What is an Electrical Transformer?

15 Main Parts of Electrical Power Transformer

A transformer is a device that transfers electrical energy from one primary circuit to another Secondary circuit, using the principle of electromagnetic induction. during the transformation of electrical energy from one circuit to another, the frequency remains constant.

Parts of the Electrical Transformer

A transformer consists of different parts that play an important role in working. The different parts are

core
Steel tank
Windings
Conservator
Breather
Thermometer
pressure relief pipes
Valves
Buchholz Relay
Bushings
Tap changing switch
Oil gauge
Radiator
Cooling fans
Oil pumps

core of transformer

The core plays an important role in transformers due to its ability to transfer energy between the primary and secondary windings. The core provides a closed magnetic path in the circuit. The core's main purposes are reducing eddy current losses and providing a consistent magnetic path. Each core sheet is insulated with a laminating medium with a thickness of 0.35mm at 50 Hz and 0.5mm at 25 Hz frequencies. The core is constructed with laminated Silicon steel whose purpose is to reduce eddy current and magnetizing current. There are different types of cores are constructed as per transformer requirements.

15 Main Parts of Electrical Power Transformer

In standard practice, a single-phase transformer core consists of 2 legs and a three-phase transformer core consists of 3 legs. The core is constructed circular and rectangular depending on the capacity of the transformer. This laminated core is also tight with the help of bolts.

Steel tank of Transformer

The steel tank of a transformer is used to protect the transformer's core and windings. It is made of high-quality steel to withstand mechanical stress, corrosion, and environmental factors. This tank is filled with insulating or mineral oil that provides insulation and cooling. There are different types of steel tanks including

15 Main Parts of Electrical Power Transformer

Types of Steel Tank

Plain Steel Sheet Tank
Tube Tank
Tank with separate coolers
Transformer Oil Tanks without a cooler
Radiatorpanel type tanks
Tubular cooling-type tanks
Corrugated wall-type transformer tanks
Pressed steel tank
Welded steel tank

Windings of the Transformer

A single-phase transformer consists of one primary and secondary winding and a three-phase transformer consists of three primary and three secondary windings. These winding are connected in proper sequence. The windings are constructed in discs, helical coils, springs, Cylindrical and foil type. we use copper and aluminium material in the winding.
15 Main Parts of Electrical Power Transformer

Windings Types of Transformer

Disc Type Winding
Helical Type winding
Springs Type winding
Cylindrical Type winding
Foil Type winding
Cross over Type winding
Aluminium Type winding

15 Main Parts of Electrical Power Transformer

Conservator of transformer

A conservator is a small cylindrical tank on top of the main tank in a transformer. It is connected to the main tank via a pipe. In transformers with a rating above 1MVA, a Buchholz relay is typically installed between the conservator tank and the main tank.
15 Main Parts of Electrical Power Transformer
The conservator helps to maintain a constant oil level within the transformer and prevents the entry of moisture and air into the main tank.
The main function of a conservator is
When oil is heated and expended it provides a space.
It reduced the oxidation to reduce the oil surface area.

Advantages of Conservator

The conservator provides extra space for the expansion and contraction of transformer oil as it heats up or cools down during operation.
The conservator helps regulate the temperature of the transformer oil.
Many conservators are equipped with oil level indicators and alarms, allowing for continuous monitoring of oil levels.
The use of a conservator improves the overall safety of the transformer.

Breather of Transformer

A breather is a device used in transformers to control the moisture content of the air in the oil. It consists of a container filled with desiccant material, such as silica gel, that absorbs moisture from the air. The breather is typically installed on the vent or opening of the transformer tank.
15 Main Parts of Electrical Power Transformer
Mutual Flux

Working of Breather

When oil expands due to heat, the air is expelled from the tank, and when oil contracts, the air is drawn in from the environment. One end of the breather is connected to the conservator tank. Inside the breather, there is a box filled with silica gel. When air enters the tank, it may contain moisture, which can adversely affect the insulation of the winding. To prevent this, silica gel absorbs moisture from the incoming air, ensuring that only dry air enters the transformer. As the silica gel absorbs moisture, its colour changes from blue to pink, indicating that it needs to be replaced.

Advantages of Breather

Breathers control the moisture content of the air.
Breathers help prevent insulation deterioration.
Breathers also help filter out other airborne contaminants, such as dust, dirt, and debris.
Many modern breathers use eco-friendly desiccant materials, making them environmentally friendly solutions for moisture control in electrical equipment.

Thermometer

A thermometer is a device used to measure the temperature of the transformer's components, particularly the transformer oil and winding temperatures.

Types Of Thermometer

Dial Thermometer
Digital Thermometer
Winding Temperature Indicator (WTI)
Oil Temperature Indicator (OTI)

15 Main Parts of Electrical Power Transformer

When the temperature surpasses the threshold value, a signal is triggered, leading to the tripping of the transformer. A dial-type thermometer is employed within the transformer for temperature monitoring. This thermometer is linked to a sensor responsible for detecting the temperature of the transformer oil. The designated threshold temperature for the oil is set at 105 degrees Fahrenheit.

pressure relief pipes

pressure relief pipe is mounted on the main tank of the transformed. it is a curved pipe that protects from excessive pressure. When Decomposition is started in the transformer high pressure is generated and pressure relief pipes are used to withdraw this high pressure and protect the transformer from bursting. The structure of the pressure relief vent consists of adjusting the spring and bellows that sense the high pressure and operate mechanically shaft.

15 Main Parts of Electrical Power Transformer

Valves of Transformer

Different valves are used in the transformer to fill the oil, Drain the oil, Filter the oil and sample the oil. Valves in transformers are mechanical devices used to control the flow of oil and gas.
15 Main Parts of Electrical Power Transformer
Types of Valves
Pressure Relief Valves
Gas Release Valves
Drain Valves
Check Valves
Isolation Valves

Buchholz Relay

Buchholz is a gas-operating relay that protects the transformer from bursting. It's connected between the main tank and the conservator. It consists of two floats. one float is operated in an emergency condition and connected to the trip circuit. The other float generates an alarm signal. when the oil level is low or another internal fault appears in the transformer the gases are produced due to the decomposition of insulating material. Due to the lightweight of the gas, it moved to the upper side and operated the Buchholz relay float. This float is connected to the alarm circuit and trips the circuit.

15 Main Parts of Electrical Power Transformer

Advantages of Buchholz Relay

Early Fault Detection
Protection Against Major Faults
Reduced Downtime
Improved Safety
Enhanced Transformer Lifespan
Monitoring Oil and Gas Conditions

Bushings of Transformer

The bushing is an insulating Component that connects the transformer windings to external conductors. bushings are made from porcelain and oil-filled capacitors. There are two types of busing one for L.T and another for H.T side. To protect from lightning arching horns are used on the upper and lower sides of bushings. There are two types of bushings w.r.t construction, Sealed condenser type oil-filled bushing with voltage ratings of 34.5 kV and plain bushings with voltage ratings of 25.

15 Main Parts of Electrical Power Transformer

Tap changing switch

A tap-changing switch is used in transformers to regulate the turn ratio of the transformer windings.

There are two types of Tap changing Switch
Offload Switch
On load Switch
Offload Switch

The Offload tap changer adjusts the voltage ratio of the transformer winding. This adjustment is when the transformer is offline because altering the turn ratio can generate arcs within the windings. In a small transformer, the internally operated switch is used and for a large transformer, the external switch is used the transformer.