Detection Technology
Composition of lightning impulse voltage generator
time：2025/9/18 source：Wuhan UHV reading：585 time
A lightning impulse voltage generator is a core equipment in high-voltage laboratories, used to simulate lightning overvoltages and test the insulation performance of electrical equipment (such as transformers, surge arresters, cables, etc.).
It primarily consists of the following core components:
1. Main Circuit Section
This is the heart of the generator, operating on the principle of the Marx Circuit, where multiple capacitors are charged in parallel and discharged in series to generate high voltage.
Charging Resistors (Rc): Limit the charging current to protect the rectifier power supply during charging; during discharge, they isolate the stages to ensure the capacitors effectively discharge in series.
Discharge Resistors (or Wave-Shaping Resistors): These include two key resistors:
Wavefront Resistors (Rf): Primarily used to adjust the wavefront time (the time taken for the voltage to rise from 0 to its peak). Reducing Rf shortens the wavefront time.
Wavetail Resistors (Rt): Primarily used to adjust the time to half-value (the time taken for the voltage to drop from its peak to half). Increasing Rt lengthens the wavetail time.
Main Capacitors (C): These are the energy storage units of the device. Multiple capacitors are charged in parallel to store electrical energy.
Triggered Spark Gaps (G): Act as controllable switches. After charging to a predetermined voltage, a triggering system causes them to break down, conducting the entire circuit and initiating the discharge process.
Stage Capacitors: In a multi-stage Marx generator, each stage has its own capacitor and spark gap.
2. Charging System
DC High-Voltage Power Supply: Typically a combination of a high-voltage rectifier stack and a transformer (voltage multiplier circuits are also common), used to provide stable DC high voltage to the main capacitors at each stage.
3. Triggering System
Triggering Device: This is the "ignition switch" of the generator. It produces a very high-amplitude, fast-rising pulse voltage to precisely break down the first-stage spark gap, thereby initiating the series discharge of the entire generator. It usually consists of a small impulse generator and a three-electrode spark gap.
4. Measurement System
Voltage Divider: Due to the extremely high voltages generated (up to several million volts), they cannot be measured directly with ordinary instruments. A voltage divider (usually a resistive-capacitive type) reduces the high voltage to a measurable low level proportionally.
Measuring Instruments: Primarily high-voltage pulse oscilloscopes or digital recorders, used to capture, display, and record the low-voltage pulse waveform from the divider, and analyze key parameters such as the peak value, wavefront time, and wavetail time of the impulse voltage.
5. Auxiliary Components
Sphere Gaps: In addition to the triggered spark gaps, there is often a large output sphere gap at the end of the generator, sometimes used to protect the test object (from overvoltage) or to adjust the waveform.
Main Structure: Includes insulating columns (usually made of epoxy resin or ceramic) that support the entire structure and grading rings, used to prevent corona discharge and optimize electric field distribution, ensuring stable operation of the generator.
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