By hvhipot 
The lightning impulse voltage tester under HV Hipot Electric Co., Ltd. power can help many power workers conduct various power tests more conveniently.
Its core working principle is “parallel charging, series discharging”.
1. Charging stage:
The high-voltage DC power supply slowly charges all stage capacitors (C1, C2,…) in parallel to the same voltage U ₀ through isolation resistors.
At this point, the energy stored in each capacitor is half CU ₀ ². As it is connected in parallel, the total charging voltage is U ₀, but the total energy stored is the sum of the energy stored in each capacitor.
2. Trigger and discharge stage:
When the first gap (ignition gap) is triggered by an external system or overvoltage breakdown, the process begins.
The voltage on the upper plate of the first stage capacitor C1 suddenly grounded, causing the voltage at both ends of the second stage ball gap to instantly rise from 0 to nearly 2U ₀ (because the voltage on the upper plate of C2 was originally U ₀, while the voltage on the lower plate instantly changed to – U ₀ due to the discharge of C1), far exceeding its breakdown voltage and immediately piercing through.
This process spreads rapidly like dominoes, with all the capacitors connected in series in an instant.
In the end, the voltage of all capacitors is superimposed, theoretically generating an instantaneous high voltage of up to n * U ₀ at the output terminal (n is a series), and discharging it to the test object and waveform adjustment resistor.
3. Waveform formation:
The discharge current flows through the wavefront resistor and the tail resistor. By adjusting the resistance values of these two resistors, the waveform of the output impulse voltage can be accurately controlled to meet the standard requirements.