问题 问答题 简答题

选择高压电气设备应满足哪些基本条件?

答案

参考答案:

应满足以下基本条件。

(1)绝缘安全可靠:既要长期承受工频最高工作电压,又要能承受内部过电压和外部过电压。

(2)在额定电流下长期工作,其温升应合乎标准,且有一定的短时过载能力。

(3)能承受短路电流的热效应和电动力而不致损坏。

(4)开关电器设备,应能安全可靠地关、合规定电流。

(5)户外设备应能承受自然条件的作用而不致受损。

材料题
阅读理解

Man’s best friend could be one of the environment’s worst enemies, according to a new study that says that your pet dog’s carbon pawprint(碳足迹) is more than double that of a sports car.

Yet this point of view, made by New Zealanders Robert and Brenda Vale, has angered pet owners who feel they are being picked out as troublemakers.

The Vales, researchers in sustainable(可持续的) living, looked at popular brands of pet food and calculated that a medium-sized dog eats about 164 kilos of meat and 95 kilos of grain a year.

Combining that with the energy needed to produce that food, it means a medium-sized dog has an annual footprint of 0.84 hectares(公顷), about twice the 0.41 hectares required by a sports car driving 10,000 kilometers a year, including energy to build the car.

“Owning a dog really is quite an extravagance(奢侈), mainly because of the carbon footprint of mean. Other animals aren’t better for the environment,” the Vales say.

Cats have an eco-footprint of about 0.15 hectares a year, while two hamsters(仓鼠) are the same as a television and even the goldfish burns energy equal to two cellphones.

However, Reha Huttin, president of France’s 30 Million Friends animal rights foundation says pets are too important to human life to be got rid of.

“Everyone should work out their own environmental effect,” Huttin argude. “I should be allowed to say that I walk instead of using my car and that I don’t eat meat, so why souldn’t I be allowed to have a little cat to reduce my loneliness?”

The Vales give some solutions to reduce pets’ environmental effect, including reducing pets’ meat intake. But they said that, as with buying a car ,humans should take the environmental effect of their future compainon into account.

71.The best title of the article is "______".

A.Work out our carbon emissions        B.Reduce our pets’ meat intake

C.Be careful of keeping our pets         D.Mind our pets’ carbon footprint

72.Reha Huttin’s remark really means that ______.

A.pets should not be kept as a result of consuming much food

B pets are doing no harm to the environment at all

C.people can keep pets by reducing their environmental effect

D.he prefers walking to driving to reduce his loneliness

73.We know from the article that ______.

A.a medium-sized dog eats around 95 kilos of grain and meat a year

B.a medium-sized dog has an annual footprint 5.6 times that of a cat

C.two hamsters burn the same energy as two televisions

D.a sports car running 10,000 kilometers requires 0.41 hectares of footprint

74.Which of the following is NOT true according to the article?

A.The Vales insist that pets should be got rid of.

B.Some pet owners are against the Vales’ point of view.

C.Keeping pets does have a bad effect on the environment.

D.Pets’ carbon footprint should not be neglected.

75.Which of the following can help reduce pets’ environmental effect based on the text?

A.Feeding pets on less meat.

B.Working out eco-footprints of pets.

C.Keeping the goldfish instead of dogs.

D.Getting rid of pets from human life.