Урок 6. Unit 6.

1. Прочитайте и запомните следующие слова и словосочетания:

a specific current – удельный ток, относительный ток, номинальный ток;

a short-circuit current – ток КЗ;

a rupturing capacity – разрывная мощность, отключающая способность;

a blowout – задувание, гашение;

to extinguish the arc – гасить, погашать;

switch blades – контактный нож, нож выключателя;

to bridge contacts – соединять перемычкой контакты, закорачивать;

a push button – нажимная кнопка;

a remote control type – дистанционного управления;

an arc extinction chamber – дугогасительная камера;

a toggle mechanism – коленчатый механизм;

a transformer bank – трансформаторная группа;

sulphur hexafluoride (SF₆) – элегаз;

an arc quenching quality – качество гашения дуги;

to exhaust – выпускать, выкачивать;

to liquefy – превращать(ся) в жидкость;

a puffer technique – метод прерывистой подкачки;

a clogging effect – эффект закупоривания;

sweeping of the arc – выдувание дуги;

exhausts – выходные отверстия, выхлопные трубы;

to energize – приводить в действие;

against the opposition of – преодолевая сопротивление;

pressure – давление;

a disconnecting switch – размыкающий переключатель, выключатель,

разъединитель.

2. Прочитайте текст 6 “Circuit Breakers”, Part 2. Выпишите из текста все

сочетания, где определения выражено существительными.

5. CIRCUIT BREAKERS

Part 2

A circuit breaker is a switch designed to interrupt a specific current at a specific voltage. The specific current is always the maximum short circuit current that the breaker may be required to interrupt in the particular application under consideration. A three-phase circuit breaker consists of three single-pole switches arranged to operate simultaneously. The interrupting or rupturing capacity of a three-phase breaker is expressed in kilovolt-amperes, and is equal to √3 EI/1,000, where I is the maximum short-circuit current that it can interrupt, and E is the normal line voltage.

Air-break circuit breakers with magnetic blowout are available in various designs for d.c. voltages up to 3 kv and for a.c. voltages up to 34.5 kv. Their rupturing capacities range up to 2.5 million kva, three phase.

Oil circuit breakers have their contacts immersed in oil which helps to extinguish the arc which always forms as the contacts separate. For voltages up to 14.4 kv, the three poles are usually enclosed in a single tank. The three switch blades remain horizontal at all times. When they are raised, they close the three circuits by bridging the stationary contacts. The opening of the breaker therefore produces two arcs in series at each blade. In all cases the breaker is closed against the opposition of a spring and is held closed by a latch. This latch may be tripped by means of a trip coli, energized either automatically by one or more relays or by means of a push button located at any convenient place. When voltage or required rupturing capacity is high, a separate tank is provided for each pole.

The larger circuit breakers are all of remote-control type and are closed by means of a small motor or a solenoid or by compressed air acting on a piston. Small breakers are also often remote-controlled. Oil circuit breakers were at one time standard for all voltages above 600 volts, but new indoor installations are usually air-break up to 34.5 kv and air-blast above 34.5. Oil circuit breakers are still used extensively for outdoor installations, but air-blast circuit breakers are competing successfully in this field.

Air-blast circuit breakers rely mainly on a violent blast of compressed air to extinguish the arc. These breakers require a continuously available supply of compressed air at pressures ranging to 800 lb per sq. in. This supply of compressed air is used not only to blow out the arc but also to operate opening and closing mechanisms.

The circuit breaker is opened by sending a powerful blast of air into the arc extinction chamber. The tube like moving contact is blown to the left against the opposition of a spiral spring, and the arc that forms as the contacts separate is blown out through the hollow contact. The duration of the air blast is only a fraction of a second, and at its conclusion the spiral spring slams the contacts closed again. In the brief interval of time during which the contacts are open, a coordinated toggle mechanism opens the external disconnecting switch, so that the reclosing of the contacts in the arc extinction chamber does not reestablish the circuit.

The 230 kv air-blast circuit breakers at one of the hydroelectric plants have eight of these arc extinction chambers connected in series in each of the three conductors. Since the eight chambers operate simultaneously, it follows that with ideal operation only one-eighth of the voltage appeared across the chamber. The air-blast breakers do not make use of coordinated disconnects.

As soon as the arc is extinguished, the exhausts are closed and the air-blast pressure is maintained so as to hold the moving contacts open.

Disconnecting switches. Knife switches (рубильники) are used at all voltages and currents, but except when the power is very small they must not be opened while current is flowing. They are used to isolate apparatus after the circuit has been opened by a circuit breaker. Switches that are used in this way are called disconnecting switches, or isolating switches, or disconnects. In general, every important piece of equipment, such as a circuit breaker or a transformer bank, has a three-pole disconnect on each side of it, so that maintenance and repairs can be carried out in safety. The smaller disconnecting switches are opened and closed by means of a long wooden stick with a hook attached to one end, the larger ones by a motor-driven mechanism.

3. Найдите правильное толкование следующих слов:

1) excellent (qualities) a) very poor

b) very good

2) advanced (technology) a) technology that is new

b) technology that is widely used

3) to obtain a) to connect

b) to get, to receive

4) to restore a) to make, to produce

b) to make normal again, to bring back to a

former condition

5) to cause (some effect) a) to make happen

b) to make strong

4. Образуйте возможные словосочетания и переведите их.

1) specified a) tank

2) short-circuit b) application

3) rupturing c) current

4) stationary d) installation

5) outdoor e) contacts

6) compressed f) capacity

7) opening g) contacts

8) moving h) mechanism

9) separate i) air

10)particular j) voltage

5. Закончите предложения, выбрав правильный вариант.

1) A three-phase circuit breaker consists of three single-pole switches arranged to operate

a) simultaneously b) one at a time

2) Oil circuit breakers have their contacts immersed in oil, which helps

a) to produce the arc b) to extinguish the arc

3) When the voltage or required rupturing capacity is high,

a) a separate tank is provided for each pole

b) no separate tank is provided for a pole

4) The supply of compressed air in air-blast circuit breakers is used not only to blow out the arc, but also

a) to distribute the current

b) to operate the opening and closing mechanism

6. Найдите в тексте информацию и расскажите о принципе действия

масляных и воздушно-взрывных выключателей.

7. Переведите текст на русский язык.