This presentation provides an overview of power transformers. It discusses that power transformers are static machines that transform power from one circuit to another without changing frequency, and are used between generators and distribution circuits. It then describes the typical power ratings of small, medium, and large power transformers. The main components of power transformers are then outlined, including bushings, the core and winding, conservator tank, breather and silica gel, cooling tubes, tap changer, transformer oil, and Buchholz relay. The functions of these key components are explained at a high level.

1. Presentation
on
POWER TRANSFORMER
Presented by:
Sudarshan Pandey
Department of Electrical Engineering
IOE,ERC,Dharan

2. Introduction
 Power transformer is static machine used for transforming power from one circuit to
another without changing frequency.
 Used between generator and distribution circuit.
 Usually rated at 500Kva and above.
 Types:
1. Small power transformers(500-7500KVA)
2. Medium power transformer(7500KVA- 100MVA)
3. Large power transformer(100MVA and above)

3. Components of power transformer
HT/LT bushing
Core and winding
Conservator
Breather and silica gel
Cooling tubes
Tap changer
Transformer oil
Buchholz relay

4. HT/LT Bushing
 An insulated device made of porcelain.
 Terminal that Allows electrical conductor to pass through.
Core
 Support HV/LV winding
 Provide magnetic path of low reluctance
 Made of silicon-steel laminated to reduce the eddy current loss
Winding
 Two types of winding : LV and HV winding
 Made of copper conductor

5. Conservator tank
 Fitted between breather and tank
 Simply metal constructed tank
 Act as a oil reservoir
 Protect transformer from bursting
Breather and silica gel
 Fitted on top of conservator tank
 Associated with silica gel bowl
 It limits the gases from the tank and absorb the air from the
environment .
 Silica gel absorb the moisture content in air

6. Cooling tubes
 Improves the cooling performance in transformer
 Heated oil passes through tubes get cooled via tubes
Tap changer
 Maintain the voltage
 Always provided in HV side
 Can be done on OFF load and ON load

7. Transformer oil
 Serves the double purpose of cooling and insulating
 Bad conductor of electricity but good conductor of heat
 Hydrocarbon mineral oil is used
 No impurities like Sulphur and its compound
 Flash point :160 degree Celsius
 Dielectric strength 30KV/mm

8. Buchholz relay
 Install between transformer tank and conservator tank
 Gas actuated relay
 Used for internal fault detection and protection
 Minor fault actuates alarm circuit
 Severe fault actuates both alarm and trip circuit

9. Thank you!