Instrument potential transformer 4 страница
TASK 3. Answer the following questions and retell the text.
1. What devices are called condensers? 2. What does the simplest condenser consist of? 3. What does the capacitance of a condenser depend on? 4. In what way are the plates of a condenser connected together if a capacitor consists more than of two plates? 5. What are the most common types of dielectrics? 6. What types of condensers are in use nowadays? 7. What quantities can be varied in a condenser? 8. What is the basic unit of capacitance?
TASK 4. Translate the following words, pay attention to the prefix: reproduce, repay, recreate, remark, reform, retell, rebuild, reconstruct, readjust.
TASK 5. Match the words.
1. device а) ослаблять
2. size b) слюда
3. charge c) поток
4. potential difference d) заряд
5. exist e) электродвижущая сила ЭДС
6. mica f) существовать
7. electromotive force g) устройство, прибор
8. flux h) разность потенциалов
9. weaken i) величина, размер
TASK 6. Fill in the gaps and translate the sentences.
1. The unit of measurement of . . . is the Ohm. a) capacitance; b) resistance; c) conductor. 2. The . . . of capacitance is called the farad. a) device; b) po1е; c) unit. 3. The main parts of a . . . are metal plates and insulators. a) resistor; b) amplifier; c) capacitor. 4. The . . . of a variable capacitor move. a) insulators; b) plates; c) units. 5. Both electromotive force and . . . are measured in volts. a) resistance; b) potential difference;с) capacitance. 6. The plates of a . . . cannot be moved. a) variable capacitor; b) fixed capacitor; c) insulator. 7. Capacitance is the . . . of a circuit that opposes any change of voltage in a circuit. a) property; b) application; c) source. 8. A fixed capacitor has . . . produced of paper, mica and other materials. a) insulators; b) plates; c) oscillators.
TASK 7. Transform the sentences from Present Simple Passive into Past (Future) Simple Passive.
1. Fixed capacitors are used in telephone and radio devices. 2. Automatic devices are made in our laboratory. 3. The plates of a condenser are separated by an insulator. 4. Scientific reports are published in our magazine. 5. The two parts of a magnet that show the strongest magnetism are called the North Pole and the South Pole.
TASK 8. Fill in the gaps using Present, Past or Future Simple Passive Voice.
1. This phenomenon … (to study) by a group of scientists two months ago. 2. A device which has the ability to condense a charge of electricity … (to call) a capacitor. 3. A new transmitting station … (to build) in this region next year. 4. Copper … (to use) to produce wire conductors. 5. Yesterday a very interesting experiment … (to make) in our laboratory. 6. The properties of silver … (to discuss) next week.
TASK 9. Fill in the gaps using Present, Past, Future Simple Active or Passive Voice.
1. Every student knows that an insulator … (to call) a dielectric. 2. The engineer … (to find) practical application of these circuits, the results were good. 3. The simplest condenser … (to consist) of two plates separated by an insulator. 4. These three quantities … (to measure) in our experiment next week. 5. Radio … (to invent) in Russia. 6. When the current is small, a galvanometer … (to use). 7. They … (to measure) these quantities tomorrow. 8. This young engineer … (to make) a new device and we used it in our experiment.
TASK 10. Ask questions to the words in bald.
1. Devices which have the ability to condense the charge are called condensers. 2. An ohmmeter is used to measure the value of resistance in a circuit. 3. The proton was discovered by Rutherford. 4. Many technical problems will be solved by Russian scientists in the near future. 5. Electromagnetic waves are used in radio and television transmission. 6. A rheostat is used to change resistance of circuits, and in this way to vary the value of current. 7. The theory of radio-transmitting and radio receiving devices was improved by Russian scientists. 8. Amplifiers are used when we want to make signals bigger.
TASK 11. Listen to the recording and fill in the gaps with numbers and units.
SIMBA ELECTRONICS
AVC 1) … . Ceramic disc capacitor. 2) … per unit.
Non-polarized multilayer ceramic capacitor. Flame-retardant. Typically used for coupling, and bypass applications.
Capacitance: 3) …
Voltage rating: 4) …
Operating temperature range: 5) …
AVP 6) … . Plastic (mylar) capacitor. 6) … per unit.
Non-polarized polyester film (mylar) insulator and metal plates encased within a hard epoxy coating. Coating protects against moisture. Designed for use in general purpose DC applications.
Capacity: 7) …
Voltage rating: 8) …
Operating temperature range: 9) …
AVE 10) … . Electrolytic capacitor. 11) … per unit.
Aluminum capacitors designed for applications needing high capacitance, low cost, and very small size such as in personal computers and medical electronics.
Capacitance: 12) …
Voltage rating: 13) …
Operating temperature range: 14) …
All of our capacitors contain marks indicating, at minimum, their capacitance. Check out our tantalum capacitors and trimmer capacitors on the next page!
UNIT 11
Task 1.Study new words and word combinations.
| mutual induction | ['mjuul ], ['mjutjul] | взаимоиндукция | |
| turn | виток | ||
| step up | повышать | ||
| step down | понижать | ||
| transfer | [træns'f] | передавать | |
| primary winding | ['pramr] | первичная обмотка | |
| secondary winding | ['sekndr] | вторичная обмотка | |
| supply | [s'pla] | поставлять, запас | |
| operate | ['pret] | работать, функционировать | |
| magnetic field | [mæg'netk fild] | магнитное поле | |
| induced voltage | ['vult ], ['vlt] | индуцируемое напряжение | |
| power transmission | передача энергии | ||
| ferromagnetic core | ферромагнитный сердечник | ||
| power grids | энергетические сети | ||
| magnetic flux | магнитный поток |
TASK 2. Read the text and translate it from English into Russian.
TRANSFORMERS
A transformer is a device which is used to transfer electrical energy from one circuit to another. Besides, a transformer is used to change the voltage and current in a circuit. A transformer is based on the fundamental principle of mutual induction. A simple transformer consists of two coils and a core. The coils are called the primary and the secondary. These coils are wound over a common core. Transformers can have either air or magnetic cores. It depends on the frequency at which they are to be operated. The primary winding is connected to the voltage source. It receives energy. The secondary winding is connected to the load resistance and supplies energy to the load. There are two types of transformers: a step-up transformer and a step-down transformer. In a step-down transformer the number of turns in the primary is greater than the number of turns in the secondary. This transformer steps down the voltage. In a step-up transformer the number of turns in the secondary is greater than in the primary. The important thing in transformer design is the insulation of windings. There are 3 main classifications of transformers: for power-frequency circuits, for audio-frequency and for radio frequency.
TASK 3. Complete the sentences.
1. A transformer is a device which is used to . . .
2. A transformer is based on . . .
3. The coils of the transformer are called . . .
4. The primary winding of the transformer is connected . . .
5. The important thing in transformer design is . . .
TASK 4. Answer the following questions and retell the text.
1. What is a transformer used for? 2. What principle is a transformer based on? 3. What cores can transformers have? 4. What is the function of a primary winding? 5. What two types of transformers does the text discuss? 6. What is the important thing in transformer design? 7. What three main classifications of transformers do you know?
TASK 5. Make up the sentences using the following words and word combinations.
A transformer, a device, to transfer electrical energy, to change voltage and current in a circuit, mutual induction, two coils, a core, the primary winding, the secondary winding, to receive energy, to supply energy, a step-up transformer, a step-down transformer, the number of turns, the insulation of windings.
TASK 6. Translate the sentences, pay attention to the degrees of comparison.
The simplest condenser consists of two plates separated by an insulator. 2. In practice the most common types of dielectrics are: air, mica, paper. 3. We think that he is the best inventor of our plant. 4. I work worse than he does. 5. This new device works better that the old one. 6. Scientists try to get better knowledge of the mineral resources of this region. 7. The proton was found to be 1,840 times heavier than the electron. 8. Radio is one of the greatest achievements of modern engineering.
TASK 7. Read the text about transformers and complete it with the following words and phrases.
| magnetic field, winding, mutual induction, conductors |
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled 1) … – the transformer’s coils. A varying current in the first or primary 2) … creates a varying magnetic flux in the transformer’s core, and thus a varying 3) … through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or “voltage” in the secondary winding. This effect is called 4) … .
| number of turns, primary voltage, ferromagnetic core, induced voltage |
If a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the 5) … in the secondary winding(VS) is in proportion to the 6) … (VP), and is given by the ratio of the 7) … in the secondary (NS) to the number of turns in the primary (NP) as follows:
By appropriate selection of the ratio of turns, a transformer thus allows an alternating current (AC) voltage to be “stepped up” by making NS greater than NP, or “stepped down” by making NS less than NP.
In the vast majority of transformers, the windings are coils wound around a 8) … , air-core transformers being a notable exception.
| power transmission, power grids, electronic circuits |
Transformers range in size from a thumbnail-sized coupling transformer hidden inside a stage microphone to huge units weighing hundreds of tons used to interconnect portions of 9) … . All operate with the same basic principles, although the range of designs is wide. While new technologies have eliminated the need for transformers in some 10) … , transformers are still found in nearly all electronic devices designed for household (“mains”) voltage. Transformers are essential for high voltage 11) … , which makes long distance transmission economically practical.
TASK 8. a) Match the names with the descriptions.
Power transformers
Auto transformer
Instrument potential transformer
Distribution transformers