Wuhan UHV specializes in producing series resonance (also known as cable withstand voltage test equipment). Next, we will share with you the composition and selection of cable withstand voltage test equipment.

Overview and Basic Components of Series Resonance

Firstly, let's talk about the purpose of series resonance. Series resonance is an indicator requirement for insulation inspection of large capacity and high voltage power equipment in power preventive testing projects. It is achieved by adjusting inductance and frequency in combination to achieve the function of resonant boosting. Variable frequency series resonance is composed of a control power supply, excitation transformer, high voltage reactor, compensation capacitor, and capacitive voltage divider. Before purchasing, we need to understand the basic situation on site. For example, for power cables, we need to know the length and cross-sectional area of the cable in advance, calculate the maximum capacitance of the test subject based on these known conditions, and then calculate the design capacity of the series resonance device based on the known electrical parameters. Today, Huatian Power has designed a series resonance device based on our previous design. The practical operational experience of the solution and after-sales department, Share with everyone the conventional configuration scheme for cable series resonance.

Selection guide for series resonance of power cables

Taking 10kV cables as an example: First, we need to review the preventive testing regulations for electricity. The standard test voltage for 10kV high-voltage cables is 2U0 or 2.5U0. Here, we need to obtain two terms, "phase voltage" and "line voltage", which have a relationship of 1.732 times. The phase voltage of 10kV cables is 8.7kV, multiplied by 2.5 times, which equals the highest voltage value. Of course, there are also cases where double the voltage is applied, depending on the actual situation on site. The next step is to calculate the resonant frequency. With a cable length of 300mm2 not exceeding 3.0km, the corresponding capacitance after calculation is 1.13 μ F, F resonant frequency=1/6.28 × √ 20.75 × 1.13 × 10-6.=33Hz, maximum test current at 33Hz=33 × 6.28 × 1.13 × 10-6 × 22 × 103=5.15A; if the single section voltage of the reactor is 22kV and the current is 2A, According to the characteristics of parallel circuits, the voltage remains constant, and the current is added together, which means that the withstand voltage test of the current cable can be achieved by connecting three reactors in parallel.