Voltage levels and load capacity of ultra-low frequency high-voltage generators



Based on your previous understanding of "ultra-low frequency insulation withstand voltage tests," the ultra-low frequency high-voltage generator (VLF) is the core specialized equipment for executing this advanced test method. It is also known as a 0.1Hz ultra-low frequency high-voltage generator, a programmable ultra-low frequency high-voltage generator, or an ultra-low frequency withstand voltage tester.

Simply put, if the ultra-low frequency withstand voltage test is compared to a "physical examination plan," then the ultra-low frequency high-voltage generator is the "dedicated examination instrument" that implements this plan. Below is a detailed introduction to the core parameters, technical features, and applications of this equipment:

⚙️ Core Technical Parameters

The ultra-low frequency high-voltage generator uses digital frequency conversion technology to convert ordinary power frequency alternating current (220V/50Hz) into ultra-low frequency high voltage at a specific frequency. Its mainstream technical indicators are as follows:

Output frequency: The core frequency is 0.1Hz, and it usually supports multiple adjustable frequencies such as 0.05Hz, 0.02Hz, and even 0.01Hz.

Output voltage: Depending on the voltage level of the equipment under test, common peak voltages are divided into multiple levels such as 30kV, 50kV, and 80kV (some high-end models support custom higher voltages).

Load capacity: The lower the frequency, the larger the capacitive load the equipment can drive. For example, at 0.1Hz, it can typically carry a load of about 1.1μF, while at 0.02Hz, it can carry up to 5.5μF, which is sufficient to meet the testing needs of long-distance power cables.

Compliance with standards: It strictly adheres to the power industry standard "DL/T849.4-2004 General Technical Conditions for Ultra-Low Frequency High-Voltage Generators."

✨ Main Technical Features

Compared with traditional power frequency test transformers or series resonance devices, the ultra-low frequency high-voltage generator has extremely distinct advantages:

Extremely lightweight and portable, with strong field applicability: Theoretically, its required power supply capacity is only 1/500 of that of traditional power frequency equipment. This greatly reduces its size and weight (typically, the controller weighs only a few kilograms, and the booster weighs tens of kilograms), allowing a single person to carry it, making it very suitable for on-site operations in narrow spaces such as outdoor cable trenches and tunnels.

Fully automated intelligent control: It adopts microcomputer and digital frequency conversion technology, with the entire process of voltage boosting, voltage reduction, measurement, and waveform display automated. It is equipped with a large touch screen, simple to operate, and can display voltage, current, and output waveform in real time.

High-precision safety protection: It has a complete multi-level protection mechanism.

Overvoltage/overcurrent protection: The response time is extremely fast (usually less than 20ms), and the output is immediately cut off once the limit is exceeded.

No capacitive rise effect: It uses a high-low voltage closed-loop negative feedback control circuit to ensure accurate output voltage, unaffected by the capacitance of the test object.

Optoelectronic isolation control: The controller and the high-voltage boosting unit are connected via low-voltage signals, greatly ensuring the safety of operators.

Good equivalence and non-destructive: The 0.1Hz ultra-low frequency voltage can equivalently replace power frequency voltage to assess insulation strength, while the polarization current is extremely small, causing no cumulative damage to the insulation layer of cables or generators.