1. Introduction

High direct, alternating and impulse voltages as well as the corresponding currents play an important role in the electrical energy supply, but also in many other areas of physics and technology. The high-voltage apparatus and other equipment used for this purpose are subjected to a series of tests prior to commissioning, which allow limited information on their reliability and expected lifetime. The decisive factor is the proper execution of high-voltage insulation, which is based inter alia on the specific knowledge of the solid, liquid and gaseous insulating materials used. All tests require accurate measurement techniques and the use of calibrated measuring systems. In this context are terms and content such as quality assurance, calibration, traceability of the measurements to the SI units, measurement uncertainty, internationally agreed test specifications, accredited testing and calibration laboratories. In the following chapters, the old but still valid fundamental basics and principles of high-voltage measurement techniques are combined with the more recent developments in all the above-mentioned fields under particular consideration of digital measurement technology and data transmission.