问题 问答题 简答题

变压器比率制动的差动继电器制动线圈接法的原则是什么?

答案

参考答案:

通常要求该保护装置在外部故障时具有可靠的选择性,流入保护的制动电流为最大;而在内部故障时,又有较高的灵敏度。因此,差动继电器制动线圈的接法原则一般为:

(1)变压器有电源侧互感器如接入制动线圈,则必须单独接入,不允许经多侧电流互感器并联后接入制动线圈。

(2)变压器无电源侧电流互感器必须接入制动线圈。

选择题
阅读理解

阅读理解。

     Living in a green area can make you live longer, according to the research published today.

The research also shows that the difference in life expectancy (平均寿命) between rich and

poor becomes smaller among those who live in an environment with parks and trees.

     Richard Mitchell, from Glasgow University, and his colleagues, found that the gap between

the number of deaths of people on high incomes and the number of deaths of those on low

incomes in green areas was half that compared with figures relating to builtup areas.

     Green spaces, classified by the researchers as "open, undeveloped land with natural

vegetation", encouraged people to walk and be more active. Exercise in these settings could

have greater benefits than exercise elsewhere, the researchers said.

     The benefits potentially go beyond exercise. Studies have shown that being around green

spaces can reduce blood pressure and stress levels, and possibly help patients recover faster.

     A number of researchers have looked at the effects of greenery on our wellbeing. But few

studies had looked at whether living in green areas reduced health inequalities, the Glasgow

team said.

     Using information from a landuse database of 2001, the researchers divided the preretirement

population of England into four groups according to income level, and five groups according to

access to green space. They then looked at death rate for 2001-2005.

     They found that the inequality in death rate from all causes relating to lack of money was less

in those populations in the greenest areas compared with the figures for people living in more

builtup places. They found an even stronger relationship when it came to deaths from certain

diseases such as heart conditions and stroke (中风). There was no difference, however, in

deaths from lung cancer.

     The researchers said that changing the physical environment was an easier way to fight

against poor health than using media campaigns or giving out information on health. "The result

of the study is clear, environments that promote good health might be very important in the fight

to reduce health inequalities."

1. The underlined word "that" in Paragraph 2 refers to ________.

A. the gap                          

B. the number of deaths

C. the income                      

D. the living area

2. What was the special point of the Glasgow team's research? 

A. They offered a scientific definition of "green spaces".

B. They encouraged people to exercise in green areas.

C. They studied the effects of greenery on people's diseases.

D. They focused on the influence of greenery on health inequalities.

3. What advice would the researchers probably give according to the last paragraph? 

A. More health information should be given to the public.

B. People should take more exercise every day.

C. More trees and grasses should be planted in cities.

D. People should fight against health inequality.

4. What is the main idea of the passage?

A. People should live in green areas.

B. Green spaces promote good health.

C. Income influences health less than environment.

D. Exercise in green areas benefits people a lot.