ВИВЧЕННЯ ТЕКСТУ ЗА ФАХОМ

2.9 Types of Fuses

Fuses are used to protect circuits against overcurrents. In case of an overcurrent, the fuse link made of copper, Zink or lead melts and opens the circuit. Zink, lead and their alloys are known to melt at a rather low temperature (200° to 240°C). These metais having a low conductivity, fuse links made their must have a large cross-sectional area. Copper fuse links have a good conductivity, but they melt at a rather high temperature. As to silver fuse links, they are rather expensive and are known to be used at voltages over 1,000 V and low currents. Most commonly, use is made of copper fuse links silvered for protection against oxidation.

There are several types of fuses in use nowadays. Of them, a plug-type fuse has a porcelain container. Fuses of this type are used for voltages up to 380 V and currents up to 60 amp.

As to a sand fuse, it is used for voltages up to 500 V at currents from 100 to 60 amp,

!. Складпгь словник незнайомих сл!в за зразком:

То be made of

То melt

Lead

Alloy

Low conductivity

Cross-sectional area

Good conductivity

High temperature

Fuse link

Overcurrent

Oxidation Plug-type fuse To be expensive Low current Sand Voltage

П. Прочитайте та перекладпъ текст (усно)

III. Дайте в'щповщь на запитання, використовуючи активну лексику
урока

1. For what purpose are fuses used?

2. What metals are melt at rather low temperature? Do these metals have a low conductivity?

3. What conductivity have copper fuse links? Are they melt at a rather low temperature?

4. Are silver fuse links expensive? When are they used?

5. What are the wide - spread fuse links?

6. What are the types of fuses use nowadays? For what voltage are they used?

IV. Доповнпъ речения словами зпдно з текстом.

1. _______ metals having a low conductivity.

2. Fuses are used_______ against overcurrents.

3. Copper fuse links have_____ conductivity.

4. _______ has a porcelain container.

5. Sand fuse is used for voltage up to____.

6. A plug-type fuse has a____ __.

■

V. Вкаж!ть час та стан присудка. Переклад^ь речения.

1. There are several types of fuse in use nowadays.

2. Zink, lead are know as the metals with a low conductivity.

3. Sand fuse is used for voltage up to 500 V at current from 100 to 600 amp.

4. Copper fuse links are used at voltage over 1,000 V and low current.

V.Fill in the verbs "to utilize", "to convert", "to deliver":

1. Primary cells... electric power. 2. Different kinds of energy can be... into electric energy. 3. Protecting devices should be... in any circuit.

VXHave a talk with your groupmate. Use in your answers "certainly", "I suppose" "I don't know":

1. Should every electric device be protected? 2. Do primary cells deliver different forms of energy? 3 Is a switch used in every circuit? 4. Are ruses utilized in all the circuits? 5. Can thermal energy be converted into mechanical energy? 6. Can metals have amorphous structure?

УП. Translate the sentences into Russian. Mind "etc. (et cetera)" and "in addition to":

1. Electric circuits can include cells, resistors, capacitors, fuses, etc. 2. In addition to fuses relays are
also used as electric circuit protection devices. 3. Electric energy can be converted into light, heat, mechanical
energy, thermal energy, etc. 4. In addition to solid insulators liquid insulators are also widely used in this
system.

Вправа 1

Дайте відповіді на питання:

- What foreign language do you study at college?

Вправа 2

Прочитайте та перекладіть текст. Знайдіть у тексті речення з неозначеними часовими формами дієслова.

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