问题 问答题 简答题

方向继电器电路要满足哪些技术要求?

答案

参考答案:

(1)用先按下的按钮即始端按钮的按钮继电器前接点接通对应的方向继电器电路,使相应的方向继电器吸起,来记录、确定运行方向和进路性质。

(2)四个方向继电器同时只准许一个吸起,即同一时间内只能选一条进路(同方向同性质的进路除外)。

(3)方向继电器在选路的全过程中都要参与工作,在进路未全部选出以前,应使方向继电器保持在吸起状态。

(4)进路全部选出后,方向继电器能及时自动复原;因故不能正常选出时,方向继电器应能手动复原。

(5)办理取消和人工解锁进路及重复开放信号时,也要按压进路始端按钮,因为这时不是选路,所以不应使方向继电器动作。

阅读理解

In most parts of the world, many students help their school make less pollution. They join in “environment clubs”. In an environment club, people work together to make our environment clean.

Here are things students often do:

Turn off the water! Do you know that some toilets can waste twenty to

forty tons of water an hour? In a year, that would fill a small water! In environment clubs, students mend those broken toilets.

No-car day. On a no-car day, nobody comes to school in a car-not the students and not the teachers. Cars give pollution to our air, so remember: walk, jump, bike or run.

Use your legs! It’s lots of fun!

No-garbage(垃圾) lunches. How much do you throw away after lunch?

Environment clubs ask students to bring their lunches in bags that can be used

again. Every week they will choose the classes that make the least garbage

and report them to the whole school.

We love our environment! Let’s work together to make it clean!

小题1: After mending the broken toilets, they save      .

A.a small river

B.a lot of water

C.a toilet

D.a year小题2:On a no-car day,      will take a car to school.

A.only students

B.only teachers

C.both students and teachers

D.neither students nor teachers小题3:Environment clubs ask students        .

A.to run to school every day

B.to play sports every day

C.not to throw away lunch bags

D.not to forget to take cars小题4:From the passage we know that students usually have lunch       .

A.at school

B.in clubs

C.at home

D.in shops小题5:The write wrote the passage to tell students to       .

A.join in clubs

B.help teachers

C.make less pollution

D.clean schools

多项选择题