CN102136311A

CN102136311A - Mixed gas insulating medium

Info

Publication number: CN102136311A
Application number: CN 201010540135
Authority: CN
Inventors: 张国强; 邢卫军; 李康; 牛文豪; 王新
Original assignee: Institute of Electrical Engineering of CAS
Current assignee: Institute of Electrical Engineering of CAS
Priority date: 2010-11-10
Filing date: 2010-11-10
Publication date: 2011-07-27

Abstract

The invention discloses a mixed gas insulating medium comprising the following components in percent by volume: 15-20 % of octafluorocyclobutane and 80-85% of nitrogen. The mixed gas insulating medium disclosed by the invention can serve as a new generation of gas insulating medium by replacing sulfur hexafluoride and can be widely applied to high-voltage power equipment, such as gas insulated transformers, gas insulated combined electrical appliances, gas insulated power transmission pipelines and the like.

Description

A kind of mist dielectric

Technical field

The present invention relates to the mist dielectric that a kind of alternative sulphur hexafluoride is used for high voltage electric power equip ment.

Background technology

SF ₆Gas has good insulation performance ability, arc extinguishing ability, chemical stability and avirulence, thereby is widely used in the air insulating device, as gas-insulated transformer, gas insulation breaker, gas-insulated transmission of electricity pipeline etc.But, pure SF ₆Gas is very responsive to the electric field inhomogeneities, apparatus processing is required high; And SF ₆The discharge analyte of gas is as SO ₂F ₂, SOF ₂, SF ₄, SF ₂, H ₂S, SOF ₄Deng, be extremely toxic substance, threaten very big to the personnel health; In addition, SF ₆The greenhouse effect of gas are very big, and its global warmization latent energy value (GWP) approximately is CO ₂23900 times of gas, and in atmosphere about 3200 of life-span, so the climate change pact contracting party of the United Nations is in the Kyoto Protocol of signing in 1997, with SF ₆Gas is classified one of greenhouse gas of six kinds of restricted uses as.Therefore the scientific research personnel has carried out a large amount of research, wishes to search out to substitute SF ₆Gas is used for the new medium of electric equipment.

At present, replace SF with pure gas ₆Gas is very difficult.So people attempt using mist to replace pure SF ₆Gas.The existing at present SF that uses ₆/ N ₂Mist or SF ₆/ CO ₂Mist instead of pure SF ₆The report of gas as when the track remodelling of Geneva, Switzerland airport, uses to have charged into 20%SF ₆/ 80%N ₂The gas-insulated transmission of electricity pipeline of mist replaces original overhead wire.Use contains SF ₆Mist following advantage is arranged: reduce the electrode surface flaw sensitivity, reduce the gas liquefaction temperature, reduce cost, therefore have application promise in clinical practice, particularly SF ₆Content is at 20%～40% SF ₆/ N ₂Mist.

But, use to contain SF ₆Mist can not fundamentally solve SF ₆The extremely toxic substance that contains in the greenhouse effect of gas and the catabolite thereof is to the threat of the person.Therefore, be necessary that searching does not contain SF ₆Mist be used for high voltage electric power equip ment.

Disclose " a kind of gas-insulated transformer " in 02103455.9, this patent use global warming coefficient is equal to or less than 1 inert gas as dielectric, although environment protecting improves greatly, the inert gas insulating properties are far below SF ₆, so that the power equipment volume increases, producing cost increases.

A kind of " environmental-protective gas-insulating combined electric appliance " disclosed in 200610084702.8, this patent uses dry low-pressure air as dielectric, reduced harm to environment, but because the insulating capacity of air is relatively poor, so this patent mainly is applicable to the power equipment that 12kV is following.

Disclose a kind of " gas insulated electric apparatus " in 200710001562.8, this patent uses volumetric ratio to surpass 40% CF ₃I and other non-SF ₆Gas mixes and forms dielectric, reduces the impact to environment, but CF ₃The I less stable is easily decomposed, and therefore needs to increase adsorbent and increases the maintenance number of times, so that operating cost increases.

Summary of the invention

The object of the present invention is to provide that a kind of environment protecting is good, good insulation preformance, alternative SF ₆Gas is used for the mist dielectric of high voltage electric power equip ment.

The component of mist dielectric provided by the present invention is octafluorocyclobutane 15%～20% (percent by volume) and nitrogen 80%～85% (percent by volume).

In the mixed gas insulating medium provided by the present invention, component octafluorocyclobutane, chemical molecular formula are C ₄F ₈, molecular weight 200.0, boiling point-8 ℃, nontoxic, ozone free harm, warmization latent energy value is 8900, is about SF ₆37% of gas, partial discharge inception voltage is about SF under the same pressure ₆1.2～1.4 times.The catabolite of this component under 600 ℃ of overheated conditions mainly contains C ₂F ₄, C ₃F ₆, 1,3-C ₄F ₆, c-C ₄F ₆, 2-C ₄F ₈, the main catabolite under arcing has C ₂F ₄, C ₃F ₆, 1,3-C ₄F ₆, c-C ₄F ₆, 2-C ₄F ₈, C ₂F ₆, C ₃F ₈, these catabolites all belong to nontoxic or low toxicity material.

In the mist dielectric provided by the present invention, component nitrogen is buffer gas, mainly act as the boiling point that reduces mist.The boiling point of mist of the present invention can satisfy the instructions for use in winter of most areas below-20 ℃.

Mist dielectric provided by the present invention has well satisfied the requirement of aspects such as environmental protection, personal safety, the gas-insulated medium SF that mainly uses with present high voltage electric power equip ment ₆Compare, following advantage arranged:

1, good environmental protection.The whole warmization latent energy value of the mist that this invention provided is lower than 2000, less than SF ₆10% of warmization of gas latent energy value can well improve SF ₆The greenhouse effect that gas causes environment.

2, hazard to person is low.The main catabolite of the mist that this invention provided under the power equipment running status is nontoxic or low toxicity material, unlike SF ₆The catabolite majority of gas belongs to extremely toxic substance, as deals with improperly and will threaten to personal safety.

Description of drawings

Fig. 1 is pure C ₄F ₈Gas and SF ₆Starting voltage is put with the air pressure change curve in gas office;

Fig. 2 is C ₄F ₈/ N ₂The condensing temperature T of mist _MbRelation curve with mixing ratio k;

When Fig. 3 is the 20mm electrode distance, C ₄F ₈/ N ₂Starting voltage is put with the air pressure change curve in mist office;

When Fig. 4 is the 30mm electrode distance, C ₄F ₈/ N ₂Starting voltage is put with the air pressure change curve in mist office.

Embodiment

The content that the following describes the main component that constitutes mist of the present invention limits reason.

At first, component octafluorocyclobutane, chemical molecular formula are C ₄F ₈, molecular weight 200.0, boiling point-8 ℃, nontoxic, ozone free harm, warmization latent energy value is 8900, is about SF ₆37% of gas, partial discharge inception voltage is about SF under the same pressure ₆1.2～1.4 times, shown in Fig. 1 experimental result.C ₄F ₈Catabolite under 600 ℃ of overheated conditions mainly contains C ₂F ₄, C ₃F ₆, 1,3-C ₄F ₆, c-C ₄F ₆, 2-C ₄F ₈, the main catabolite under arcing has C ₂F ₄, C ₃F ₆, 1,3-C ₄F ₆, c-C ₄F ₆, 2-C ₄F ₈, C ₂F ₆, C ₃F ₈, these catabolites all belong to nontoxic or low toxicity material.Therefore, C ₄F ₈Be comparatively ideal environmental protection, low harm dielectric, shortcoming is exactly that its condensing temperature is higher, and is inapplicable at cold district and winter.

Secondly, in order to improve C ₄F ₈The condensing temperature of gas adds N therein ₂As buffer gas.The general requirement of power equipment can normally be moved at-20 ℃, and the gas-insulated medium in the power equipment generally exists with the state of 0.4～0.5MPa simultaneously, therefore requires mist under the state of 0.4～0.5MPa, and its condensing temperature is lower than-20 ℃.Fig. 2 has provided C ₄F ₈/ N ₂Mist is under 0.4MPa and 0.5MPa state, and the mist condensing temperature is with C ₄F ₈The change curve of gas content.As seen from Figure 2, under the 0.4MPa state, C in mist ₄F ₈When the content of gas surpasses 20%, the condensing temperature of mist will be higher than-20 ℃; 0.5MPa under the state, C in mist ₄F ₈When the content of gas surpasses 15%, the condensing temperature of mist will be higher than-20 ℃.Therefore, from the angle of mist condensing temperature, C in the mist ₄F ₈Content should not surpass 20%.

The 3rd, as dielectric, the insulating properties of mist also need to reach certain requirement, otherwise will cause the power equipment size big, material consumption height, production cost height.Fig. 4 and Fig. 5 have provided respectively C ₄F ₈Gas content is below 20%, and electrode distance is respectively 20mm and 30mm, gas atmosphere when 0.1～0.4MPa, C ₄F ₈/ N ₂The result of partial discharge inception voltage test of mist.Can be seen by result among the figure, gas atmosphere when 0.4MPa, C ₄F ₈Content is put starting voltage in 15%～20% mist office and be 22kV under the 20mm electrode distance, is 26kV under the 30mm electrode distance, approximately is SF under the same terms ₆70% of starting voltage is put in gas office, with SF ₆Content is at 20% SF ₆/ N ₂It is consistent that performance is put in mist office.Therefore, use C ₄F ₈Gas content only need increase the insulation distance of power equipment slightly at 15%～20% the mist dielectric as power equipment, can satisfy insulating requirements, and production cost is increased by a fairly big margin.If C in the mist ₄F ₈Content is lower than 15%, and the decreasing insulating of mist is more with making, thereby makes power equipment need bigger insulation distance, thereby consumes more material.Therefore, require C in the mist ₄F ₈Content is 15%～20%.

The present invention will be further described below in conjunction with accompanying drawing, embodiment and comparative example, but the invention is not restricted to these examples.

Embodiment 1:C ₄F ₈Content is 20% (percent by volume) and N ₂Content is the mist that 80% (percent by volume) consists of;

Embodiment 2:C ₄F ₈Content is 19% (percent by volume) and N ₂Content is the mist that 81% (percent by volume) consists of;

Embodiment 3:C ₄F ₈Content is 18% (percent by volume) and N ₂Content is the mist that 82% (percent by volume) consists of;

Embodiment 4:C ₄F ₈Content is 17% (percent by volume) and N ₂Content is the mist that 83% (percent by volume) consists of;

Embodiment 5:C ₄F ₈Content is 16% (percent by volume) and N ₂Content is the mist that 84% (percent by volume) consists of;

Embodiment 6:C ₄F ₈Content is 15% (percent by volume) and N ₂Content is the mist that 85% (percent by volume) consists of;

Comparative Examples: SF ₆Content is 20% (percent by volume) and N ₂Content is the mist that 80% (percent by volume) constitutes;

The composition and the relevant nature of embodiment 1,2 and Comparative Examples see the following form:

Can be seen that by comparing result embodiment office puts starting voltage and is not less than Comparative Examples under the similarity condition, promptly insulation property are better than Comparative Examples, and warmization coefficient is respectively 37.5%, 35.2%, 33.3% of Comparative Examples, 31.4%, 29.5% and 27.8%, promptly greenhouse effect are weaker than Comparative Examples.

Claims

1. mist dielectric, it is characterized by: the percent by volume of described mist dielectric component is: 15%～20% octafluorocyclobutane, 80%～85% nitrogen.