DC High Voltage Generator



(commonly known as "DC Hipot") is a specialized test equipment capable of producing continuously adjustable DC high voltage starting from zero volts.

Combined with the series resonant frequency conversion device, ultra-low frequency withstand voltage test, and zinc oxide arrester tester you learned about earlier, the DC high voltage generator plays another extremely important role in power preventive tests. If series resonance and ultra-low frequency are mainly used to assess the insulation "withstand voltage" strength of equipment, then the DC high voltage generator is more adept at detecting insulation defects and "leakage" conditions.

The following is a detailed analysis of the core principles, technical features, and applications of the DC high voltage generator:

⚡️ Core Working Principle

The core task of the DC high voltage generator is to convert ordinary power frequency AC (220V/50Hz) into high-quality, highly stable DC high voltage. Its technical route has mainly undergone the following evolution:

Traditional power frequency voltage doubling rectification: Early equipment was bulky, obtaining DC high voltage by stepping up through a power frequency transformer and then rectifying and filtering.

Modern medium-high frequency voltage doubling rectification (mainstream technology): Modern portable DC hipots generally adopt PWM (Pulse Width Modulation) technology and high-power IGBT devices. It first inverts the power frequency AC into medium-high frequency AC of several kilohertz to tens of kilohertz, then steps it up through a medium-high frequency transformer and uses a voltage doubling rectifier circuit to obtain DC high voltage.

This "high-frequency inversion-voltage doubling rectification" technical route greatly reduces the size and weight of the transformer, enabling the equipment to be miniaturized and lightweight, while the output DC voltage has extremely low ripple coefficient and extremely high stability.

⚙️ Core Test Functions

The DC high voltage generator is mainly used to conduct the following two types of key tests on high-voltage electrical equipment:

DC withstand voltage test: Apply DC high voltage higher than its rated voltage to the equipment to assess its insulation strength under DC voltage and determine whether there are local defects in the insulation.

Leakage current test: During the application of DC high voltage, precisely measure the tiny current flowing through the insulation inside the test object. The magnitude of the leakage current and its variation with voltage and time are important bases for judging whether the insulation is damp, dirty, or aged.

✨ Main Technical Features

Modern intelligent DC high voltage generators have the following notable features:

Portable and stable output: Adopting integrated or split portable design, the weight is usually only a few kilograms to over ten kilograms, making it very convenient for on-site handling. The output voltage stability is high, and the ripple coefficient can usually be controlled below 0.5% or even 0.2%, ensuring accurate test data.

Intelligent and automated: Many new devices adopt AIPWM (Artificial Intelligence Pulse Width Modulation) technology and have fully automatic test modes. For example, for zinc oxide arresters, it can automatically complete boosting, finding the 1mA reference voltage (U1mA), automatically reducing voltage and measuring the leakage current at 0.75 times U1mA with one click, without manual intervention.

Comprehensive safety protection: Built-in multiple protection functions, including overvoltage protection, overcurrent protection, zero-position start protection, poor grounding protection, and disconnection protection. Once an abnormality is detected, the high-voltage output can be quickly cut off within microseconds to ensure the safety of personnel and equipment.

Convenient data management: Equipped with a large-screen LCD display, it can display parameters such as voltage, current, and time in real time. Built-in perpetual calendar supports storage of test data, on-site printing, and export, facilitating subsequent file management.