Виконання вправ на закріплення граматичної теми
Вправа 6. Перекладіть речення.
Давай зберемо електричний ланцюг.
Зробіть заземлення.
Використовуйте пакетні вимикачі.
Давайте використаємо автоматні вимикачі.
Не треба робити цього!
Перевірте роботу шляхових перемикачів.
Заняття 53
Тема: Апаратура керування та захисту електроприводів: автоматичні вимикачі, електромагнітні пускачі, контактори, теплове реле
Граматичний матеріал: Реферативний переклад
Вправа 1. Прочитайте та перекладіть слова за допомогою словника.
switches machine guns [ˈswɪʧɪz məˈʃiːn gʌnz]
reach [riːʧ ]
anchor-latch [ˈæŋkə-læʧ]
core [kɔː]
adjust [əˈʤʌst]
shutdown [ˈʃʌtdaʊn]
on a certain current [ɒn ə ˈsɜːtn ˈkʌrənt]
widespread [ˈwaɪdsprɛd]
contactor [ˈkɒntæktə]
excite [ɪkˈsaɪt]
operational electric current ˌ[ɒpəˈreɪʃənl ɪˈlɛktrɪk ˈkʌrənt]
usual type [ˈjuːʒʊəl taɪp]
anchor [ˈæŋkə ]
clips[klɪps]
winding [ˈwɪndɪŋ ]
pivot-center [ˈpɪvət-ˈsɛntə ]
flexible wire [ˈflɛksəbl ˈwaɪə]
become demagnetized [bɪˈkʌm ˌdiːˈmægnɪtaɪzd]
rectilinearly [ˌrɛktɪˈlɪnɪəli]
movable frame [ˈmuːvəbl freɪm]
crossbeam [ˈkrɒsbiːm]
densely [ˈdɛnsli]
magnetic actuator [mægˈnɛtɪk ˈæktjʊeɪtə]
top basis [tɒp ˈbeɪsɪs]
three contact crossing points plates [θriː ˈkɒntækt ˈkrɒsɪŋ pɔɪnts pleɪts]
thermal relay [ˈθɜːməl riːˈleɪ]
thermo switch [ˈθɜːməʊ swɪʧ]
extension of metal[ ɪksˈtɛnʃən ɒv ˈmɛtl]
linear expansion [ˈlɪnɪər ɪksˈpænʃən]
brass[ brɑːs]
sequentially [sɪˈkwɛnʃəli ]
be bend [biː bɛnd]
intermittently [ɪntə(ː)ˈmɪtəntli]
curve [kɜːv ]
pressure gages [ˈprɛʃə ˈgeɪʤɪz]
Вправа 2. Прочитайте та перекладіть текст українською.
Switches Machine Guns, Electromagnetic Actuators,
Contactors, Thermal Relay
SWITCHES MACHINE GUNS
For automatic switching off and protection to electric circuits switches machine guns use at violation of normal operating conditions. They are two types: maximum and minimum.
The machine gun which is disconnecting a circuit when current in it reaches size, bigger than admissible, it is called maximum. The main parts of such machine gun (Fig.1 a) are: electromagnet, anchor-latch and switch.
Fig. 1a) Fig. 1б)
Arrangement of switch machine of:
а) maximum; б) minimum
When current in a circuit of the machine gun exceeds the admissible size, an electromagnet 1 attracts an anchor latch 2. The knife of the switch 3 is released and under the influence of a spring 4 automatically disconnects a circuit in which it is switched on the machine gun.
Repeated turning on of the machine gun is made manually.
The machine gun which is disconnecting a circuit when tension in it becomes less admissible is called minimum (Fig. 1б).
When passes current in a circuit of the machine gun less admissible, the core of an electromagnet 1 isn't able to hold vertically an anchor latch shoulder. As a result of it the spring 5 delays an anchor from the electromagnet core, and a latch 2, rising up, releases a knife of the switch 3 which under the influence of a spring 4 disconnects the circuit which is protected by the machine gun.
Machine guns can be adjusted on a certain current at which there is a shutdown. The biggest advantage of machine guns is the accuracy of their installation on a certain current, considerably bigger than at protection of circuit by fuses.
CONTACTORS
The most widespread device for remote short circuit and disconnection of electric chains is the contactor.
Unlike devices in which switching on and switching off of electric chains make manually (knife switches), in contactors these operations are happen automatically under the influence of the magnetic field excited at switching on of operational electric current.
Two main types of contactors differ: rotary and usual type.
The rotary contactor (Fig. 2a) consists of an electromagnet 1, the anchor 7 located on axis 6, the main contacts 2 and clips 3 and 4 for accession of wires of the power supply network. All parts of the contactor are strengthened on the panel 8.
Arrangement of contactors:
Fig. 2 a) rotary; 2 б) usual type
When operational current passes on a winding of an electromagnet of the contactor, his core is magnetized and attracts an anchor. An anchor, turning round its pivot-center, closes the main contacts.
Current in the circuit created by the contactor passes from a clip 3 through the main contacts 2 and a flexible wire 5 to a clip 4, and from here to the electrical machine which is operated by the contactor.
At disconnection of a chain of an electromagnet its core become demagnetized and the anchor disconnects the main contacts.
In the usual type contactor (Fig. 2б) the mobile part of magnetic system (anchor) doesn't turn on an axis as in the contactor of rotary type, and moves rectilinearly.
The contactor consists of the Sh-shaped core 10, an electromagnet 11, an anchor 9, the movable frame 12, a crossbeam 13 of insulating material, double contacts of 14 and motionless contacts 15 which wires join of an electric chain. When on a winding of an electromagnet of the usual type contactor electric current proceeds, the anchor is attracted to the motionless core and rises up, entraining the movable frame and connect them to the double contacts come on a crossbeam which densely touch two motionless contacts. There is a short circuit of the chain operated by the contactor.
Contactors for chains of a direct current are unipolar, and contactors of three-phase alternating current is triple-pole.
Contactors widely apply to control of electrical units at plants and factories.
MAGNETIC ACTUATOR
Remote control of electric motors of three-phase alternating current is exercised by means of magnetic actuators — more difficult devices in which triple-pole contactors enter.
The magnetic actuator of usual type (Fig. 3a) has an electromagnet 1 with the steel core attached to the top basis 2. The anchor 5 is located below on which three contact crossing points plates isolated one from another 4 are strengthened. The basis 2 actuators is supplied with contacts 3 which the wires of L1, L2, L3 from a circuit of three-phase alternating current and a wire going from the electric motor join.
Magnetic actuator
Fig. 3 a) general appearance; 3 б) the scheme of turn on
When passing operational electric current through a winding of an electromagnet the magnetic field and an anchor is excited attracted to the core. Contact plates crossing points of an anchor connect among themselves contacts to which wires from a circuit of three-phase alternating current are connected and from the electric motor. At switching off of current the anchor under the influence of a body weight falls and contact plates crossing points disconnect the engine from a circuit.
Start-up of the engine by means of the magnetic actuator can be carried out, having included it according to the scheme provided on Fig.3. Contacts of the magnetic actuator 1, 2, 3 are normally opened. The EM actuator electromagnet is attached by one end to contact of the Start-up button, and another - to a network L2 wire. Contacts of the Feet button are normally closed, and contacts of the Start-up button are opened. Block contacts of BQ are connected parallel to contacts of the Start-up and Stop buttons.
Using two triple-pole contactors, it is possible to turn on the asynchronous engine so that with their help it is possible to make an engine reversal.
The push-button station of the reversal magnetic actuator consists of three buttons: "Forward", "Back" and "Stop".
By pressing the Forward button the anchor of an electromagnet of one contactor will be attracted to the core and will close the main contacts of the actuator on which current will come to the electric motor.
By pressing the Stop button the chain of this electromagnet owing to what the anchor disconnects the main contacts and windings of the engine from circuit wires is disconnected.
For change of the direction of rotation of the engine press the Back button. Thus the electromagnet of the second contactor joins. Current from a circuit comes to engine windings through the main contacts of the second actuator.
THERMAL RELAY
Thermal call the relay reacting to change of temperature (thermo switch). Action of a thermo switch is based on extension of metal in case of its heating up.
Bimetallic thermal relays were widely adopted. The working part of such relay represents the bimetal plate consisting of two metals with different temperature coefficients of the linear expansion. Materials for plates select so that they had perhaps big difference of expansion ratios, for example copper - steel, steel - nickel, invar - brass.
In case of the current overloads the thermal maximum relay use (Fig. 4) to protect of electric motors. The electric heater of 1 thermal relay is the perceiving part. The bimetallic plate 2 is used as the intermediate part, and as an execution part contacts 7 serve. The heater joins sequentially in an engine circuit, and contacts - in a circuit of an electromagnet of the actuator making start-up of the engine.
In case of a normal load the bimetallic plate is bent. Thus the lever 3 rests the upper shoulder against a plate 2, and his lower shoulder shorts contacts of 7 relays.
When current in a heater exceeds admissible value, the bimetallic plate 2 is bent towards metal with smaller coefficient of thermal extension, i.e. up. Then the upper lever arm 3 under the influence of a spring 5 is turned on axis 4 to the left, the lower shoulder - to the right, and contacts of the relay disconnect a circuit in which they are included.
Thermal relay
a) thermal; б) temperature-current
For making of the relay into working position click thus the appendix of the 6th lever 3 goes to the left, and his upper shoulder departs to the right and is set as is shown in Fig. 4a.
In fig.4б, the temperature and current TT-1 relay is figured which is intended for protection against overheating of windings of asynchronous single-phase short-circuited electromotors with power up to 600 W of 127 and 220 V.
The relay has a bimetallic element which when heating for a certain temperature intermittently changes the direction of the curve, and when cooling also intermittently returns to the previous position.
The relay is mounted directly on the engine. Its contacts join in an engine supply circuit. The same circuit sequentially turns on the non- chromic heater.
In case of an engine overload, under the influence of heating of the non- chromic heater the current proceeding on engine windings, the bimetallic element of the relay works and disconnects an engine circuit.
Temperature of actuating of a bimetallic element of the relay about 120 °. Return temperature about 80 °. The weight of the relay is no more than 12 g.
Such thermal relays supply magnetic actuators, oily pressure gages, thermometers of the cooling system of cars and many other devices.
Вправа 3. Дайте відповіді на питання.
What do we use to protect electrical circuits?
What are their types?
What are the main parts of a maximum machine gun?
How is repeated turning on of the machine gun made?
When do we call machine gun minimum?
What are the main advantages of switches machine guns?
What do we call contactors?
What are their types?
Where do we use contactors?
When do we use magnetic actuator?
On what action is thermo switch based?
What kind of thermo switch has a widespread?
Where is the relay mounted directly?
What is temperature of actuating of a bimetallic element of the relay?
What is the return temperature?
What do supply such thermal relays?
Вправа 4. Перекладіть письмово словосполучення, користуючись текстом.
Порушення нормальних робочих умов, вимикати ланцюг, основні частини, електромагніт, вимикач, притягувати якір-клямку, менш допустима напруга, певна сила струму, плавкі запобіжники, дистанційне замикання та розмикання електричних ланцюгів, під дією магнітного поля, намагнічуватися, для ланцюгів постійного струму, більш складні пристрої, можна вмикати асинхронний двигун, обмотка двигуна, біметалічні теплові реле, коефіцієнт розширення, пуск двигуна.
Вправа 5. Замість крапок вставте необхідне за смислом слово, перелік яких поданий нижче.
The machine gun which … … a circuit when current in it reaches size, bigger than admissible, it is called maximum.
… … … of such machine gun are: electromagnet, anchor-latch and switch.
The machine gun which is disconnecting a circuit when … in it becomes less admissible is called minimum.
The biggest … of machine guns is the accuracy of their installation on a certain current, considerably bigger than at protection of circuit by fuses.
… … … consists of an electromagnet, the anchor located on axis, the main contacts and clips for accession of wires of the power supply network. All parts of the contactor are strengthened on the panel.
All parts of the contactor … … on the panel.
There is a … … of the chain operated by the contactor.
Remote control of electric motors of three-phase … … is exercised by means of magnetic actuators — more difficult devices in which triple-pole contactors enter.
When passing operational … … through a winding of an electromagnet the magnetic field and an anchor is excited attracted to the core.
Using two triple-pole contactors, it is possible to turn on the … … so that with their help it is possible to make an engine reversal.
Current from a circuit comes to engine … through the main contacts of the second actuator.
… … … select so that they had perhaps big difference of expansion ratios, for example copper — steel, steel — nickel, invar — brass.
In case of the current overloads the thermal maximum relay use … of electric motors.
Such thermal relays supply magnetic actuators, … … …, thermometers of the cooling system of cars and many other devices.
The relay has a bimetallic element in which when heating for a certain temperature intermittently changes the direction of the curve, and when cooling also intermittently returns to the … … .
(electric current, materials for plates, the rotary contactor, are strengthened,
asynchronous engine, previous position, oily pressure gages, is disconnecting,
advantage, the main parts, short circuit, tension, alternating current, windings,
to protect).
Вправа 6. Виберіть правильну відповідь (ідиому).
1. Tom eats like a … . He ate all of the roast beef, and most of the chocolate cake too.
cow
horse
lion
whale
2. I don't like this situation. I don't trust those people, and I smell a … .
cat
mouse
rat
skunk
3. We were scared and didn't know what to do. Then Mike decided to … and tell the boss everything.
take the bear by the tooth
take the bull by the horns
take the lion by the muzzle
take the monkey by the tail
4. She doesn't need it, but she doesn't let me have it either. She behaves like a … in the manger.
bear
dog
fox
wolf
5. I didn't like driving in that city. Traffic was too heavy there. Wild drivers and road … were also a problem.
bears
foxes
hogs
weasels
6. My neighbor is as strong as … . I couldn't even move that box, and he picked it up and carried it out.
an elephant
a gorilla
an ox
a tiger
7. He is not rich, and his family is large. He has to work hard to keep the … from the door.
jackal
lion
tiger
wolf
8. In my opinion, buying a used car without consulting a good car mechanic first is like buying a … in a poke.
cat
dog
goat
pig
9. You can sit here till the … come home, but he won't come out and talk with you.
bulls
camels
cows
sheep
10. The hall was so packed with people that there was not enough room to swing a … .
cat
dog
mouse
rabbit
Граматичний матеріал: Реферативний переклад
Реферати́вний пере́клад — різновид перекладу, при якому відбувається стиснення основного змісту вихідного тексту на одній мові засобами іншої. З однієї сторони, реферативний переклад являє собою форму реферування та змістовну редукцію тексту. З іншої сторони, він підпадає під означення перекладу як передачі інформації, яка міститься у деякому творі, засобами іншої мови.