Oxford English for Electrical and Mechanical Engineering //E. H. Glendinning, ...
in Use: A self-reference and practice book for intermediate students of English.
FEA // 4th year of study // 7th term
Lesson 3 EQUIVALENT 1. 2. 3. 4. 5.
CIRCUITS
Business course: “At the Exhibition” (dramatizing dialogue). Reading. Text “Equivalent circuits”. Exercises: gapped sentences, giving definitions. Grammar: Passive Voice (revision). Practice in grammar: sentence transformations, gap-fill exercises. Language focus: Cause and Effect. Sentence transformations.
References 1. . ., . . . – 5., . – .: « », 2001. – 352 . 2. ( V ) // : . . , . . , . . .– .: , 2001. – 64 . 3. Oxford English for Electrical and Mechanical Engineering //E. H. Glendinning, N. Glendenning. – Oxford University Press, 1995. – 190 p. 4. Murphy Raymond. Essential Grammar in Use: A self-reference and practice book for intermediate students of English. – Cambridge University Press, 1994. – 350 p. 5. Grammar way 4 // V. Evans. – Express Publishing, 1999
1. Dramatizing Dialogue “At the Exhibition”
2. Reading EQUIVALENT CIRCUITS An actual transformer may be represented, for purposes of explanation, as consisting of an ideally perfect transformer, having no losses or magnetizing current, together with various additions to allow for these effects.
Fig. 13. Equivalent Circuits of a Transformer
Fig. 13. represents such an ideal transformer having a resistance, R1, and a reactance X1, in series with its primary winding, and a resistance, R2, and a reactance, X2, in series with its secondary winding. The no-load current has both an active and a reactive component The latter is the magnetizing current of the iron core, Im, and is represented in the diagram by the current flowing through an additional reactance, while the active component, Ic, supplying the iron losses in the core, is represented by the current flowing through an additional resistance. The vector resultant of Im and Ic is I0, which is the total no-load current of the transformer. The secondary current is I2, and the component of the primary current that neutralizes I2 is I'1 The total primary current, I1, is the vector sum of this component, I'1, and the no-load current, I2. The turns in the primary and secondary windings are T1 and T2 respectively, and are so related that
The flux I is the useful flux linking both primary and secondary windings. The induced secondary e.m.f. is E2, this being slightly greater than the secondary terminal voltage, V2, since the secondary resistance, R2, and the secondary reactance, X2, cause voltage drops of I2R2 and I2X2 in phase and in quadrature with the current, I2, respectively. The back induced e.m.f., 1, is related to E2 by the formula
The primary applied voltage, V1, is again slightly larger than E1, on account of the voltage drops caused by the primary resistance, R1, and the primary reactance, X1. These again bring about voltage drops of I1R1 and I1X1 in phase and in quadrature with the primary current, I1, as before. EXERCISES 1. What do the following letters stand for?
1. R1 ___________________ 2. R2 ___________________ 3. X1 ___________________ 4. X2 ___________________ 5. Im ____________________ 6. Ic ____________________ 7. I0 ____________________ 8. I1 ____________________ 9. I'1 ____________________ 10.I2 ____________________ 11.I`2 ____________________ 12.T1____________________ 13.T2____________________ 14.E2____________________ 15.E1____________________ 16.V1____________________ 2. Read the text, close the book and complete the following sentences according to the text: 1. An actual transformer may be represented as consisting of an ideally perfect transformer, having no _____________ or ____________, together with various additions to allow for these effects. 2. The no-load current has both an ___________ and ___________ component. 3. The vector resultant of Im, and Ic is I0, which is the total _________ __________ of the transformer. 4. The _________ in the primary and secondary __________ are T1 and T2 respectively. 5. The primary applied voltage is again slightly _____________ than the back induced e.m.f.
3. Grammar PASSIVE VOICE
Changing from Active into Passive
Only transitive verbs (verbs followed by an object) can be changed into the passive. e. g. active: Grandma knitted my jumper. (transitive verb) Passive: My jumper was knitted by grandma. But: They travelled to London last year. (intransitive verb) Some transitive verbs such as have, fit, suit, resemble, etc. cannot be changed into the passive. e.g. I have a shower every morning. (Not: A shower is had by me…)
4. Practice in Grammar. Passive Voice I. Rewrite the sentences in the passive. Omit the agent where possible 0 Do they sell clothes in this shop? --- Are clothes sold in this shop? 1 Terry offered her a lift to work…………………………………………….. 2 They awarded him a prize for this competition entry……………………… 3 Will they play the tennis match on an indoor court? ...................................... 4 Will you have completed the task by Friday evening? ................................. 5 Who made all these cakes? ............................................................................ 6 Who teaches theoretical grounds of electrical engineering at this faculty? ....................................................................................................................... II. Rewrite each sentence, beginning as shown, so that the meaning stays the same.
a) A friend lent George the motorbike he rode in the race. The motorbike George rode in the race …………………………… . b) At the time my aunt was looking after the children for us. At the time our children ……………………………………… . c) The police have issued a description of the wanted man. A description ………………………………………………… . d) It was a mistake to enter Brian for the exam. Brain should not ……………………………………………… . e) They said they would rather Diana didn’t listen to music at work. Diana …………………………………………………………… . f) Johnson first became a member of Parliament in 1983. Johnson was first ………………………………………………… . g) My legal advisers have told me not to say any more at this time. I have ……………………………………………………………… . h) Nobody had invited Jean to the party, which annoyed her. As she ……………………………………………………………… . i) Tony has another six months to finish his thesis. Tony has been ……………………………………………………… . j) There is no definite decision yet about the venue of the next Olympic Games. Nothing ………………………………………………………………… . III. Put each verb in brackets into the passive in an appropriate tense. a) Nothing …………… (see) of Pauline since her car …………… (find) abandoned near Newbury last week. b) As our new furniture …………… (deliver) on Monday morning I’ll have to stay at home to check that it ……………… (not damage) during transit. c) The new Alhambra hatchback, which in this country …………… (sell) under the name ‘Challenger’, ………… (fit) with electric windows as standard. d) For the past few days I …………… (work) in Jack’s office, as my own office ……………… (redecorate). e) The last time I went sailing with friends the boat …………… (sink) in a gale. Luckily I ……………… (not invite) again since then!
f) It ……………… (announce) that the proposed new office block ………………… (now not build) because of the current economic situation. g) A major new deposit of oil …………… (discover) in the North Sea. It ………………… (think) to be nearly twice the size of the largest existing field. h) Pictures of the surface of the planet Venus …………… (receive) yesterday from the space probe ‘Explorer’ which ……………… (launch) last year. i) A large sum ……………… (raise) for the Fund by a recent charity concert but the target of £250 000 ………………… (still not reach). j) No decision ……………… (make) about any future appointment until all suitable candidates …………………… (interview). IV.
Rewrite the following passage in the passive.
Last week, the Prime Minister visited Dawston. The Mayor of the town greeted him when he arrived and gave him a tour. He introduced the Prime Minister to some important businessmen and took him to lunch in a local restaurant. In the afternoon, the Mayor held a meeting and the Prime Minister addressed the citizens of Dawston. He told them that he had enjoyed his visit very much.
5. LANGUAGE STUDY Cause and Effect Task1 Study this text on the four-stroke cycle. Then label each stroke correctly in Fig.2. In the four-stroke cycle, the piston descends on the intake stroke, during which the inlet valve is open. The piston ascends on the compression stroke with both valves closed and ignition takes place at the top of the stroke. The power or expansion stroke follows. The gas generated by the burning fuel expands rapidly, driving the piston down, both valves remaining closed. The cycle is completed by the exhaust stroke, as the piston ascends once more, forcing the products of combustion out through the exhaust valve. The cycle then repeats itself.
Study these pair of actions. What is the link between them? 1 The gas expands. 2 This drives the piston down. 3 The piston ascends. 4 This forces the products of combustion out. There are two links between the actions: They happen at the same time. We can show this using AS. 1+2 As the gas expands, it drives the piston down. 3+4 As the piston ascends, it forces the products of combustion out. One is a cause and the other an effect. 1 The gas expands. (cause) 2 This drives the piston down. (effect) 3 The piston ascends. (cause) 4 This forces the products of combustion out. (effect) We can show both the time link and the cause and effect link like this: 1+2 The gas expands, driving the piston down. 3+4 The piston ascends, forcing the products of combustion out.
Task 2 Link these actions in the same way.
We can link the cause and effect when both are nouns or noun phrases.
Task 3. Study these lists, A and B. Items in list A are causes of those in list B but the items are mixed up. Link the related items and write the sentences to show the link. e.g. Loss of strength results from reduction in cross-section.
