VLF AC cable hipot tester
Model:XHDP-30(use for 10KV cable)
Model:XHDP-50(use for 50KV generator)
Model:XHDP-80(use for cable with 35KV and below voltage level)
Ultra low frequency insulation withstand voltage test is actually an alternative method of power frequency withstand voltage test. We know that when the power frequency voltage withstand test is carried out on large generators, cables and other test objects, because their insulation layer presents a large capacitance, a large capacity test transformer or resonant transformer is required. Such huge equipment is not only bulky and expensive, but also inconvenient to use.
In order to solve this contradiction, the power department has adopted reducing the test frequency, thereby reducing the capacity of the test power supply.
Many years of theory and practice at home and abroad have proved that using 0.1Hz ultra-low frequency voltage withstand test instead of power frequency voltage withstand test can not only have the same equivalence, but also greatly reduce the volume and weight of the equipment. Theoretically, the capacity is about one five-hundred of power frequency, and the operation is simple, which has more advantages than power frequency test.

This VLF AC Hipot Tester combines modern digital frequency conversion advanced technology, adopts microcomputer control, and is fully automated in voltage rise, voltage drop, measurement and protection. Because it is fully electronic, it has small volume, light weight, large screen LCD display, clear and intuitive, and can display the output waveform and print the test report.
The design index fully conforms to the power industry standard of "general technical conditions for special testing instruments for power equipment, Part 4: General technical conditions for ultra-low frequency and high voltage generators", which is very convenient to use.
At present, mechanical methods are used at home and abroad to modulate and demodulate ultra-low frequency signals, so there are non-standard sine wave waveforms, large measurement errors, spark discharge in the high-voltage part, and the equipment is bulky. Moreover, the second and fourth quadrants of sine wave also need high-power high-voltage resistors for discharge shaping, so the overall power consumption of the equipment is large. This product can overcome these shortcomings and has the following characteristics:
The ultra-low frequency with rated voltage less than or equal to 50kV adopts single connection structure (a booster); The ultra-low frequency greater than 50kV adopts a series structure (two boosters are connected in series), which greatly reduces the overall weight and enhances the carrying capacity. Moreover, the two boosters can be used as ultra-low frequency of low voltage level alone.
Current, voltage and waveform data are directly sampled from the high voltage side, so the data is accurate.
It has overvoltage protection function. When the output exceeds the set voltage limit, the instrument will stop for protection, and the action time is less than 20ms.
It has over current protection function: it is designed as high and low voltage dual protection, and the high-voltage side can be accurately shut down for protection according to the set value; When the current at the low-voltage side exceeds the rated current, shutdown protection will be carried out, and the action time is less than 20ms.
The high-voltage output protection resistor is designed in the booster body, so there is no need to connect another protection resistor outside.
Due to the use of high and low voltage closed-loop negative feedback control circuit, the output has no capacity rise effect.