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 circuit breakers
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 resonance connection; the voltage divider is connected in parallel with the test object to measure the resonance voltage on the test object and serve as an overvoltage protection signal; the frequency-modulated power output is coupled to the series resonance circuit through the excitation transformer, providing excitation power for the series resonance. Shanghai Dafan specializes in R&D and production, adopting a modular design to greatly reduce labor intensity.
Product Aliases
Variable frequency series resonance AC withstand voltage test device, variable frequency series resonance, variable frequency series resonance, series resonance, frequency-modulated series resonance, series resonance withstand voltage test device, series resonance 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-modulated resonance, frequency-modulated series resonance 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 Situation Analysis
Why do relevant domestic and international authorities widely recommend using AC withstand voltage instead of DC 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 operation and research have shown that the insulation of cross-linked polyethylene 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 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 principle of cable handover tests, and believes that it is necessary and feasible to implement 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, aiming to detect 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. The German company Sechiswag 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 occurring; 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 using AC withstand voltage instead of traditional DC 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 conducting 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), ensuring reliable quality and the safety of test personnel, test objects, and the test equipment itself;
2. In the 2008 national equipment competition organized by the 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 ranked among the top again in the competition results;
* With excellent quality and professional service, it has gained the recognition of 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 major components are imported from world-renowned enterprises, including Texas Instruments, Intel, Siemens, Schneider, Toshiba, Fuji, etc., ensuring stable and reliable performance;
* Comprehensive and reliable protection against overvoltage, overcurrent, discharge, overheating, and zero-start protection, with an action time of 1 microsecond;
* The equipment comes with a built-in micro printer, which can print and save test data in a timely manner;
* Designed with military-standard anti-vibration and dustproof features, resistant to long-distance transportation and harsh usage 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 the accuracy of high voltage values;
* All-aluminum alloy chassis designed by Rittal, suitable for both vertical and horizontal use, lightweight and beautiful, greatly facilitating on-site use;
* Keep promises, provide professional and timely service, and strive to meet customer needs;
* The product is stable and reliable, with a three-year warranty (ten-year warranty for the main unit), and lifelong maintenance;
