ABSTRACT
This chapter describes various methods for measuring high voltages and high transient currents. When sphere gaps are used in high-voltage measurement, one of the spheres is earthed and the other is connected to high voltage. A horizontal sphere gap arrangement is sometimes preferred at lower measured voltages. Under impulse voltages, the voltage at which there is a 50% breakdown probability is recognized as the breakdown level. Voltage transformers are used to measure high AC voltage accurately. The voltage on the secondary side is closely proportional in amplitude to and almost in phase with the voltage on the primary side. In cascaded voltage transformers the primary winding is distributed over a series of coils wound on separate cores which are mounted in oil-filled porcelain containers, stacked in series. Impedance can be used in series with a microammeter or a milliammeter for the measurement of high voltages.
