Extra-high voltage reference capacitor

Abstract

The present invention is an ultra-high voltage standard capacitor, which is an upright structure in which both the high-voltage electrode and the low-voltage electrode are fixed in the pressure vessel tank at the bottom with an insulating support, and overcomes the influence of the increase of the voltage level of the standard capacitor on the increase of its voltage coefficient. problem; for the field test structure, the present invention divides the standard capacitor into three independently sealed air chambers, which solves the inconvenient transportation problem of large-scale test equipment, so as to be used for field test and detection. When the present invention is used for UHV standard capacitors The insulation level is extremely high, the short-term power frequency voltage withstand capacity can exceed 1600kV, the long-term rated working voltage exceeds 1200kV, and the voltage coefficient is better than 2×10-6. The invention can also be used in the production of standard capacitors with a rated working voltage of less than 1600kV voltage level.

Description

technical field [0001] The invention belongs to high-voltage measuring equipment, and relates to an ultra-high voltage standard capacitor with a voltage level of 800kV to 1600kV, which is suitable for measuring the value of an ultra-high voltage standard capacitor, measuring the dielectric loss of an ultra-high voltage electrical equipment, calibrating the voltage division ratio of an ultra-high voltage divider, and Ultra-high voltage measurement fields such as voltage coefficient measurement of high-voltage standard voltage transformers. Background technique [0002] With the acceleration of my country's UHV power grid technology research and construction, the original high-voltage measurement equipment can no longer meet the needs. The precise measurement of capacitance and dielectric loss of UHV equipment, and the measurement of characteristic parameters of UHV metering equipment such as AC UHV standard voltage transformers all require standard capacitors with higher volt...

AI Technical Summary

Problems solved by technology

As the voltage level increases, the insulation distance between electrodes increases, and the height of low-voltage electrodes increases, resulting in extremely uneven local electric field distribution

At the same time, the torque of the low-voltage electrode of the cantilever beam structure increases, and the concentricity and coaxiality between the high-voltage electrode and the low-voltage electrode tend to shift, making the voltage coefficient of the standard capacitor (that is, the difference between the capacitance and the applied voltage amplitude The linear relationship) becomes worse and worse, leading to the expansion of the uncertainty of the precision measurement of the capacitance and dielectric loss of the test product

At present, the highest nominal voltage level of commercialized inverted structure standard capacitors in the world is 1200kV, but the actual working voltage under normal conditions should not exceed 800kV, otherwise many conditions need to be added, such as strict relative humidity of the environment, and extremely slow applied voltage , the harmonic content of the power supply is strictly controlled, etc.

In addition, the low-voltage electrode of an inverted standard capacitor is a cantilever beam structure. The shock generated by equipment transportation and on-site installation will easily lead to creep and bending of the cantilever support rod and tube, making it easy to shift between the low-voltage electrode and the high-voltage electrode, resulting in voltage coefficient further increase

With the increase of the voltage level and the increase of the size of the equipment, the difficulty of processing, installation, detection, adjustment and control of the concentricity and coaxiality between the electrodes of the inverted standard capacitor is also greatly increased.

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