The CVDN series nitrogen based environmentally friendly capacitive voltage divider is mainly used in the field of voltage transformers, providing voltage division for important components in 35KV to 1000KV smart grid digital substations - electronic voltage transformers (EVT) and optoelectronic voltage transformers (OVT).

Having the technical level of GE in the United States, ABB in Sweden and Switzerland, and other similar products
At present, in the world's power system, most of the capacitive voltage dividers used in capacitive voltage transformers (CVTs) use aluminum foil electrodes, oil immersed or SF6 gas insulated types. The inherent disadvantages of these products are ("three lows", "three haves"):
1. Low accuracy: The capacitance temperature characteristics are inconsistent and have large drift. Medium voltage high, in order to meet the input requirements of EVT and OVT, multiple voltage dividers are used, resulting in irregular and inaccurate voltage divider ratios. Some use the method of dividing voltage by connecting capacitors in series after passing through a medium voltage transformer. Therefore, the cumulative error is relatively large.
2. Low insulation: Aluminum foil electrode capacitors do not have self-healing characteristics in terms of voltage resistance, and currently there are still 3 ‰~5 ‰ breakdown phenomena occurring during operation.
3. Low voltage division ratio: For medium voltage above 10KV, even after passing through a medium voltage transformer, the medium voltage still exceeds 50V, which cannot meet the input requirements of EVT and OVT.
4. Oil immersed insulation type: easy to burn, not conducive to safety control, and complex to maintain.
5. SF6 insulation type: SF6 has a significant greenhouse effect, which is 23900 times that of CO2 (i.e. for every 1g of SF6 leaked, it is equivalent to emitting about 24kg of CO2 into the air). Its atmospheric lifespan is up to 3200 years (30 times that of CO2), and ionization at high voltage can produce toxic and corrosive decomposition products.
6. Magnetic type: CVT uses medium voltage transformers, so there are both electromagnetic compatibility issues and ferromagnetic resonance risks.
New features of nitrogen based and environmentally friendly capacitive voltage dividers ("three highs", "three nos")
1. High accuracy: accuracy level of 0.1/0.2. This is mainly due to the following characteristics of self-developed and produced high-voltage capacitors and medium voltage capacitors:
(1) The temperature coefficient of the capacitor is small.
(2) The temperature stability of the capacitor is good, and the capacitance drift is almost zero.
(3) The parameters of high-voltage capacitors and medium voltage capacitors are matched, with good consistency in temperature characteristics and a small range of error in voltage division ratio.
(4) The working temperature rise of capacitors is small, usually only about 1 ℃.
(5) Medium voltage capacitors have a large capacitance ratio and can achieve a 5V medium voltage output by series voltage division (traditional products usually require 2 or more voltage divisions to achieve). Therefore, the cumulative error is very small.
2. High insulation: There will be no breakdown phenomenon during operation. This is mainly due to:
(1) The self-developed and produced high-voltage capacitors have self-healing characteristics (traditional aluminum foil electrode capacitors do not have self-healing characteristics), and are dry cylindrical (traditional aluminum foil capacitors need to be pressed into rectangles), with relatively uniform electric field distribution inside and on the end face.
(2) This dry-type capacitor has no partial discharge at twice the operating voltage.
(3) The installation and arrangement of capacitors inside the voltage divider are scientific and reasonable, and the insulation strength between adjacent capacitors is very high.
3. High voltage division ratio: It can directly obtain medium voltage of 5 ± 1V, which is convenient for EVT, OVT, and smart grid control interfaces.
4. Oil free: Fill with high-purity nitrogen as a filler to prevent oxidation and low-temperature condensation. It has achieved oil-free operation, eliminated fires, and is easy to maintain.
5. SF6 free: completely eliminates the hidden dangers of greenhouse effect, which is very beneficial for environmental protection.
6. Non magnetic: Without the need for a medium voltage transformer, there are no issues with ferromagnetic resonance or electromagnetic compatibility.
Application conditions
1. Installation and operation location: outdoor or indoor 2. Altitude: 2000m
3. Environmental humidity: -40 ℃~+85 ℃ 4. Wind speed: ≤ 42m/s
5. Leakage distance (mm/KV): ≥ 31.6, earthquake intensity: not exceeding 8 degrees
7. Ice thickness: ≤ 10mm 8. System rated frequency: 50 (60) Hz
9. System grounding conditions: effective grounding of neutral point or ineffective grounding of neutral point.

Model description of CVDN series nitrogen based environmentally friendly capacitive voltage divider


Main technical performance
1. Execution standard: GB/T19749-2005
2. The typical technical and structural parameters of the product are shown in Table 1
3. Capacitance deviation: -5% to+10%
4. Tangent value of loss angle: tg8 ≤ 10 × 10-4 (20 ℃)
5. Partial discharge capacity



6. Voltage division ratio accuracy level: 0.1/0.2
7. Medium voltage output: 5 ± 1V
8. The product can operate for a long time at 1.2 times the rated voltage or below. The neutral point effective grounding system can operate for 60 seconds at 1.5 times the rated voltage, and the neutral point non effective grounding system can operate for 8 hours at 1.9 times the rated voltage.

Table 1 List of Main Technical Performance and Structural Parameters of Nitrogen type and Environmentally friendly Capacitive Voltage Dividers