问题 问答题 简答题

什么是可变损失?

答案

参考答案:可变损失是指随负荷电流的变动而变化的损失。可变损失与电流的平方成正比,电流越大,损失越大。电网中电力设备的可变损失主要包括:

(1)发电厂、变电所的主变压器及配电变压器的短路损耗(铜损)。

(2)调相机、调压器、互感器、电抗器、消弧线圈等电力设备的铜损。

(3)电流流过输电线路、配电线路时,在其线路电阻中产生的功率损耗。

(4)绝缘子表面泄漏的损耗。

(5)电能表电流线圈的功率损耗。

(6)进户线路的铜损。

单项选择题
阅读理解

阅读理解。

     You know Australia is a big country, but you may not know how easy it is to get around. The

untouched beaches that go for miles and deserts that touch the horizon are just there, waiting to be

reached and explored. Following are the different ways you can explore our vast country.

Getting around Australia

     Air

     Flying is the best way to cover large distances in a short time. You can spend more time on the

Australia's can't-miss landscapes and relaxing lifestyle. Moreover, competition among airlines makes

great flying fees available for you.

     Drive

     Australia has a vast network of well - maintained roads and some of the most beautiful touring

routes in the world. You have no difficulty finding car rental companies at major airports, central city

locations, suburbs and attractions.

     Bus

     Bus travel in Australia is comfortable, easy and economical. Buses generally have air conditioning,

reading lights, adjustable seats and videos. Services are frequent, affordable and efficient.

     Rail

      Train travel is the cheapest and gives you an insight into Australia's size and variety, all from the

comfort of your carriage. Scheduled services are a great way to get quickly between our cities and

regional centers.

     Ferry (轮渡)

     The Spirit of Tasmania runs a passenger and vehicle ferry service between Melbourne and Tasmania

nightly. Extra services are running during summer rush hours. Sea - link ferries connect South Australia

and Kangaroo Island several times a day. Ferries connect suburbs in our capital cities

     Walk

     With easy - on - the - feel pedestrian streets, walking is a great way to get around our cities.

Besides all of above, you can also experience some of the longest tracks and trails in the world in central

Australia - impressive journeys of a thousand kilometers or more that can take several weeks to complete.

1. The underlined word "untouched" (in the 1st paragraph) means______.

A. ordinary        

B. dangerous        

C. natural        

D. boring

2. Which of the following is TRUE about traveling in Australia? ______.

A. More travelers make the flying fees among airlines higher than before

B. You can easily rent a car to explore its most beautiful touring routes

C. Taking a bus tour is the cheapest way

D. Train travel is uncomfortable

3. Ferry service between Melbourne and Tasmania usually runs ______.

A. only at night hours                    

B. only during rush hours

C. several times a day                    

D. between different cities

4. From the passage, we know that ______.

A. pedestrian walking is a great way to travel between cities

B. it takes much time to travel in Central Australia

C. you can also experience the impressive journeys of a thousand meters in central Australia

D. you have to walk over a thousand kilometers in Australia.