With the continuous improvement of voltage levels in the power system, GIS (gas insulated metal enclosed switchgear) has been widely used in substation construction due to its advantages of small footprint and high operational reliability. However, the insulation performance testing of GIS equipment has always been a focus of industry attention. The series resonant withstand voltage test, as a core method for insulation performance testing of high-capacity capacitive equipment such as GIS, is receiving increasing attention from power units. So, how to choose a suitable AC resonance testing system?

Clarifying the voltage level and capacity requirements is the first step in selection

Wuhan UHV Technology points out that when selecting a GIS AC resonance testing system, the range of the device should be determined based on the highest voltage level of the equipment under the jurisdiction of the unit. GIS equipment has a wide range of voltage levels, ranging 110kV to 1000kV ultra-high voltage. Different voltage levels have completely different requirements for the output voltage and capacity of the testing device. Experts emphasize that the specifications required for 10kV distribution networks and 110kV substations are completely different, and accurate calculation of the capacitance value of the test sample and the required test voltage must be carried out before selection.

Wuhan UHV can provide series resonant devices with rated capacities ranging 75kVA to 10000kVA and above, and rated voltages ranging 25kV to 800kV (customizable), which can meet diverse testing needs distribution networks to UHV projects. The UHV series variable frequency series resonant AC withstand voltage device is a star product in the industry, mainly used for AC withstand voltage testing of cross-linked cables, hydroelectric generators, main transformers, busbars, GIS and other equipment.

Pay attention to technical parameters and performance indicators

After determining the voltage level and capacity, attention should also be paid to the technical parameters and performance indicators of the device. A high-quality GIS AC resonance testing system should have stable sine wave voltage output and waveform distortion rate below 1.0%. In addition, the quality factor (Q value), operating frequency range, frequency modulation accuracy, and other parameters of the device directly affect the accuracy and efficiency of the experiment.

The series resonant device of Wuhan UHV adopts advanced DSP platform technology, equipped with DSP+FPGA dual chip architecture, and calculates the load capacitance change in real time through dynamic frequency tracking algorithm to control the resonant frequency error within ± 0.05Hz. It adopts imported specialized SPWM digital waveform generation chip and advanced IPM module to ensure good output voltage waveform. The device can accurately match the capacitance parameters of the test sample within 10 seconds, and the voltage fluctuation rate is controlled below 1%.

It is worth mentioning that the capacitance difference between GIS equipment and power cables can reach more than 10 times, and a targeted configuration scheme for series resonant voltage withstand devices needs to be selected. The products of Wuhan UHV support ultra wide range testing 10kV to 1000kV, and are compatible with various power equipment such as transformers, cables, transformers, GIS, etc., fully meeting the latest standards of State Grid and Southern Power Grid.

Equipment composition and configuration cannot be ignored

A complete series resonance test device consists of core components such as variable frequency control power supply, excitation transformer, high-voltage reactor, and capacitive voltage divider. The variable frequency control power supply is the "brain" of the device, outputting an adjustable frequency of 30-300Hz and automatically tracking the resonance point; High voltage reactors are the "resonant core" and form a resonant circuit with the tested capacitor; The capacitive voltage divider is a "precise ruler" that measures the high voltage side voltage in real-time.

When selecting, it is necessary to ensure that the quality and performance of each device component meet the requirements. For small capacity samples, compensation capacitors can also be selected to expand the applicability of the device. In addition, the volume, weight, and ease of handling of the equipment should be considered to adapt to the actual working environment of the power sector and industrial and mining enterprises.

Security protection and after-sales service are equally important

Safety is always the top priority of high-voltage testing. Experts remind that when choosing a GIS AC resonance testing system, priority should be given to products with comprehensive safety protection functions, such as overvoltage protection, overcurrent protection, short circuit protection, zero start, system detuning (flashover) protection, etc.

The series resonant device of Wuhan UHV has multiple protection mechanisms, which can effectively avoid the risks caused by misoperation. When the weak point of the insulation of the test sample is broken down, the circuit current rapidly decreases, and there will be no large short-circuit current burning the fault point, and there is no overvoltage recovery phenomenon, effectively protecting the test sample and equipment.

In addition, the manufacturer's after-sales service and technical support capabilities are also important considerations for selection. It is understood that Wuhan UHV has a professional after-sales service team that can provide timely and professional technical support and solutions for users.

When selecting a GIS AC resonance testing system, it is necessary to comprehensively consider multiple aspects such as voltage level, capacity requirements, technical parameters, safety protection, equipment configuration, and manufacturer services. By comprehensively comparing the performance and prices of different products and selecting the most cost-effective product that meets actual needs, we can provide solid guarantees for the safe and stable operation of the power system.