Why do relevant departments at home and abroad widely recommend replacing DC withstand voltage test with AC withstand voltage test? With the development of the national economy and the increase in the voltage level of urban power supply, cross-linked polyethylene insulated power cables (XLPE) have been increasingly widely used at home and abroad due to their reasonable process and structure, excellent electrical performance, and safe and reliable operation characteristics. Especially in the field of high-voltage transmission, great progress has been made. Compared with oil-filled cables, XLPE 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 tree-like 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 XLPE cables and timely and effectively discovering and preventing certain defects in the insulation are of great significance for ensuring the safe operation of equipment and even the system. This article elaborates on the main factors affecting the insulation of XLPE cables and the principle of cable handover tests, and believes that it is necessary and feasible to conduct AC withstand voltage tests on XLPE 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 aging, damp, or has insulation defects exposed during the withstand voltage test. The DC withstand voltage and leakage current tests are carried out simultaneously, aiming to discover defects in the insulation. However, in recent years, tests and operating experience at home and abroad have proven that DC withstand voltage tests cannot effectively discover insulation defects in XLPE cables, and may even cause hidden dangers to the cable insulation. In Germany, Sechiswag Company had 87 faults in 41 circuits of 10 kV XLPE cables from 1978 to 1980; in Sweden, more than 9,000 km of 3 kV to 24.5 kV XLPE cables were put into operation, with 107 faults. Domestically, cable accidents have also occurred many times, and a considerable number of cable faults are caused by the negative effects of frequent DC withstand voltage tests. Therefore, relevant departments at home and abroad 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, Guangdong, Beijing, Shanghai, Zhejiang, Shandong and other places in China have issued interim regulations for AC tests on XLPE cables. The national standard GB50150-2006 "Standard for Handover Test of Electrical Equipment Installation Engineering" recommends the use of variable frequency series resonance withstand voltage method.

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), with reliable quality, ensuring the safety of test personnel, the tested object, and the test equipment itself;

2. In the 2008 national equipment competition organized by Northeast Electric Power Research Institute, it passed all test items at once, being the only one to meet all national standard requirements including the 60-minute temperature rise, and ranked among the top again in the competition results;
* With excellent quality and professional service, it has gained recognition from many professional customers (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 protection against overvoltage, overcurrent, discharge, overheating, and zero-start, 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 dust prevention, suitable for long-distance transportation and harsh operating environments;
* One-key mouse-style knob "foolproof" operation, with large-screen LCD display;
* Unique software calibration function, convenient for users to calibrate meters, ensuring the accuracy of high voltage values;
* German Rittal design all-aluminum alloy chassis, can be placed horizontally or vertically, lightweight and beautiful, greatly facilitating on-site use;
* Keep promises, provide professional and timely service, and do our best 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;