Interest has risen among utilities in using natural ester (NE) insulating oils in transformers as a substitute for conventional mineral oil. However, present understanding on aging behaviour of NE-paper composite insulation system and knowledge on application of existing condition monitoring tools for NE-based insulation are inadequate. This limits the cost effective and reliable field applicat...

In order to analyze the cracking and aging reason of the silicone rubber current transformer (CT) insulation bushing used for 8 years from a 500 kV alternating current substation, characteristics including Fourier transform infrared (FTIR) spectroscopy, mechanical properties analysis, hardness, and thermo gravimetric analysis have been carried out. The FTIR results indicated that the external s...

Insulation used in transformer is mostly oil pressboard insulation. Insulation failure is one of the major causes of catastrophic failure of transformers. It is established that partial discharges (PD) cause insulation degradation and premature failure of insulation. Online monitoring of PDs can reduce the risk of catastrophic failure of transformers. There are different techniques of partial d...

Continuous monitoring of Power transformer is very much essential during its operation. Incipient faults inside the tank and winding insulation needs careful attention. Traditional ratio methods and Duval triangle can be employed to diagnose the incipient faults. Many times correct diagnosis due to the borderline problems and the existence of multiple faults may not be possible. Artificial inte...

Purpose – The power transformer is one of the most important pieces of equipment in a power system. The necessity for the optimum design of a power transformer arises because the design chosen should satisfy all the limitations and restrictions placed on it. This paper presents an improved fast evolutionary programming (IFEP) technique for the optimal design of a three-phase power transformer. ...

Most power transformers operating in a power system possess oil-paper insulation. A serious defect of this type of insulation, which is associated with long operation time, is an increase in the moisture content. Moisture introduces a number of threats to proper operation of the transformer, e.g., ignition of partial discharges (PDs). Due to the varying temperature of the insulation system duri...

T he size, performance and cost of a power electronic system are closely linked to the like parameters of the magnetic components. Since custom power transformers are widely used, transformer design is a frequent design process that has a signifi cant impact on system performance. Yet most high-frequency transformers use less than 25% of the available core window for effi cient current conducti...

The objective of this research is to compute the mechanical stresses in power transformer resulting from the currents more than rated value during its operation. Due to this high fault current, mechanical stresses are produced indifferent directions which may cause the damage of winding insulation. Various techniques have been adopted to analyze the stresses on transformer windings. For the acc...

Standard high voltage lightning and switching impulse tests are performed on Extra High Voltage (EHV) transformers during manufacture to ascertain the breakdown strength of insulation used. But during their service, transformers encounter numerous voltage transients of complex and varying wave shapes which do not necessarily resemble these standard surge type voltages. This paper reports the re...