Main Applications
This device is mainly used for the following purposes:
1. AC withstand voltage testing of 6kV-500kV high-voltage cross-linked cables
2. Power frequency withstand voltage testing of 6kV-500kV transformers
3. AC withstand voltage testing of GIS and SF6 switchgear
4. AC withstand voltage testing of generators
5. AC withstand voltage testing of other high-voltage power equipment such as busbars, bushings, and instrument transformers.
This complete set of equipment consists of a variable frequency power supply, excitation transformer, reactor, and voltage divider.
Equipment Introduction
It is composed of a variable frequency power supply, excitation transformer, high-voltage reactor, and capacitive voltage divider. The capacitance of the test object and the reactor form a series resonant connection; the voltage divider is connected in parallel with the test object to measure the resonant voltage across it and provide overvoltage protection signals; the frequency-modulated power output is coupled to the series resonant circuit through the excitation transformer to provide the excitation power for series resonance. Shanghai Dafan specializes in R&D and production, adopting a modular design that greatly reduces labor intensity.
Product Aliases
Variable frequency series resonant AC withstand voltage test device, variable frequency series resonance, variable frequency series resonance, series resonance, frequency-tuned series resonance, series resonant withstand voltage test device, series resonant test equipment, cable withstand voltage test device, power frequency withstand voltage test device, high-voltage cross-linked cable AC withstand voltage test equipment, AC withstand voltage test device, frequency-tuned resonance, frequency-tuned series resonant AC withstand voltage test device, AC series resonance, AC variable frequency series resonance, variable frequency resonance, variable frequency series resonance, series resonance test device, series resonance withstand voltage device, GIS AC withstand voltage test device, generator power frequency (AC) withstand voltage test device, motor power frequency (AC) withstand voltage test device, transformer power frequency (AC) withstand voltage test device, etc.
Current Status Analysis
Why do relevant domestic and international authorities widely recommend replacing DC withstand voltage with AC withstand voltage? With the development of the national economy and the increase in voltage levels of urban power supply networks, cross-linked polyethylene insulated power cables (XLPE) are being used more and more widely both domestically and internationally due to their reasonable process and structure, excellent electrical performance, and safe and reliable operation characteristics. Especially in the field of high-voltage power transmission, significant progress has been made. Compared with oil-filled cables, cross-linked cables are easier to lay and install, simpler to operate and maintain, and do not have the problem of oil leakage. However, recent years of operation and research have shown that the insulation of XLPE cables is prone to treeing discharge during operation, causing insulation aging and damage, which seriously affects the service life of XLPE insulated power cables. Therefore, fully understanding the insulation characteristics of cross-linked cables and timely and effectively detecting and preventing certain defects in the insulation are of great significance for ensuring the safe operation of equipment and even the entire system. This paper elaborates on the main factors affecting the insulation of cross-linked cables and the principles of cable acceptance tests, and concludes that it is necessary and feasible to conduct AC withstand voltage tests on cross-linked cables on site. To ensure the safe and reliable operation of cables, relevant international standards have clearly stipulated various tests for cables. The main test items include: measuring insulation resistance, DC withstand voltage, and leakage current. Among them, measuring insulation resistance is mainly to check whether the cable insulation is aged, damp, or has insulation defects exposed during the withstand voltage test. DC withstand voltage and leakage current tests are carried out simultaneously, with the purpose of detecting defects in the insulation. However, in recent years, domestic and international test and operation experience has proven that DC withstand voltage tests cannot effectively detect insulation defects in cross-linked cables and may even cause insulation hazards. In Germany, Sechiswag Company conducted tests on 41 circuits of 10 kV XLPE cables from 1978 to 1980, and 87 faults occurred; in Sweden, more than 9,000 km of 3 kV to 24.5 kV XLPE cables were put into operation, and 107 faults occurred. Domestically, cable accidents have also occurred multiple times, and a considerable number of cable faults are caused by the negative effects of frequent DC withstand voltage tests. Therefore, relevant domestic and international authorities widely recommend replacing traditional DC withstand voltage with AC withstand voltage. From the 1980s to the mid-1990s, advanced countries such as Canada, Germany, and the United States formulated corresponding AC withstand voltage test standards and promoted their application. Since the late 1990s, regions in China such as Guangdong, Beijing, Shanghai, Zhejiang, and Shandong have issued interim regulations for AC testing of XLPE cables. The national standard GB50150-2006 "Standard for Handover Test of Electrical Equipment Installation Engineering" recommends the use of variable frequency series resonant withstand voltage testing.
Product Features
1. One of the few in the country to pass the strict type test appraisal by the national authoritative department - the Electric Power Industry Electrical Equipment Quality Inspection and Testing Center (Wuhan High Voltage Research Institute), ensuring reliable quality and the safety of test personnel, test objects, and test equipment itself;
2. In the 2008 national equipment competition organized by Northeast Electric Power Research Institute, it passed all test items in one go, being the only one to meet all national standard requirements including the 60-minute temperature rise, and again ranked among the top in the competition;
* Recognized by many professional customers for its excellent quality and professional service (such as Guangxi Electric Power Research Institute, Hulunbuir Electric Power Bureau, Qiqihar Electric Power Bureau, China Water Resources and Hydropower Sixteenth Engineering Bureau, China Chemical Group, etc.)
* Small size, light weight, especially suitable for on-site use;
* All main components are imported from world-renowned enterprises, including Texas Instruments and Intel from the United States, Siemens and Schneider from Germany, Toshiba and Fuji from Japan, ensuring stable and reliable performance;
* Comprehensive and reliable overvoltage, overcurrent, discharge, overtemperature, and zero-start protection, with an action time of 1 microsecond;
* The equipment comes with a built-in micro printer, which can promptly print and save test data;
* Designed with military-standard vibration resistance and dustproofing, able to withstand long-distance transportation and harsh operating environments;
* One-key mouse-style knob "foolproof" operation, with a large-screen LCD display;
* Unique software calibration function, convenient for users to calibrate meters, ensuring high voltage value accuracy;
* German Rittal design all-aluminum alloy chassis, dual-use for vertical and horizontal placement, lightweight and beautiful, greatly facilitating on-site use;
* Committed to promises, professional and timely service, making every effort to serve customer needs;
* The product is stable and reliable, with a three-year warranty (ten-year warranty for the main unit) and lifelong maintenance;
