A distribution transformer is one of the essential equipment in delivering power to the consumers. The main purpose of the distribution transformer is to step down the suitable voltage to the consumers. As an electrical engineer, it is important to know about the working principle and parts of the distribution transformer.
Distribution transformer parts
First I want to remember you about one famous sentence about a transformer. "A transformer is a static machine that transforms or converts one level of apparent power to another level".
In this blog, you can find the list of all parts of the transformer.
Distribution transformers are consist of the following essential parts
- Flange for mounting
- Tank and Tank cover
- Laminated Core & Winding
- Conservator
- Cooler (Radiator)
- LV bushing of transformer
- HV bushing of transformer
- Terminal connections
- Carriage
- Core-bolts
- Header
- Thermometer or sensing bulb
- Buchholz relay
- Breather
Flanges of transformer
Flanges of the transformer increase the strength of the transformer for mounting.
Tank and Tank cover
The tank is stored with transformer oil. The transformer oil reduces the heat of the transformer. Adequate cooling is required to decrease the rising heat of the transformer.
Oil spillage can be protected by tank cover.
Laminated transformer core and winding
The transformer core is wounded with winding, which effectively transfers magnetic flux from the primary winding to the secondary winding.
The transformer core is made up of highly permeable material in thick and thin slices.
Conservator tank of the transformer
The main purpose of a conservator in the distribution transformer is to store overflow oil due to the expansion of the oil. The air cushion or rubber bag is placed inside the conservator, which permits the expansion and contraction of transformer oil. The air cushion of the conservator avoids contact with the oil with the external atmosphere.
I recall one important thing to you "A conservator tank is only used with the oil-immersed type transformer." At the same time, many distribution transformers are coming as oil-immersed types.
The transformer oil level increases like milk when it is heated. This increment level can be detected by the oil level indicator for a purpose.
Whenever the transformer oil contract and expand due to temperature rise, then the conservator tank the transformer stores the overflow oil. Conservator tank of the transformer.
The conservator of the distribution transformer consists of an air balloon.
During overload conditions the temperature of the oil rises, this rising temperature causes the transformer oil or mineral oil to increase its volume. That increased oil gets stored in the conservatory.
Cooler of the transformer
From the above distribution transformer drawing, you can find the installation of a cooler on both sides of the transformer.
The coolers of the distribution transformer provide adequate cooling to the oil. If the temperature of the oil reduces, then the temperature of the windings and core is also gets reduced.
The cooler of the transformer is also called a radiator.
Transformer bushing
The input and output lines or cables are connected to the transformer bushes. The shape of the bushing is cylindrical. The bushing of the transformers is supported on the tank cover.
In the distribution transformer, the bushing is classified into
- HV bushing
- LV bushing
The bushes of the transformers are made up of porcelain material, which is insulated material. So, it is also called porcelain bushes. Other types of insulating materials are also suitable for making bushes of the transformer.
So, bushings of the transformer are used as the insulated device, which allows the conductor line or cable to the case of a transformer or circuit breaker safely.
Transformer LV bushing
The output cable or line is connected to the LV bushing. The size of the L.V bushing is small.
LV bushings are also called secondary bushings.
Transformer HV bushing
The Input line is connected with H.V bushing. The size of the HV bushing is big.
The H.V bushings are also called a primary bushing.
Terminal connection
The terminal connections of the transformer are located above the bushings of the transformer.
The terminals of the transformer are designed to connect cables or lines suitably to the bushing.
Carriage
The carriages of the transformer consist of wheels to move the transformers easily.
The below image did not cover the wheel.
Core-Bolts of distribution transformer
The core bolts of the transformer provide extra strength and reliability to the core. The core bolts are designed to absorb stresses on the core, and it also reduces the vibrations of the core when the transformer is in operation.
Headers
Headers of the distribution transformers are attached to the flanges of the transformer. The headers of the transformers are connected with the cooler or radiators as shown in the below diagram.
The headers of the transformer are strong enough to hold the radiators.
Thermometer or sensing bulb
Thermometers are fixed adjacent to the bushings for checking the temperature of the transformer oil. Sensing bulbs have come into transformer oil to detect the heat of the transformer oil accurately.
The thermometer is connected with an oil temperature indicator to alert the operator when the heat of the transformer exceeds the limit.
Buchholtz relay
Buchholtz relay is a protective device. In the distribution transformer, the Buchholtz relay is connected in the pipe between the tank and the conservator. Buchholtz relay operates and makes the sound when gases are generated in the oil.
If any electrical fault occurs in a transformer, it first reflects on the oil. Due to an electrical fault, the temperature of the oil increases abnormally and starts to evaporate. This evaporation creates gas and bubble. The gases of the transformer reach the Buchholtz relay.
Buchholtz relay begins to operate and alarm whenever it detects the gas.
Silica gel Breather
The breather acts as a nose for the transformer. The breather exerts the air in the rubber bag of the conservator and absorbs the fresh air from the atmosphere.
A silica gel breather is connected to the air cushion of the conservator tank. The fresh air makes the air cushion obsessed at the time of absorbing fresh air.
Quiz😀
Can you the missing part of the distribution transformer from the below image?
