In the field of power equipment testing, DC withstand voltage test, as an important means of detecting the insulation strength of high-voltage electrical equipment, is increasingly receiving industry attention. Compared with AC withstand voltage testing, DC withstand voltage testing has the characteristics of lightweight testing equipment, minimal insulation damage, and easy detection of local defects in the equipment. However, how to scientifically and reasonably select high-voltage equipment for DC withstand voltage testing has become a practical problem faced by many power workers.
Selection requires comprehensive consideration of multiple factors
According to technical experts from Wuhan UHV Power Technology Co., Ltd., the correct selection of DC high-voltage generators is crucial for ensuring the accuracy of test results and the safety of equipment operation. The main factors affecting selection include the type, voltage level, and capacity of the tested equipment.
There are significant differences in the performance requirements of DC high-voltage generators for different types of power equipment. For example, the conductivity current test of valve type lightning arrester requires the equipment to stably output current at low voltage and have high current measurement accuracy; The DC withstand voltage test and leakage current measurement of power transformers require the equipment to provide sufficiently high voltage output and strong overload capacity to cope with the surge current caused by the inductance characteristics of transformer windings.
Accurately match equipment specifications according to voltage levels
The ZGF series DC high voltage generators provided by Wuhan UHV have multiple models, covering a wide voltage range from 60kV to 800kV. Choosing the appropriate equipment model based on the voltage level of the substation is the key to ensuring the effectiveness of the test:
The maximum test voltage for a 10kV substation is generally 47kV, and the ZGF-60/2 model can be selected;
The maximum test voltage of the 35kV substation is 105kV, corresponding to the ZGF-120/2 model;
The maximum test voltage for a 110kV substation is 192kV, and the ZGF-200/2 model can be used;
The maximum test voltage for a 220kV substation is 305kV, and the ZGF-400/3 model is a suitable choice;
Due to the maximum test voltage exceeding 400kV, the 330kV substation requires the selection of ZGF-800/10 type DC high voltage generator.
In terms of cable testing, the rated voltage of paper insulated cables is 3.6/6kV, and the DC test voltage is 17kV, suitable for ZGF-60/2 model; The DC test voltage for the 21/35kV cable is 105kV, corresponding to the ZGF-120/3 model; If the DC test voltage of the 26/35kV cable is 130kV, the ZGF-200/5 model can be selected.
Technological innovation enhances equipment performance
The Wuhan UHV ZGF series 直流高電圧発生器 adopts a high-frequency voltage doubling circuit, applies advanced PWM high-frequency pulse width modulation technology, closed-loop adjustment, and greatly improves voltage stability. The equipment has reliable overvoltage, overcurrent, and zero position closing protection functions, with a 0.75 times voltage switching function. It is mainly suitable for power departments, industrial and mining, metallurgy, steel and other enterprises' power departments to conduct DC withstand voltage tests or DC leakage current tests on high-voltage electrical equipment such as zinc oxide lightning arresters, power cables, transformers, circuit breakers, generators, etc.
In terms of equipment technical parameters, the voltage accuracy and current accuracy are both ± (1.0% reading+2 words), the ripple factor is ≤ 0.5%, and the voltage stability is ≤ 1% when the power supply voltage changes by ± 10%. The no-load voltage can exceed the rated voltage by 10% and be used for 10 minutes, with a maximum charging current of 1.25 times the rated current.
Wide prospects for industry applications
The application of DC high-voltage generators in the power industry is becoming increasingly widespread, mainly used for DC withstand voltage testing and leakage current measurement of high-voltage electrical equipment such as power transformers, zinc oxide lightning arresters, and power cables. Wuhan UHV, as a leader in the high-voltage electrical measurement industry, has been meticulously cultivated for nearly 22 years, and its products are widely used in the maintenance and testing of power systems.
In the future, DC high-voltage generators will pay more attention to intelligence and automation, and the equipment will have higher testing accuracy and stability, while integrating more intelligent monitoring and data analysis functions, providing more comprehensive support for the maintenance and management of power equipment.
