Research Article Open Access

Impulse Volt-Time Characteristics of Oil and OIP Insulation

S. Venkatesan and S. Usa


Estimation of insulation strength of transformer oil and Oil Impregnated Paper (OIP) insulation, which constitutes major portion of insulation in power transformer, is an important task. Also, it is often necessary to evaluate the breakdown strength of oil and OIP under non-standard impulse voltages, since the oil and OIP insulation is subjected to non-standard waveshapes between inter-disc and inter-turn insulation. This necessitates for a generalized model to estimate the insulation strength of it. In this study impulse strength of transformer oil and OIP insulation have been extensively analysed for very small electrode gap distances ranging from 0.1 to 2.5 mm, which represents the inter-turn and inter-disc thickness of the insulation. The statistical mean volt-time characteristics for uniform and highly non-uniform electrode configurations are obtained experimentally for few gap distances. A Hyperbolic model is developed based on the Disruptive Effect (DE) model parameters, namely onset voltage (Uo) and Critical Disruptive Effect Area (DE * ) to predict the volt-time characteristics. The DE parameters are also utilised to predict the impulse breakdown characteristics of oil and OIP under non-standard impulse voltages of standard and unidirectional oscillatory impulse waveshapes for all the gap distances and the errors are found to be less than 10%.

American Journal of Applied Sciences
Volume 2 No. 2, 2005, 591-596


Submitted On: 3 January 2006 Published On: 28 February 2005

How to Cite: Venkatesan, S. & Usa, S. (2005). Impulse Volt-Time Characteristics of Oil and OIP Insulation. American Journal of Applied Sciences, 2(2), 591-596.

  • 7 Citations



  • Disruptive Effect
  • Volt-time Characteristics
  • Non-standard Impulse