问题 问答题 简答题

发电机运行电压过低会产生哪些后果?

答案

参考答案:

(1)当发电机电压低于额定电压90%时,定子铁芯将处于不饱和状态运行,使电压不稳定,若励磁稍变,电压就有较大变化。甚至引起失步破坏系统稳定; 

(2)电压过低,将使厂用电动机运行工况恶化; 

(3)若要保持发电机容量不变,当电压过低时,就必须增加定子电流,则定子线圈温度增高,否则降低发电机容量运行。

阅读理解

The national schools’ first aid competition is an interesting way for young people to practice their first aid skills in a safe environment.

A school may have three teams. The deadline for this competition has now been continued to April 21, 2012. All teams will compete at an elimination (淘汰) round, with the winners going forward to the National Final for the chance to become the winner.

A team has three formal members, and a reserve is also needed. All team members, together with the reserve, will take part. There are two age sections:

Junior: 7 to11

Senior: 12 to 16

This competition is based on the Young First Aid Course from St. John Ambulance Training Officer. Support will be given to make sure everyone has equal chances to win.

The winners of this competition will be invited to take part in the Young Grand Prior Competition. This competition improves the practical first aid skills of young people and tests their knowledge and skills with a series of realistic accidents and injuries. Youth teams are aged between 12 and 16 years old and should have three members. Young adults are aged between 17 and 21 and should have two members. All teams may bring a reserve. The Young Grand Prior Competition will be held at the Spa Complex, Scarborough, on November 28, 2012.

Those who want to take part in the national schools’ first aid competition will have to complete our application form.

小题1: If you are fifteen and want to take part in the competition, you will _________.

A.belong to the junior sections of the first aid competition

B.complete our application form by the end of April, 2012

C.study the course of St. John Ambulance Training Officer

D.teach yourself a lot of knowledge and skills of first aid小题2: How many students will stand for a school?

A.Sixteen

B.Twelve

C.Four

D.Three小题3:Form the passage we can learn that the Young Grand Prior Competition will __________.

A.have a test with realistic accidents and injuries

B.not allow the adult competitors to take part in

C.be the highest level competition in the country

D.be held on April 21, 2012小题4:The passage is written mainly for __________.  

A.those who want to practice their first aid skills

B.the young school students in the country

C.the middle school teachers in the country

D.the young people throughout the country