the short-circuit current passes through t shall not exceed the value listed by the following table 1-3

Table 1-3


above 20


below 15

T (seconds)




P.S.: K in above table is shown the times between steady short-circuit current to rated current.

b. For the transformers that the connection is YynO,the midline point current shall not exceed the 25% of LV rated current.

7.3 The regular maintenance of transformer:

1) During the operation, please often check the temperature indicating device and oil level indicating device and other protective devices, such as gas relay, etc., to ensure the reliable actions. And also, often check if there is any oil leaking in each flange and the seal.

2) It is better to do an oil sampling test every six months (at least once a year). If the moisture is rising continually and contains impurities and sediments in oil, then should do a voltage withstand test for filtration. Besides, if the insulation performance of oil is reduced too much, shall check for any fault’s interior the transformer. In case of the oil temperature increased abruptly under the normal load and cannot eliminate the fault, must stop running, and then hanging out the body for checking, so as to find out problems for repairing in time.

3) Stop running for checking in case of any abnormal noises and oil level instability, even the glass of safety airway is blasting and conservator oil leaking seriously causing the oil level lower than the limit on oil meter.

4) If a transformer always amounts of load or short-circuit, then should hanging out the core for checking once a year.

5) For the transformers equipped with gas relay, when the gas relay sends signals, if it is not caused by the external reasons such as the air intrusion or oil level reducing, etc., should quickly identify the gas nature, if it is flammable, then must stop running the transformer at once until troubleshooting and passing inspection.

6) Other maintenance requirements please as per the Transformer operation regulation issued by Water and Electricity Dept.


8. Power Transformer with OLTC Use Rules

8.1 Structural feature

1) For 10KV and 35KV power transformer with OLTC, there are 9 tap points and 8 tap points coming out respectively from the primary coil for connecting to the OLTC in corresponding position, when the grid voltage is fluctuated within a certain range, can switch the OLTC in loading cases, to change the primary coil turns for the purpose of regulating the secondly voltage.

2) The OLTC (as per on-load tap changer specifications) is placed on the oil tank along the long

axis and in the opposite direction of conservator, the switch is the resistance-type, the contact terminal is combined the selector switch and deliverer switch. The OLTC can be automatic control and operated by the automatic controller.

8.2 Notice

1) The OLTC do not guarantee the synchronous switching, so the transformer cannot be in parallel operation.

2) The transformer is allowed to over load according to the OBT 500 1200 of low-loss medium sized transformer technology conditions. In order to ensure the normal using life of the switch, should avoid the frequent operation.

3) When the transformer over-load exceeds 100% or short circuited, the primary side of relay protection device should guarantee the switch not to on-off, and cut off power supply.

4) In order to avoid the short-time over magnetic excitation when power restoration, thus leading to the damages of the electrical appliances while secondly voltage of a sudden increase. When the OLTC in the negative tapping position and loss of pressure, should take measures to make the switch instant reset to the rated tapping.

5) For the products that the voltage regulating ranges are in±4x2.5%(10KV grade) and ±3x2.5%(35KVgrade), should grantee to output the rated capacity when .negative tapping,

6) OLTC should in rated tap position when the transformer leave factory.

7) Before running the transformer, should operate the controller (electric & automatic), and do the 1-9 tapping cycling test for OCTL for checking the controller and switch matching and mechanical action is flexible and normal.

8.3 Maintenance & other considerations

1) Should always checking the oil level temperature and oil level in conservator & tap-changer in running, and filling the same type and qualified transformer oil timely.

2) In order to prevent lightning and over voltage to damage the transformer, it is suggested to install a lightning arrester on both up and down side of the transformer.

3)The oil in tap-changer must be replaced in case one of the following situations:

a. After 3000 times switch-over.

b. The oil breakdown voltage is lower than 25KV.

c. The oil flash point is lower than 125℃.

4) The on-load voltage regulating controller should be checked once every six months (including the insulation of the controller cable) for troubleshooting timely.

5) The OLTC should be maintained once for each 20000 times switch-over, the content and method as per the on-load tap changer specifications.

6) The controller cable replacement should according to the connection method shown in

on-load voltage regulating controller specifications, so as not to cause the mis operation by error link or other running accidents.

7) Other maintenance attentions are the same as the transformer with off-circuit tap-changer.


9. Agricultural Transformer Use Rules

9.1 The electromotor should be equipped by the rated capacity of transformer, please be noted that the 1KVA transformer is not equal to 1KW electromotor. By rough estimate that 1KVA transformer can be equipped with 0.7KW electromotor. Measuring the input current is conform with the rated current on nameplate when use the motor, and it cannot use if exceed.

9.2 Running the transformer frequently, and keep it clean. The Maintenance must be in a power failure, and pay special attention to the fragile parts such as porcelain bushing, oil indicator lamp and ect not to be damaged.

9.4 In the operation of transformer, should measuring the oil level temperature frequently(measured with a thermometer inserted into the socket on tank cover ), and ensure not to exceed 95℃, otherwise should make it down to the allowable value by lower the load operation. The allowed temperature rise of oil level is 55℃ (the temperature rise means the value that the temperature on the thermometer minus the ambient air temperature)

9.5 When the fuse is burned up due to the HV dropping of transmission line, should find out the reason first.

9.6 Must check the tap-changer position is correct before power transmission of transformer.


Non-excitation Tap-Changer Operation Manual


There is a non-excitation tap changer on transformer tank cover, for the use of conversion for high voltage side of the tap.


2.Structure & Operation

2.1 The number positionⅡon three gears tap-changer dial is shown the rated voltage,Ⅰshows the tapping point +5% of the rated voltage,  Ⅲshows the tapping point -5% of rated voltage.

The number position Ⅲ on five gears tap-changer dials shown the rated voltage, Ⅰ,Ⅱ,Ⅳ,Ⅴ respectively shows the tapping point +5%,+2.5%,-2.5%,-5% of the rated voltage

2.2 When operates the tap-changer, must cut-off the high voltage side line first to ensure without any power in transformer.

2.3 When transforms the position of tap-changer, must remove the drip-proof cap first, pull out the locating pieces from the dial locating slot, and then turn the handle to the required tap position, and make sure the handle locating piece can be normal placed in the relevant locating slot, well cover the drip-proof cap, then the transformer can be in operation.


3. Maintenance & Repair

3.1 Tap-changer should be maintained and repaired annually and pay attention to the followings:

1) Remove the drip-proof cap for checking the rusting in each part, and to wipe up, paint the right amount of grease.

2) Checking the position of each tap-changer lock, if there is any loose shall be tightened.

3) Checking the situation for each tap contact and damage. Rotate left and right the switch handle 10-15 times, it shall be fixed in the original position if the voltage is no change. But if the tapping position is changed, then should measure the access by bridge and multimeter for running. 3.2 Please note that the time to stay in the air for checking the tap position should not exceed the allowed time to stay in the air of transformer body which in the same insulation grade.

3.3 If oil leaking is found in the joint of tap-changer and tank cover or in the shaft of the tap-changer, shall slightly screw the mounting nut or gland nut of the tap-changer.



Below 35KV Transformer Bushing Operation Manual


The bushing is a piece which connect the inner coil outgoing line and outer circuit of transformer. Its voltage grade and the working current is determined by the value of rated voltage and rated current of the coil which connected with the bushing. The bushing is consisted by ceramic bush, conductive rod, nut, washer and other relevant parts. It has the reliable electrical performance and enough mechanical strength in structure, all of the sealing surface are well sealed by oil resistance rubber washer, to ensure the long-term normal operation of transformer.


2.Operation & Maintenance

2.1 Before each operation, must check the HV & LV bushing are in good condition as well as the sealing &cleaning condition.

2.2 The bushing should avoid the heavy impact and severe vibration, and should be replaced if there is any breakage crack.

2.3 The bushing surface shall always keep clean in transformer operati0n, to prevent the flashover discharge cause by coal dust accumulation (bushing cleaning should under the uncharged condition in both HV and LV side)

2.4 Is there is oil leaking in the seal, can tighten the gland nut in the relevant location. If the oil leaking is caused by the oil resistance rubber washer aging or metamorphism, and then shall replace the washer.

2.5 As a request of special needing or the porcelain damaged and have to remove and reinstall the bushing, please pay attention to the followings:

1) For a combined bushing, if the upper ceramic bush is damaged, it is permit to replace without lifting the core. But must pay special attention in installing to insert the conductive rod pin into the bottom bushing locating slot, to avoid the rotation. If the bottom ceramic bush is damaged, then should be replaced by lifting the transformer cover.

2) When inspecting and installing the bushings, should make the conductive rod and circuit well connected, but it cannot be overexertion when screw the nut, so as not to damage the conductive rod and the ceramic bush.

3) After maintenance and installation of the bushings with vent plug, should unscrew the upper vent plug, make sure to rule out the internal air completely.


Conservator Installation and Operation Manual

1.     Summary

The Conservator is a kind of oil protection device. In order to reduce the contact surface of transformer oil and air, prevent the oil quick dampening and oxidation, and also ensure the transformer body is submerged in the oil in any case. The oil-immersed transformers are usually equipped with conservator which volume is about 10% of the oil tank.


2. Usage & Structure

The Conservator can be divided into five sizes from the different diameter: φ180、φ250、φ 310、φ440、φ610

The conservator body is a circular container which is welded by thin steel plate, the weights of transformer oil and other accessories are supported by a brace which is welded by steel plate and steel angle, and fixed to the tank cover with bolt flatly.

Bend is worked to uniform the conservator and oil tank. For the conservators that the diameter is φ440 or above, will equip a gas repay (as per the Gas Relay Instructions) in the bend, and also equip a flat valve on the gas relay close to the conservator side, so that the conservator and oil tank can be separated when necessary. All of the conservators are open-type, the cover plate can be removed for cleaning.

Oil meter is used to indicate the height of oil level in the conservator. When the transformer in holding state, the height of oil level should on the scale line of the relevant temperature in oil meter.

All of the conservators will be equipped with a Dehydrating Breather(as per the instructions), for reducing moistures and dusts in the air that entering into the conservator when transformer “breathing”.

For conservator that the diameter is above φ440 will be equipped with a catch basin to precipitate the basin and moisture, and to weld a plug to the bottom of catch basin.

Plug on the bottom of conservator is used for oil dumping or sampling test when needs.

Plug on the top of conservator is used for oiling and degassing.

Outside the conservator wall will mark the type of the transformer oil.


Gas Relay Installation and Operation Manual


The Gas Relay is a kind of protection device for oil-immersed transformers equipped with conservator, it is installed in the pipe connector between transformer cover and conservator.


2. Structure & Working principle

The gas relay It shall full of transformer oil in operation. In case of the slight fault inside the transformer, it is due to the gas produced by the transformer oil decomposed gathers in upper gas chamber of the relay and forces the oil level to reduce, snap ring E reduces to a certain position together with it, and magnet D thereon makes dry reed contact R suck to connect with the signal circuit to give alarm signal. If there is a limit position inside transformer, magnet M thereon makes dry reed contact R suck to connect with the tripping circuit to give alarm signal and cut off the transformer.


3. Conditions of Use

3.1 Permissible operating temperatures: 30℃ to +95℃

3.2 Assembling method: the relay is pipe axis should be parallel to the transformer case cover, and is allowed for the end leading to the conservator is higher, however the inclination between the axis and level surface may not exceed 4%.

3.3 Rated Voltage: DC or AC 220V

3.4 Pipe diameter:Type QJR1R-50 is 50mm, Type QJR1R-80 is 80mm.


4. Performance Parameter

4.1 Gas volume for signal contact: 250-300m³。

4.2 Oil flow velocity for trip contact action:

Type QJR1R-50 is 0.6-1.0 m/s, factory setting 0.8m/s.

Type QJR1R-80 is 0.7-1.5 m/s, factory setting 1m/s.

4.3 Contact rated voltage: DC 220V 0.3A

4.4 Insulation strength as per table 2-3:

Table 2-3

Test item

Between each single contact terminals

Outlet terminal to earth

Between Signal and trip

contact terminals

Applied frequency voltage

2000V in one minute

2000V in one minute

2000V in one minute

4.5 Sealing Property: The Gas Relay is full of transformer oil, and pressurize 2.5kg/m²at normal temperature, no oil leaking for 20 minutes.

4.6 Shock resistance: When shock frequency (sine wave) is 4 to 20 Hz and acceleration is 4g, the gas relay is without fault action (g means gravitational acceleration)

4.7 Weight: around 10kg.


5. Installation & operation

5.1 The relay core must be taken out and the bandage is disassembled before installation. Check all of the fastenings if they become flexible, if the snap ring and guard board move flexibly, and if the contacts open and reliably.

5.2 Gas volume adjustment: one side of snap ring is installed a weight drop F, and the gas volume of signal contact can be adjusted by changing the position of weights drop for the range of 250-300 m³.

5.3 Oil speed adjustment: To lose the regulating rod Q and change the length of spring K, then the oil speed for the action of trip contact shall be adjusted.

5.4 Regulating rod N is used for adjusting the distance between magnet M and dry reed contact P (usually 0.5-1.0mm).

5.5 After checking and adjusting, please put in the relay core to the shell (the shell and core must be cleaned by transformer oil), and then install the gas relay in the pipe connector between transformer cover and conservator. Please pay special attention that the arrow on the relay must be directed to the conservator.

5.6 After finish installing, open the oil valve on the connecting pipe to oil the gas reply, and then open the air plug cap, unscrew the thimble to eliminate air until the vent T bleeding continuously.

5.7 Pump the air from T can check the reliability of the signal contact action.

5.8 Screw out the cap A, press the probe can check the reliability of the trip contact action.



6.1 When replace or add the magnet and dry reed contact, please note that all of these parts should be made by the non-magnetic material.

6.2 The magnet may not be vibrated acutely or put in strong magnetic field or an environment at temperature higher than 100℃ or lower than -40℃ to prevent from being demagnetized.

6.3 Do not disassemble the dry reed contact at will, especially do not bend the root of the lead to avoid from damaged.



Dehydrating Breather Installation and Operation Manual

1. Usage

Dehydrating Breather is used to filter the air that enters into conservator due to the oil temperature changing, and clean up the moisture and impurities. It is generally installed on the conservator.


2. Structure & Working principle

2.1 The main body of Dehydrating Breather is a glass tube, contains silica gel(foxed silica gel) that is impregnated by cobalt chloride as a moisture absorbent. filled the transformer oil into the cap as a debris filter.

2.2 When the swell-shrink for transformer oil volume caused by the transformer load or the environmental temperature changing, and forced the gas in conservator “breathing” through the dehydrating breather. By now, the moisture in the air is absorbed by silica gel, and a small amount of moisture and dust are absorbed by transformer oil in the cap, and thereby to ensure that the air enters into the conservator is dry and clean.

2.3 Foxed silica gel is blue color in dry state, and turns pink after absorbing the moisture. By now the silica gel is out of action and have to dry or replace.


3.Operation & Maintenance

3.1Checking the glass tube without broken and the silica gel does not turn to pink before operating. And then unscrewing the cap for filling with the transformer oil.

3.2 Remove the dehydrating breather from transformer when replace the silica gel, that can be poured out or putted into from the flange exit. It is better the silica gel is 2-7mm.

3.3 The silica gel after the damp can be turn to blue color completely when baked 8 hours under the 140 ℃ temperature (or baked 2 hours under 300℃temperature). Please note that the baking temperature shall not be too high, or silica gel will agglomerate.

3.4 During the operation, shall always keep watching if the silica gel color is changed, if the transformer oil is too dirty or if the oil level is reduced by evaporation.


4. Silica Gel with Cobalt Chloride Impregnation Method

You can use the original color silica gel when there is no foxed one for impregnating, and its steps are as follows:

4.1 Take the cobalt chloride that is 3% of the weight of silica gel dissolved in the water, and should ensure that the water is enough for absorption of the silica gel.

4.2 Immersed the 2-7mm silica gel in the cobalt chloride liquor, absorbed completely until it turns to pink color.

4.3 Dry the pink silica gel under 115℃ temperature, until it completely turns to blue color.


Draining Valve Installation and Operation Manual

1. Summary

This series of valve is a kind of shutter uses as a medium, that is installed at the bottom of oil tank only for oil draining. For the transformers that the capacity is 630KVA and below are equipped with a valve in diameterφ25, for the capacity is 800-6300KVA, the diameter of valve should be φ50. The structure is similar for both of them.


2. Structure & Operation

Draining Valve is connected with tank pipe by bolt, nut, etc. Please remove the cover plate and gasket in using, and unscrew the hand wheel for draining. But in usual, the cover plate and gasket should be well installed to keep the body cleaning.


Pocket for Mercury thermometer Operation Manual


Pocket for Mercury thermometer is placed on the transformer cover and closed to the LV bushing, that is for inserting a Mercury thermometer to measure the oil level temperature rising in operating, to guarantee the running safety and normally. Besides, the Pocket for Mercury thermometer is also for oiling using.


2. Structure

Pocket for Mercury thermometer will be inserted into the oil tank 130mm, only show the upper end and equipped with a cap and sealing washer. It should be filled with transformer oil for accurate measuring. The Mercury thermometer is prepared by user. The scale range can be 20-100℃(It is refer to the visible part after the Mercury thermometer is inserted ).


3. Operation & Maintenance

3.1 When measuring the oil level temperature rising, should unscrew the cap on the thermometer socket and then insert the thermometer. When used for oiling, should unscrew the thermometer pocket tube.

3.2 Please pay special attention to keep a safe distance from high voltage when observing the oil temperature.

3.3 The temperature shown on the thermometer is the top oil temperature, the top oil temperature minus the environment temperature is the oil temperature rising, In an ordinary way, the oil temperature rising should not exceed the maximum level which stipulated in the technical conditions. Otherwise, should immediately find out if there is any abnormal situation in operating.

3.4 If the mercury thermometer is fractured in the tube, then back-out the tube and poured out the

broken. Then put it back, and poured into the clean transformer oil

3.5 When remove or replace the thermometer pocket, the transformer internal oil level should be reduced to the tank cover.

3.6 If there is any oil leakage after the replacement of thermometer pocket, then it may be caused by gasket deflection slippage or aging damage, and shall be replaced and repaired.


Oil Sampling Valve、Plug and Earthing Bolt Operation Manual

1. Oil Sampling Valve

The Oil Sampling Valve is equipped at the tank bottom in LV side, only for oil sampling. When using, the cap should be removed and then rotated out the steel screw for 13mm.


2.  3/4 inch dual-use valve

The 3/4 inch dual-use valve is equipped at the tank bottom in LV side. It is used for oil draining and oil sampling for the transformer that the capacity is 160KVA and below. It is only need to unscrew the plug a bit when take oil sample, then the oil will flow out from the φ3 hole. But

when draining the oil, should unscrew the plug until to show the entire φ18 hole, then the oil will flow out quickly and smoothly.


3. Plug

A plug is composed of the plug, holder and seal wash. It is equipped respectively to tank bottom, tank cover, radiator and the bottom and top of the conservator, for the using of oiling, draining or air-bleeding.


4. Earthing Bolt

The Earthing bolt is welded in the LV side of tank bottom, for the earthing use of the transformer. Should connect the ground line between two washers and screw down the bolt for safety running. There is a nameplate marked besides the earthing bolt for easy identify.


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