How Indian Manufacturers are Testing Transformers?


Transformer is an electromechanical component operated by professionals on the principle that every electrical field generates a magnetic field and each magnetic field creates an electrical field. Transformers manufacturers India are sharing this post to make you learn about the steps that help in testing the transformer. 

  • Perform a visual inspection 

Overheating causes the internal wiring of transformer to run at higher temperatures. This is a common reason behind the failure of transformer. If the exterior of transformer is bulged or showing burn marks, do not perform testing. 

  • Determine the transformer wiring 

The labeling should be clearly available on the transformer. However, it is always a great idea to get a schematic of the circuit having the transformer to find how it is connected. This schematic can be found in the product documentation or on the manufacturer’s website. 

  • Determine the inputs and outputs of transformer 

The initial electrical circuit generating the magnetic field should be connected to the primary winding of the transformer. The voltage being shared to the winding should be on both the transformer schematic and label. The other circuit retrieving power from the magnetic field should be connected to the secondary winding of the transformer. 

  • Determine the output filtering 

It is common to connect diodes and capacitors to the transformer secondary to shape the alternate current power from the output into direct current power. This shaping and filtering will be unavailable from the label of the transformer. It will be shown on the schematic. 

  • Make preparations for measuring circuit voltages 

You must remove panels and covers as per the need to access the circuits that contain the transformer. For voltage reading, use a digital multimeter, which is usually available at electrical supply stores and hobby shops. 

  • Confirm proper input to the transformer 

Switch on the power. Use the digital multimeter in AC mode to measure the transformer primary. If the voltage is less than the 80% of the expected result, the fault may be existed in either the transformer or the circuitry offering the primary with power. If it is the case, you need to separate the primary from the input circuit. 

  • Measure the secondary output of the transformer. 

You must call professionals to perform this testing. There are transformers manufacturers India that provide expert assistance on request. You can contact them and book a testing service for your transformer.

Do You Know Which Option Works For Your Transformer Oil Purification System?


Insulating oil used in the transformer should be purified using oil filtering system/ purifier/ or transformer oil purification plant. To enhance the transformer oil, you need to eliminate moisture, gas, and solid content from it. Manufacturers are practicing oil purification with several types of oil treatment equipments or oil filter machines to complete the treatment of transformer oil, insulating oil for better results.

For general impurities treatment, i.e. removal of dust and water from the transformer oil, manufacturers are using vacuum oil purifiers. They found vacuum oil purifiers best solutions as these equipments not only remove the water, gas, and big size particles from the insulating oil, but can effectively remove minor impurities as well.

Next best option is oil heating degassing vacuum dehydration. This method works on the principle in which there is a vacuum installed within the chamber. It uses oil mist spray approach for heating of transformer oil. This lets the gas and water content vaporized. Meanwhile, most of the water content gets cooled down by condenser and is expelled through water container. The temperature of oil is generally 60 degree and it remains low to prevent ageing of the transformer oil.

This dehydration and degasification approach works better than other traditionally used methods.

Dirty oil or highly contaminated transformer oil is mixed with smaller impurities and the molecules of oil combine with these impurities to form colloidal contaminated transformer oil. Manufacturers use specialized waste oil processing system to treat dirty oil. These systems use silica or activated alumina as adsorbent.

In order to ensure complete access to silicone and transformer oil, and to facilitate silica gel removal in the waste oil processing system, silica gel tank set up into numerous partitions. Once the transformer oil is heated into the gel tank, the process is repeated to achieve full absorption effect. When the contaminants are absorbed, the oil is injected into the oil filtration tank.

During the regeneration of oil, it is important to check and monitor the absorption effect. Loading used waste oil cans or containers should be cleaned and dried thoroughly prior usage for the normal production of the oil system.

If you want to go in detail, you may contact transformer oil purification services provider in your town. There are service providers that offer live demo of transformer oil or insulating oil purification. Visit such store in your local and gather more information.

High Vacuum Transformer Oil Filtration Machine Performance


Your transformer life can be extended if you regularly perform transformers oil filtration to expel the moisture, solids, and gaseous contaminants from the oil. Oil filtering machines help you achieve your goals and extend the life of the transformer. Equipments supplied by the manufacturers are used for processing of transformer insulating oil. The process includes degasification, dehydration, filtration, and de-acidification (optional).

Transformer oil purifier is designed for processing transformer oil in the field, workshops, in drums, storage tanks, directly in transformers, or inside circuit breakers or tap changers.

Manufacturers that are supplying these equipments to their clients are also providing training to their representatives and staff employees.

Operating characteristics

Suppliers are providing stationary, portable vacuum oil purification devices as per the customer’s application. The equipment is installed on a common base or within a trailer and provided in the form of pre-piped and pre-wired packing.

Conditions for installing the equipment should be considered on a serious note. The installation has to be designed to operate satisfactory at regular temperatures ranging from 0 degree Celsius to 55 degree Celsius.

The installation is designed and created to allow certain operations during combined operations of oil heating:

  • Degasifying, dehydration of oil under high vacuum
  • Removal of carbon/solid contaminants from transformer oil

The process of purification includes:

  • Water removal – equipment removes the moisture from the oil.
  • Gas removal
  • Solid removal
  • Dielectric breakdown
  • Acidity correction

Process description

Transformer insulating oil is drawn into the vacuum system through a positive displacement pump. The oil is passed through an inlet strainer. Prior entering into the vacuum chamber, where gases and water inside the oil are exposed to vacuum through efficient dispersion and expelled via vacuum pump, transformer oil is heated using electrical heater.

Oil purification equipment uses porous cartridges within the vacuum chamber for the maximum exposure of oil to the vacuum effect. Purified oil is passed by the pump with efficient filter element where oil polishing occurs.

Once the oil is passed through the fine filter, it flows through a flow meter before entering the outlet or re-circulation valve. This step is completely optional.

If you want more details about transformers oil filtration machine, contact manufacturers in your town today. You can search them online or look up for them in directories. You can share your experience with other readers in comments.

How About Using Refurbished Indian Power Transformers?


Power transformer is stationary equipment that doesn’t have components that require special engineering. Manufacturers of power transformers India are always in favor of encouraging people who cannot afford brand new transformer to use refurbished model. Dismantling of a transformer and replacement of the components is an easier task to do for experts. Major components that remain intact over the years are:

  • The main tank
  • The external metallic fittings- radiator, conservator, and piping
  • The core and frame
  • The mechanical protection devices and control cubicles

Manufacturers inspect some components prior performing the replacement procedure. They check the tap changer or diverter switch, cooling fans, protection devices, bushings, and current transformers. There are certain components that need to be replaced-

  • The coils forming the HV / LV windings
  • New gaskets for consumables and sealing
  • Press board material used and applied for insulation and spacing

There are many reasons to consider refurbishment methods. Manufacturers will brief them all-

  • Cost saving – At times, people sell their transformers too early due to failure of some components. They never think about repairing or refurbished transformer. But if you have limited cash, you can have a refurbished transformer for your site. It will save your cost a lot.
  • No design cost- since in refurbished transformer, only a component or components are replaced and repaired by the engineers, they don’t need to work on the design of the model. You will get a readymade transformer which is refurbished by experts. So, no designing cost is involved in the deal.
  • Environmental friendly- Recycling is always good for environment. It is always good to do something that keeps your environment great. Refurbished transformers are the environmental friendly products.
  • No civil work is needed
  • Control and indications remain same – There is no change made to the controls and indication system by the engineers. So, you can freely opt for refurbished transformer.
  • Short cycle operation – You can aim your transformer for 16 weeks operation.

The only disadvantage of a refurbished transformer is the rating of the transformer that has to be retained. You cannot increase the rating anyway.

What facilities are required for refurbished power transformer?

You will need a workshop with suitable un-tanking facilities of the Live part and coil replacements with new ones. You will need arrangement of cleaning and washing of main tank and core and retightening of core. You will also require testing facilities for the device and its components. Oil regeneration unit with oil tanks on site will also needed for treatment and storage. Oven should be available for drying the assembly prior sealing for transportation.


Can you tell distinct types of transformer oil used in systems for purification?

You will find two types of transformer oils in the market, i.e. paraffin based transformer oil and naphtha based transformer oil. There are plants intended by engineers that perform transformer oil purification in efficient way. When we compare both the transformer oils, we discover that paraffin oil is less oxidized. However, oxidation product like sludge in naphtha oil is highly soluble than paraffin oil.

This is why sludge present in naphtha oil is never precipitated at the bottom of the transformer. So, it enables oil circulation, and also let transformer to perform normally. Paraffin oil has lower oxidation rate as compared to Naphtha oil.

Quality transformer oil offers ideal insulation in an electrical power transformer and absorbs heat (works like coolant). Moreover, it helps preserve the core and windings of the system.

Other than these oils, mineral oil is also used for transformer since 18th century. Let’s overview the purification process of petroleum-

  • Crude petroleum

Crude oil is being extracted from crude petroleum. It has long chains of carbon compounds and smaller content of nitrogen and sulphur, accumulated over millions of years under high pressure inside earth’s crust. Hydrocarbon molecules classification is-

  • Paraffin
  • Cycloalkanes
  • Aromatics


Refining petroleum – This crude petroleum needs to be refined to classify petroleum products like gasoline, LPG, lubricating oils, kerosene oil, etc. Refining is done inside the vacuum distillation tower known as fractionating tower where multiple catalysts and distinct temperatures are used to classify the range of products.

Transformer oil or insulating oil is extremely refined mineral oil that is obtained from fractional distillation process with crude petroleum processing. You can classify transformer oil parameters in following categories-

  • Electrical parameters - dielectric strength, specific resistance, acidity, water content.
  • Physical parameters - Viscosity, flash point, inter facial tension, etc.

Moisture and dissolved gases- enemies of transformer oil : 

Moisture or water content is a serious contaminant that put adverse effect on insulation of the transformer and may be you have to call engineerings for repairing the transformers. Moisture makes the transformer oil less thick and the content is directly proportional to transformer oil aging.

Dissolved gases are other contaminants that degrade transformer oil quality.

This story is shared by experts performing transformer oil purification everyday inside their service center using latest tools and technologies. The purpose of this post is to let the readers know about transformer oil filtration range used by industries for their installed transformers.

You can share your reviews for this post with us.

Things To Be Consider Before Transformer Oil Filtration

There are things to be consider before begin any oil filtration process for the transformer. You can conduct transformer oil filtration once you complete the process and perform all the tests to ensure the right time for energizing the transformer device. You should never energize the transformer without performing these tests and checks.


Just in case any of the tests mention below fail and transformer is energized, you may end up with serious issue that will not be good for your transformer health. So, read these tests and ensure proper checks before starting energizing of the transformer.

  • Insulating fluid test

Take a sample fluid and test its dielectric strength, which should be minimum 26 kv or more.

  • Pressure test

Look for leakage in transformer tank using pressurizing method. Pressurize the tank with dry air or dry nitrogen using pressure test fitting at 3-4 PSIG pressure. Let it stand under pressure for minimum one hour to two hours and then check the tank and its fittings and look for leakage points. You can easily detect the leaks by applying soap solution to all joints, welds, cable connections, and pipe fittings.

You can later reduce the pressure to 1-2 PSIG once you are done with this test.

  • Ratio test

You need to do ratio test to ensure that the coil ratios and tap changer connections in transformer are correct. For this test, you must call experts who will use specialized tools and technology to perform ratio test of transformer.

  • Test continuity and resistance

Perform a continuity and resistance test on every winding of the transformer. Once you measure the winding resistance, compare the results with factory test values. 

  • Ensure tap changer setting

Check the tap changer setting in order to make sure that it is set to the proper position as per the required voltage.

  • Grounding 

You must check and ensure about the grounding of the transformer tank. It should be permanently and successfully grounded.

  • Fasten the loose connections 

Look for loose connections and fasten them if you don’t want to make damage to insulation.

  • Check finish 

Make sure the surfaces of the tank are painted well so that transformer will remain untouched by rust or corrosion.

  • Bolted connections

Make sure all the bolted connections are tightened.

  • Tools

Check and ensure all the tools and equipments are accounted for and have been ejected from the system.

These are the obligatory tests and checks that one should perform prior starting transformer oil filtration process. A lot more tests are there to perform; you can find them in the manual shared by your manufacturing unit.

You Can't Really Afford Neglecting Transformer Oil Filtration Process

Transformer oil has ability to maintain its stability at high temperature and also has significant electrical insulating characteristics. Due to extreme high temperature stability and super insulating property, transformer oil is been used over the years. Apart from transformers, insulating oils are also used for high voltage capacitors, few kinds of high voltage switches, circuit breakers, and fluorescent lamp ballasts in large quantity.

Transformer oil is primarily used for insulating purposes and at times it also works as a coolant inside the machine. You should maintain the oil clean and dry in order to achieve and sustain dielectric strength and insulating performance. And thus, need for Transformer oil filtration process can be never fade.


What Do You Understand About Oil Filtration?

Oil filtration is the process which reduces or eliminates all the visible contaminants from the oil and makes it pure for use. Transformer oil filtration and purification process is effective and efficient for removing dissolved gases and water from transformer oil along with dust particles.

Do you know? Even packed unused oil is impure as it may have absorbed moisture from the air or may have contaminated in the barrel it was stored in. Transformer oil filtering is a critical process to eliminate solid particles and moisture content from the oil. You can enhance its electrical properties by filtering, degassing, and dehydration process. Oil filtration machine keeps the transformer oil well-maintained and enhances its life.

Why You Need Such Processes?

Almost 75% of transformer failures happen due to deteriorated transformer oil. To sustain long life and high performance of the transformer, you always need to filter and purify oil before introducing it to the transformer. Regular maintenance will lead to utmost results and save you from paying heavy Transformers repairing. Ignoring Transformer oil filtration can result in-
  • Arcing
  • Corona discharges
  • Overheating
  • Lower insulating strength
How to Find the Right Filter For Your Transformer Type?

Most people are using mechanical filters, which have tendency to eliminate dirt, debris, and large contaminants. Yet manufacturers don't recommend these filters because these are unable to filter microscopic oil byproducts. You can find the suitable, economical, and effective filtration device for your transformer by sharing transformer details with the vendor. If you can't tell the type of transformer you are using, you can't get the right filtration model and will require professional assistance to sort the issue.
Get More Info:- Transformer Oil Purification Processes And Methods