Technical characteristics of composite insulated capacitive voltage divider

Author： GOZ Electric Time：2024-05-12 09:28:02 Read：14

1) High accuracy. The accuracy can reach 0.1/0.2 level. This is mainly due to the following characteristics of high-voltage capacitors and low-voltage capacitors: ① Using a metallized film structure, the medium and electrodes are integrated without gaps, and the capacitance temperature coefficient has good stability; ② High-voltage capacitors and low-voltage capacitors use the same medium and the same outer diameter The same parameters are matched, so its temperature characteristics have good consistency and the voltage division ratio error band range is small; ③ The high-voltage capacitor adopts a large end face structure design to reduce contact resistance and increase flow capacity, so that the operating temperature rise of the capacitor is very small , generally only about 1℃; ④ The low-voltage capacitor has a large capacitance ratio, and a low-voltage output of 6.5/√3 V can be obtained by dividing the voltage once in series. Therefore, the cumulative error is small.

2) High insulation. ① Both high-voltage and low-voltage capacitor insulation has self-healing characteristics and is a dry cylinder with uniform electric field distribution inside and on the end face; ② The capacitor units inside the voltage divider are installed and arranged scientifically and reasonably, effectively avoiding edge breakdown and surface flashover. network phenomenon. 3) The working field strength and current density of the high-voltage capacitor dielectric are designed reasonably, and the production process is rigorous, thus effectively ensuring the stability of the capacitance during long-term operation of the voltage divider.

4) Because it adopts a metallized film structure, it is easy to burn out and form an open circuit after breakdown, and will not cause short circuit failure.

5) Comply with environmental protection requirements, no oil, no SF6, eliminate fire,

It completely eliminates the hidden danger of environmental greenhouse effect and is easy to maintain.

Design and process points of main components of composite insulated capacitor voltage divider

1. Design and process points of high-voltage and low-voltage capacitor units

The high voltage of CVT is mainly borne by the capacitive voltage divider. The voltage resistance strength of the capacitor medium is crucial not only for the reliable operation of the equipment but also for the accuracy of voltage measurement. In EVT, the high voltage is entirely borne by the voltage divider. bear. Whether it is a capacitor with organic or inorganic materials as the dielectric, the use of metallized electrodes eliminates the influence of the air gap between the dielectric and the plate, which helps to improve the temperature stability of the capacitor. Therefore, high-voltage and low-voltage capacitors adopt self-healing structures. Design, and in order to suit environmentally friendly requirements, a dry structure was chosen.

2. Design of high-voltage capacitor unit

1) Selection of insulation medium. Selection of dielectric material and field strength of capacitive voltage divider...

2) Metalized PP membrane structure design. ①Adopt inner string structure, generally using 5 to 13 inner strings. ②Plating and square resistance. According to the AC characteristics of capacitance stability, zinc/aluminum alloy is selected as the coating for the electrode. The self-healing energy is proportional to the square resistance of the electrode. When the electrode resistance is constant, the electrode area cleared by self-healing is proportional to the self-healing energy. The greater the self-healing energy, the greater the electrode area evaporated during the self-healing process. big. Obviously, the selection of square resistance should not only help improve the insulation level and capacity stability, but also benefit the oxidation resistance and reduce the operating temperature rise.

3) Selection of insulating heat shrink tubing. Use electrician high-voltage heat shrink tubing with a thickness of 1 mm, a heat shrink temperature of 90 ℃ ~ 115 ℃, and an operating temperature of -40 ℃ ~ +80 ℃.

4) Selection of insulation sealing materials. Epoxy resin that can absorb discharge at the tip (spray gold burr) should be used, with good sealing performance and an operating temperature of -40 ℃ ~ +80 ℃.