In electrical systems for the generation, distribution and use of electrical energy considerable control equipment is ne¬cessary. It can be divided into two classes: a) equipment used at the generating and distributing end; b) equipment used at the receiving end of the system. Safety switches are used at the point where the power en¬ters a building. They are of the knife type and are usually en¬closed in metallic boxes.
A magnetic contactor is used to make and break the circuit at the points where considerable power is used.
An automatic starter is a device which is used to keep the current from being excessive while the motor is obtaining full speed. It is a kind of a resistance inserted in series with the direct current armature. As the motor obtains speed it gradu¬ally removes.
Answer the questions:
1. Where is considerable control equipment necessary?
2. What classes can it be divided in?
3. Where are the safety switches used?
3. I wondered if it had been possible to get seats for the new performance.
4. I wondered if Diana had ever been to the Bolshoi box office.
5. I wondered if the dramatist was writing a new comedy then.
6. I wondered if everyone had noticed the elegance of the scenery on the stage.
7. I wondered why there was so much cruelty in the film.
8. I wondered how long the intervals between the acts were.
9. I wondered if Maria had received my e-mail the day before.
10. I wondered to what theatre they had gone in the first place.
11. I wondered how we could reply to that greeting.
12. I wondered how many people the theatre could hold.
I listened to hte radio untill twelve o'clock last night
He always wanted to learn English
Ann and I talked over the telephone yesterday
They lived France for many years
The meeting lasted about two hours
I waited almost two hours for Helen yesterday
She studyed in owr class last semester
We watched television until eleven o'clock last night
Mr. and Mrs. Simpson invited all their friends and neighbours to a party last night
In the morning my parents worked outside
I met a friend on my way to class
Someone stole my bike and I had to call the police
I played football on my weekend
In winter I skated