A transformer is a special transformer, which is a connecting element between the primary system and the secondary system, providing AC voltage and current data to secondary equipment such as measurement, protection and automatic devices. When the power system transmits electric energy, it is usually transmitted by AC voltage and high-current loops, and cannot be directly measured by meters. The transformer transmits the information of high voltage and high current of the power grid to the measuring instrument, relay protection and automatic device on the secondary side of low voltage and small current, and its primary winding is connected to the power grid, and the secondary winding is connected with the measuring instrument and protection device respectively. The transformer works with measuring instruments and metering devices to measure the voltage, current and electrical energy of the primary system; In conjunction with relay protection and automatic devices, it can constitute electrical protection and automatic control of various faults in the power grid.
Routine testing items of transformer
The transformer is mainly divided into two categories in terms of use: metering and protection, and can be divided into current transformer (CT) and voltage transformer (PT) according to the actual application. The main inspection items are as follows: insulation resistance and withstand voltage test: CT and PT basic test.
PT's unique voltage transformation ratio measurement (including the intermediate transformer of capacitive voltage transformer), test methods such as voltage method, ratio bridge method, etc.
Measurement of dielectric dissipation factor and capacitance of electromagnetic voltage transformer.
CT unique test items such as variable ratio test, test methods such as current method, voltage method, CT variable ratio tester test (transformer volt-ampere characteristic tester).
CT primary winding AC withstand voltage test.
CT excitation characteristics (volt-ampere characteristics) curves.
The common method to verify the correctness of the overall wiring of the secondary circuit of the transformer is the co-current pressurization test of the transformer, which finds out the wiring problem of the secondary circuit of the transformer through the test, and locks the fault location, which is convenient for the analysis, troubleshooting and treatment of the fault. The transformer can be tested from the primary terminal through the current, the pressure test or the secondary circuit through the current and pressure test.
Transformer testing technology
Wuhan Halma PowerWith 10 years of experience in CTP application, we have developed a high-precision transformer excitation characteristics, ratio and polarity tester based on low-frequency frequency conversion technology by adopting the latest generation of electronic technology. CTP-220 Transformer TesterIt covers most of the tests required for CT and PT, and can meet the various tests of laboratory and field transformers under different testing needs.
The traditional test of CT PT volt-ampere characteristic curve and 10% error curve uses power frequency 50Hz and 3000V voltage output, which is cumbersome and inconvenient to carry. CTP-220 adopts frequency conversion method, which can complete the CT test of the inflection point voltage of 50,000 volts and the primary current of up to 10,000 amperes, which basically covers all types of current (such as: protection, metering, TPY, TPX, casing CT, etc.) and comprehensive testing of various voltage levels PT, with a test accuracy of up to 005%。
CTP-220 Configuration 64-inch true color TFT screen, the panel can intuitively display the primary and secondary wiring diagrams of various types of CT and PT tests, built-in Linux operating system, the function menu can choose DC resistance, excitation, conversion ratio, load and other test items, after the test is completed, you can directly print the transformation ratio, polarity, phase, angle difference, ratio difference, inflection point voltage and other data reports. Since the launch of the first transformer tester based on the frequency conversion method in 2008, Wuhan Halma Power has carried out product iteration and update in line with the needs of the industry, improved product performance, and upgraded the product system, which has won high recognition from domestic and foreign power system substation maintenance units, related power installation engineering companies, large transformer manufacturers and other users. In the future, we will continue to strengthen investment in technology research and development and product field expansion, keep up with the development trend of the industry, and strive to provide users with better services and experience.