Insulation plays a vital role in high voltage systems and a good understanding of the role of the different insulation materials used in high voltage systems is essential. The aim of this workshop is to discuss the basics of air, solid and liquid insulation in order to understand the need for testing and the limits of test voltages and currents applied to the different insulation materials. The advantages and disadvantages of testing with DC, Power Frequency and very Low Frequency AC voltages will also be discussed. A further need is to test the insulation with impulse voltages to determine its ability to withstand lightning induced surges. Evaluation of the condition of insulation is very important and diagnostic evaluation form a major part in testing of high voltage insulation. Two major components of high voltage systems are transformers and cables. Specific attention will be given during the workshop on the testing and evaluation of these two components.