Ultra-low frequency high voltage generator (usually abbreviated as VLF, Very Low Frequency) is a "lightweight" artifact specifically designed for insulation withstand voltage tests on large-capacity power equipment (such as long-distance power cables, large generators, etc.).



Simply put, it is an efficient alternative to traditional power frequency (50Hz) withstand voltage test devices. Its core function is to generate high voltage at extremely low frequencies (usually 0.1Hz) to assess the insulation strength of these large-capacitance equipment, checking whether they can withstand overvoltages during operation.

⚡ Why use ultra-low frequency? (Core principle)

Traditional power frequency withstand voltage tests (50Hz) when testing long cables or large generators, due to the extremely large capacitance of the test object, require huge test currents and transformer capacity, making the equipment extremely heavy and expensive, and on-site handling and wiring are very difficult.

The principle of ultra-low frequency technology is very ingenious: according to the capacitive reactance formula Xc=1/(2πfC), when the test frequency f is significantly reduced, the capacitive reactance of the test object increases exponentially, and the required test current is greatly reduced.

Extreme lightweight: reducing the frequency from 50Hz to 0.1Hz theoretically reduces the required test power supply capacity to only one five-hundredth of that at power frequency. This greatly reduces the size and weight of the equipment, allowing one person to easily transport it to the site.

Good equivalence: Theory and years of practice have proven that 0.1Hz ultra-low frequency withstand voltage tests have equivalent sensitivity in detecting insulation defects (especially "water tree" aging in cross-linked polyethylene cables) compared to power frequency withstand voltage tests, and cause less damage to insulation.