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Transformer Maintenance Checklist 101

Transformer Maintenance Checklist 101

Transformer Maintenance Checklist

Transformers, like any other electrical equipment, require regular maintenance as well. With proper care, a transformer can function smoothly, increasing your productive workflow and ensuring a longer equipment life. We understand that putting a regular transformer check on your schedule might be hectic, with many different parts and components requiring individual care and attention almost daily, some even hourly. Hence, we have come up with the most comprehensive checklist for the maintenance of electrical transformers. Read on to learn more about the essentials to keep your transformer healthy in this article.

What Is The Importance Of Transformers In An Electrical Power System?

Transformers can be generally defined as voltage-controlling devices allowing the distribution and transmission of current. It is widely used in electrical industries to handle high voltage electric current and distribute it in low voltages for consumption. This is necessary as the high voltage current, when distributed directly to your homes, may lead to short circuits and destroy your electrical appliances.

Electrical transformers work on the principle of electromagnetic induction and work by increasing or decreasing the supply voltage. Thus it helps in the seamless movement of electricity from generating power plants to homes and offices. As such, the importance of transformers in an electrical power system would include:

  • Converts high voltage AC to low voltages so that it’s safer to distribute 
  • Safe medium to distribute electricity over long distances.
  • Helps prevent damage from High Voltage AC in a circuit
  • Controls the power of AC, which helps in lowering your electricity bill

How Does An Electrical Transformer Work?

As we know, a transformer works on the principle of electromagnetic induction and alternates current from higher to lower voltages. Hence, a transformer doesn’t itself create energy but is a mere distributor of energy by changing the voltages to suit the needs of different circuits.

The electricity enters the transformer through the primary coil. With this, there forms a moving magnetic field around the coil. The secondary coil from which the current is distributed at a lower voltage is placed near the primary coil. Thus, with the moving electric field, the current is either increased or decreased based on turns taken by the current. Wrapping the two coils together ( the primary and secondary coil) with the primary one with a few more loops than the other one generates a current at a lower voltage in the second coil than it is present in the primary coil.

Checklist For Daily Maintenance Of Transformers

There are a few components of transformers that are required for daily maintenance. This type of regular checking on your transformers is also known as conditional maintenance. As such, your daily checklist for electrical transformer maintenance must include the following:

  • Check the transformer yard to ensure no object may disrupt the transformer’s working.
  • Ensure that the re-extinguishers are free from dust so that they may quickly work in the face of an emergency.
  • Make sure the transformer is clean and placed in a proper space.
  • Keep track of any abnormal noises in the transformer to avoid costly breakdowns.
  • Look out for loose connections in your transformer, mostly around earthing and surge arrestors.
  • Keep a note of the reading on the winding temperature of your transformer.
  • Check the incoming supply of current. Keep it is in the ON position.
  • Also, look at the re-buckets occasionally to check for enough sand.
  • Ensure you check the oil temperature, hourly level, and voltage points.

Components That Require Annual Maintenance Of Transformers

You must get the transformer checked in detail, on a yearly basis. Some of the parts you need to check may include oil pumps, air fans, control circuits, and other components that work together for the function of the cooling system. With the cooling system checked, you can get an overview of the physical condition of your transformer. 

The bushing must be cleaned with soft cotton cloths and checked for cracks. Though it is recommended to have a half-yearly check for the oil condition of your transformer, a yearly oil test is mandatory for your transformer. You must also get a mechanical inspection done as a transformer works under heavy current pressures, which makes it prone to damaged parts.

Apart from this, you must get the marshalling boxes cleaned and checked along with other functions like illumination, space heaters, terminal connections, relays, alarms, control switches, etc. Other important aspects to check for may include insulation resistance, battery power, and DGA (Dissolve Gas Analysis).

The Ultimate Monthly Checklist For Your Electrical Transformer Maintenance

Transformer Maintenance Checklist

The ultimate checklist for your monthly electrical transformer maintenance would include the following:

  • Examine the transformer tank, bushings, cooling system, and accessories for any signs of damage, such as oil leaks, corrosion, rust, or physical damage.
  • Inspect the transformer for any debris, plants, or other objects that might interfere with its ventilation.
  • Utilize the gauge glass or level indicator to determine the oil level. Maintain the oil level within the prescribed range.
  • Check the oil for pollutants, color, clarity, and presence of contaminants. Take a sample of the oil for testing if it seems fuzzy or includes particles.
  • Utilize the sensors or gauges installed into the transformer to monitor the operating temperature. Keep a watch out for any abnormal increase in temperature.
  • Check the condition and functioning of the fans, radiators, and cooling fins.
  • Ensure sure that nothing that can restrict heat dissipation is in the way of cooling systems, such as dust, dirt, or obstructions.
  • Check for fractures and discoloration or symptoms of tracking in bushings and insulators.
  • Maintaining proper insulation may require cleaning insulators.
  • Check and tighten all electrical connections, including grounding connections and terminal nuts.
  • Keep an eye out for loose connections or overheating.
  • To ensure efficient moisture control, check the breather for the right color (typically blue to signify dryness), and replace or regenerate silica gel as necessary.
  • Check the functionality of any suitable pressure relief devices and reset them if necessary.
  • If the transformer has a gas monitoring system, examine gas levels for unusual activity or problems.
  • Keep thorough records of all maintenance tasks, including any anomalies noticed and the steps followed.
  • Ensure that all service staff receive regular training and remain acquainted with the most recent practices and safety regulations.
  • Consider setting a timetable or employing maintenance management software to track and organize normal repairs.
  • To reduce downtime, keep spare parts, oil, and necessary tools close at hand.
  • Consult a qualified transformer service provider for additional evaluation and repairs if serious problems or anomalies are found.


Given the importance of transformers in an electrical power system, a routine check of your transformers is worth it. In short, the key to better performance, higher reliability, longer durability and safe working of transformers is proper electrical transformer maintenance on a regular, daily basis. With so many intricate components and high pressure operations, scheduled maintenance of transformers can prevent your business from costly breakdowns or potential electrical hazards. 


1. What Are The Maintenance Requirements For A Distribution Transformer?

As with any other type of transformer, checking for oil level, voltage surges, connections, and regular visual and performance tests would be enough to manage a well-maintained distribution transformer.

2. Why Do Transformers Need Maintenance And Services?

Transformers work under high-pressure conditions converting high-voltage AC to lower voltages. Due to this, they may heat up faster, and they are open to the risks of electrical hazards. Hence, regular maintenance is necessary to ensure security and avoid the breakdown of a transformer.  

3. What Is Oil Needed In Maintenance Of A Transformer?

Oils inside the transformer can serve various purposes like lubrication, cooling, insulation, arc quenching, and damping.

Advantages And Disadvantages Of Electric Generator

Advantages And Disadvantages Of Electric Generator 

Advantages And Disadvantages Of Electric Generator

An electric generator, also known as a Dynamo or an Alternator, is a device that converts mechanical energy into electrical energy. It functions on the Principle of Electromagnetic Induction, discovered by Michael Faraday in the early 19th century.

The essential elements of an electric generator include a stationary part known as the Stator and a rotating part called the Rotor. The Stator consists of a series of wire coils arranged in a circular pattern, while the Rotor is a shaft with a set of electromagnets or permanent magnets attached to it. The Rotor is connected to a mechanical power source, such as a turbine or an engine, which provides the rotational energy.

When the Rotor spins, it induces a changing magnetic field in the stator coils. Faraday's law of Electromagnetic Induction states that this changing magnetic field generates an electric current to flow in the wire coils. The induced current can be harnessed and utilised as electrical power.

Electric Generators are commonly used in various applications where a portable or backup power source is needed. They can be found in power plants, where they are driven by steam turbines, gas turbines, or water turbines to generate electricity on a large scale. Portable generators are also available for smaller-scale applications, such as providing electricity during power outages or in remote areas.

Electric Generators Examples

There are various types of electric generators designed for different applications. Here are a few examples of electric generators:

  • Steam Turbine Generator: This type of generator is commonly used in power plants. A turbine is spun by the steam generated by burning fossil fuels or using nuclear energy connected to an electric generator to generate electricity.

  • Gas Turbine Generator: Gas turbine generators are used in power plants as well as for smaller-scale applications. They burn natural gas or liquid fuels to drive a turbine attached to an electric generator to generate electricity.

  • Hydroelectric Generator: Hydroelectric generators utilise the power of flowing or falling water to produce electricity. Water is utilised to spin a turbine, which drives the generator. Hydroelectric power plants often rely on dams or river systems for water supply.

  • Wind Turbine Generator: Wind turbine generators convert wind energy into electrical energy. Strong winds spin the turbine blades, which drive the generator to produce electricity. Wind farms consist of multiple wind turbines connected to a power grid.

  • Diesel Generator: Diesel generators are commonly used as backup power sources in various settings. They run on diesel fuel and consist of an internal combustion engine connected to a generator. Diesel generators are portable, efficient, and widely used for emergency power supply.

electric generator

Uses Of an Electric Generator

Electric generators have various uses and applications across various industries and settings. Here are some common uses of electric generators:

  • Power Generation: Electric generators are widely used in power plants to generate electricity on a large scale. They are driven by various energy sources such as steam turbines, gas turbines, or water turbines. Power plants provide electricity to residential, commercial, and industrial areas.

  • Backup Power: Generators are commonly used as backup power sources in case of power outages or areas with unreliable or limited access to the electrical grid. To ensure uninterrupted operations, they can provide temporary electricity to homes, buildings, hospitals, data centres, and critical infrastructure.

  • Remote Locations: Electric generators are essential in remote or off-grid areas without access to the primary power grid. They can provide electricity for remote communities, construction sites, campsites, outdoor events, and expeditions.

  • Construction and Industrial Sites: Generators are extensively used in construction sites and industrial facilities where a temporary or independent power supply is required. They can power construction tools, heavy machinery, lighting systems, and other equipment.

Advantages Of An Electric Generator

Electric generators offer several advantages in various applications. Here are some of the key advantages:

  • Power Generation Flexibility: Electric generators can generate electricity in diverse locations and situations. They can be used in remote areas, construction sites, emergencies, and any location without reliable access to the power grid. Generators allow for on-demand power generation where and when it is needed.

  • Backup Power Supply: Generators serve as reliable backup power sources during power outages or in areas with unreliable electricity supply. They can provide temporary electricity to homes, businesses, hospitals, and critical infrastructure, ensuring uninterrupted operations and essential services.

  • Quick Power Availability: Generators can provide electricity almost immediately after starting. This quick power availability is crucial in emergencies, construction projects, or when time-sensitive operations must continue without interruption.

  • Energy Source Flexibility: Generators can be designed to operate on various energy sources, such as diesel, natural gas, propane, gasoline, steam, or renewable sources like wind or solar. This versatility allows using different fuel types based on availability, cost, or environmental considerations.

  • Economic Benefits: Electric generators can lead to economic benefits in several ways. They can reduce downtime and productivity losses during power outages and provide power for remote operations. In regions with unreliable power grids, generators can help maintain operations, attract investments, and promote economic growth.

  • Emergency and Disaster Preparedness: Generators are essential components of emergency preparedness plans. They can provide power during natural disasters, emergencies, or situations where the main power grid is disrupted. This ensures that critical services, communication systems, and life-saving equipment remain operational.

  • Environmental Considerations: Some generators are designed to operate on renewable energy sources, such as wind or solar. This allows cleaner power generation reducing reliance on fossil fuels and minimising environmental impact.

Disadvantages Of An Electric Generator

While electric generators have many advantages, they also come with certain disadvantages. Here are some of the disadvantages associated with electric generators:

  • Fuel Dependency: Most generators require a fuel source such as diesel, gasoline, natural gas, or propane to operate. This dependency on fuel means ongoing fuel costs, fuel availability considerations, and the need for fuel storage. Additionally, fluctuations in fuel prices can impact the operational costs of running a generator.

  • Environmental Impact: Many generators, particularly those powered by fossil fuels, emit greenhouse gases, pollutants, and particulate matter during operation. These emissions contribute to air pollution and have environmental implications, including climate change and negative health effects. However, cleaner alternatives are available, such as generators powered by renewable energy sources like wind or solar.

  • Limited Lifespan: Generators have a finite lifespan and may require replacement or major repairs after a certain period. Factors such as usage intensity, maintenance practices, and operating conditions can impact the longevity of a generator. Planning for the eventual replacement of a generator is necessary to ensure continued power supply.

  • Safety Considerations: Generators pose certain safety risks if improperly operated or maintained. Risks include the potential for fuel leaks, electrical hazards, fire hazards, and carbon monoxide poisoning if generators are not installed or used correctly. Following proper safety protocols and guidelines is crucial to mitigate these risks.

  • Limited Efficiency: Generators have an efficiency rate determining how effectively they convert fuel or mechanical energy into electrical energy. Some energy is lost as waste heat during conversion, leading to lower overall efficiency than direct grid-supplied electricity. However, advancements in generator technology have improved efficiency levels in recent years.


Electric generators have numerous advantages, including flexibility, backup power supply, quick availability, and emergency preparedness.

However, electric generators have disadvantages: fuel dependency, environmental impact, noise and vibration, maintenance and operational costs, limited lifespan, size and space requirements, startup time, efficiency, exhaust and emission management, and safety considerations.

Overall, electric generators play a crucial role in various industries, providing reliable power in diverse settings and ensuring the availability of electricity for a wide range of applications.


1. What fuels can be used to power an electric generator?

Various fuels, including diesel, gasoline, natural gas, propane, and renewable energy sources like Wind or Solar energy, can power electric generators. The fuel choice depends on factors such as availability, cost, environmental impact, and the specific application.

2. Can electric generators be used as a primary power source?

Electric generators are typically used as backup power sources or when access to the primary power grid is limited or unreliable. While they can provide temporary or off-grid power, they are not typically used as the primary source of electricity in everyday situations due to factors such as fuel dependency, maintenance requirements, and operational costs.

3.Can electric generators produce clean or renewable energy?

Electric generators can produce clean or renewable energy depending on the type of generator and the fuel used. Generators powered by renewable sources like Wind or Solar energy produce clean electricity with minimal environmental impact. However, generators running on fossil fuels emit pollutants and contribute to carbon emissions.

Understanding the Breakdown Voltage of Transformer Oil: Importance and Benefits

Transformer Oil

Breakdown Voltage Of Transformer Oil

To understand the “Breakdown Voltage” (BDV) of transformer oil, we first need to get introduced to dielectric strength. Dielectric strength is defined as the ability of the oil to withstand electrical stress without breaking down. Here, breaking down refers to the failure of insulating properties.  

Now, let us move on to our main question and try to understand the BDV of transformer oil. 

What is BDV test of transformer oil

What is BDV test of transformer oil

Oil stored in drums loses its dielectric strength and must be tested and treated before use in electrical equipment. The breakdown voltage test of transformer oil is crucial for the smooth operation of the transformer. 

A periodical BDV testing of the transformer oil ensures the quality and healthiness of the transformer oil. Breakdown voltage is determined by observing the voltage at which a specific gap separates sparking strands between two electrodes immersed in oil. 

A low BDV value indicates that the oil contains moisture and conducting substances. As per the International Electrotechnical Commission (IEC), the minimum BDV value of transformer oil should be 30 kV.

Factors affecting the BDV value of transformer oil

Factors affecting the BDV value of transformer oil
  • Water is the most prevalent contaminant in transformer oil. Moisture transports charge carriers, reducing the dielectric strength of the oil. 
  • Acids, for example, are aging byproducts that deliver charge carriers via dissociation. They are also surface-active, which reduces surface tension. As a result, they promote bubble evolution as dielectric strength decreases.
  • Bubble evolution is also influenced by pressure. The breakdown voltage rises as the pressure rises. The breakdown voltage should decrease at pressures lower than atmospheric pressure.
  • Dry cellulose fibre particles lower the breakdown voltage by promoting bubble formation. 

Benefits of Regular BDV Testing of Transformer Oil

The Breakdown Voltage is the primary indicator of the health of the oil. It is a popular and important transformer oil test because it: 

  • helps determine the essential electrical properties of transformer oil
  • determines whether a specific oil is suitable for future use.
  • Informs whether filtration or regeneration is required.
  • help reduce oil costs and increase component life
  • prevent failures and maximize safety
  • Preventing equipment fires
  • Maintaining transformer reliability

Difference between breakdown voltage and rated voltage

The breakdown voltage refers to the limit voltage of the capacitor; above this voltage, the dielectric in the capacitor will fail. The rated voltage is the voltage that the capacitor can withstand over time and is less than the breakdown voltage.

Capacitors function properly at rated voltage and safely at voltages no higher than the breakdown voltage.


The breakdown voltage is the voltage at which the dielectric fails. It indicates the health of the transformer oil. Overall, the breakdown voltage of transformer oil is important because it allows the transformer to operate smoothly and prevent failures. 

BDV results are better in dry and clean oil than with moisture and other conducting impurities.

Air-insulated switchgear vs gas-insulated switchgear

Air insulated switchgear vs Gas insulated switchgear

Air insulated switchgear vs Gas insulated switchgear

Air-insulated switchgear (AIS) and gas-insulated switchgear (GIS) are two types of equipment employed in the electrical power distribution and transmission industry. While AIS is commonly used in low and medium-voltage systems, GIS is used in high-voltage systems. 

In this article, we discuss their benefits, applications and differences to provide a thorough understanding of AIS and GIS. 

What is air-insulated switchgear?

Air-insulated switchgear is a secondary power distribution device and medium voltage switchgear that helps redistribute the power of a primary power distributor powered by a high voltage distribution transformer. 

AIS controls, protects and isolates electrical equipment in power transmission and distribution systems. The equipment is designed to be operated in the air at atmospheric pressure, which is why the name “air-insulated.”

What is air-insulated switchgear

Advantages of AIS

  • It is a primary choice for areas with extensive space.
  • Due to low construction and switchgear costs and good design, the system is financially viable.
  • Less time spent on construction makes it suitable for immediate installs.
  • All the equipment is visible, making maintenance simple. Faults are simple to identify and fix

Applications of AIS

  • Power generation stations 
  • Airports 
  • Railway stations 
  • Shopping malls 
  • Oil and gas 
  • Mining 
  • Marine
What is gas-insulated switchgear

A gas-insulated switchgear is a composite device enclosed in a solid metal frame comprising electrical devices like transformers, circuit breakers, bus cars, surge arrestors, etc. These components are housed in shielded chambers with barrier devices and submerged in sulfur hexafluoride gas (SF6).

The main uses of a GIS substation are switching, separating, converting, monitoring, and distributing electrical energy in power systems. SF6, an inert gas with high insulating qualities, chemical stability, and thermal stability, is used as the primary component of a GIS device.

Advantages of GIS

  • The earthed metal enclosure provides the attending staff with a secure working space. 
  • Because the insulation system is less disrupted by compartmentalized containment of the live sections, the system is very dependable.
  • Minimal maintenance due to efficient design and protection from the weather.
  • Rapid assembly as a result of thorough pre-assembly

Applications of GIS

  • Power transmission
  • Railways
  • Grid integration of renewable energy production facilities
  • They are favored in big cities because there is limited room available in cities.
  • Valleys, as well as mountain regions
  • Underground substations
  • Substations on sea or lake
  • HVDC-based terminal substations for transmission
  • Industrial complexes

Differences between air-insulated switchgear and gas-insulated switchgear


AIS (air-insulated switchgear) 

GIS (gas-insulated switchgear) 

It has a metal-clad system that employs air insulation.

It uses the gas sulfur hexafluoride for insulation. Sulfur hexafluoride is much heavier than air and offers great extinction behavior.

Three-position draw-out circuit breakers are used in the metal-clad AIS.

GIS systems use fixed-mounted circuit breakers. 

More economical for low/medium voltage systems.

It is expensive as compared to AIS.

More maintenance cost over a lifetime 

Less maintenance cost 

The AIS breaker is removable for maintenance & troubleshoot 

The breakers here are ‘sealed-for-life.’ 

AIS systems cover more space 

GIS systems cover less space 

More installation time 

Less installation time 

Visual inspections of AIS systems should be done every year to every two years.

GIS switchyards require significantly less maintenance


Gas-insulated switchgear is mainly used in industries with high power demand and limited space to install equipment. However, it can be more expensive in the long term, requiring more specialized tools and skilled professionals to install and maintain. 

On the other hand, air-insulated switchgear is a more common and economical alternative for low and medium-voltage systems.