The impulse voltage test is one of the basic items in high-voltage tests for electrical equipment. After the design, manufacture, and repair of electrical equipment, it is required to conduct impulse tests to verify or inspect the equipment. Common electrical equipment includes power transformers, power transformers, high-voltage switches, combined electrical apparatus, lightning arresters, power cables and accessories, bushings, and insulators, all of which need to undergo impulse tests.
The impulse voltage test is also one of the basic items in high-voltage test research. In many aspects such as insulation coordination research, electromagnetic compatibility research, and discharge mechanism research, impulse voltage tests are required.
Therefore, impulse voltage test equipment has wide applications in factories, research institutions, and universities’ high-voltage test laboratories, where different specifications of impulse test equipment can be seen.
Principle of impulse voltage test:
Impulse voltage is a single transient process, so the impulse voltage test has different requirements for three test quantities: voltage amplitude, voltage waveform, and voltage frequency.
1. Voltage amplitude: For different test items and different test requirements, corresponding impulse voltage amplitudes should be applied. The amplitude of impulse voltage can be adjusted by controlling the charging voltage of the impulse voltage generator, which is easy to understand. It should be noted that the corresponding relationship between impulse voltage amplitude and charging voltage is: UP = UC * n * η, where UP: impulse voltage amplitude, UC: charging voltage of the impulse voltage generator (each level), n: number of levels used by the impulse voltage generator, η: efficiency of the impulse voltage generator.
2. Voltage waveform: The commonly used waveforms in impulse voltage tests include standard lightning impulse waveforms, wave tail cut-off standard lightning impulse waveforms, standard operating impulse waveforms, steep waveforms, and other special waveforms. The definition of waveform parameters can be referred to the provisions of GB/T16927 “High Voltage Test Technology”. It should be particularly noted that the output waveform of the impulse voltage test circuit is closely related to the connection of the test item, components of the test equipment, and the distance to the surrounding grounding body. Therefore, the difficulty of the impulse test and most of the work are related to wave adjustment. Whether a satisfactory impulse waveform can be obtained is the key to the impulse test. Usually, waveform adjustment refers to adjusting the wavehead time and wave tail time of the impulse waveform. For cut-off tests, the cut-off time should be adjusted, and for steep wave tests, the steepness of the waveform should be adjusted.
3. Voltage frequency: After determining the voltage amplitude and voltage waveform, the remaining work is to determine the number of times to apply the voltage. It should be noted that impulse voltage waveforms have positive and negative polarities, and the number of charging times under each polarity should be clearly defined. Also, the interval time between each voltage application should be considered.
Post time: Aug-25-2026