AS IEC 60060.1:2018 pdf download – High-voltage test techniques Part 1: General defnitions and test requirements.
5.1.3 ripple amplitude half the difference between the maximum and minimum values NOTE In cases where the ripple shape is nearly sinusoidal, true r.m.s. values multiplied by √2 are acceptable for determination of the ripple amplitude. 5.1.4 ripple factor ratio of the ripple amplitude to the value of test voltage 5.1.5 voltage drop instantaneous reduction of the test voltage for a short duration of up to a few seconds NOTE Voltage drop may be caused by non-disruptive discharges. 5.2 Test voltage 5.2.1 Requirements for the test voltage 5.2.1 .1 Voltage shape The test voltage, as applied to the test object, should be a direct voltage with not more than 3 % ripple factor, unless otherwise specified by the relevant Technical Committee. NOTE Increasing ripple amplitude is directly related to increasing resistive load currents. Dielectric testing where heavy streamers are present may cause excessive ripple and/or voltage drop. Wet testing and pollution testing by their very nature require sources suitable for high resistive currents, see IEC 60507. 5.2.1 .2 Tolerances For test durations not exceeding 60 s, the measured values of the test voltage shall be maintained within ±1 % of the specified level throughout the test. For test durations exceeding 60 s, the measured value of the test voltage shall be maintained within ±3 % of the specified level throughout the test. NOTE It is emphasized that the tolerance constitutes the permitted difference between the specified value and that actually measured. This difference should be distinguished from the uncertainty of a measurement (see 3.3.1 ). The source characteristics should be sufficient to allow charging of the capacitance of the test object in a reasonably short time. In the case of wet or pollution tests, the source, including its storage capacitance, should also be adequate to supply the transient discharge currents of the test object with a voltage drop of < 1 0 %.
5.2.4 Measurement of the test current When measurements of current are made through the test object, a number of separate components may be recognized. These differ from each other by several orders of magnitude for the same test object and test voltage. They consist of: – the capacitive current, due to the initial application of the test voltage and to any ripple or other fluctuations imposed on it; – the dielectric absorption current, due to slow charge displacements within the insulation and persisting for periods of a few seconds up to several hours. This process is partially reversible, currents of the opposite polarity being observed when the test object is discharged and short-circuited; – the continuous leakage current, which is the final steady direct current attained at constant applied voltage after the above components have decayed to zero; – partial discharge currents. Measurement of the first three components necessitates the use of instruments covering a wide range of current magnitudes. It is important to ensure that the instrument, or the measurement of any one component of the current, is not adversely affected by the other components. Information concerning the condition of the insulation may sometimes be obtained by observing current variations with respect to time, during non-destructive tests. The relative magnitude and the importance of each component of current depend on the type and the condition of the test object, the purpose for which the test is being made and the duration of the test. Accordingly, the measurement procedures should be specified by the relevant Technical Committee, especially when it is required to distinguish a particular component. Current measurements shall be made with a calibrated measuring system.