Виконання вправ на закріплення граматичної теми
Вправа 6. Складіть питання до кожного члена речення.
Contactless switches are intended for switching of chains of management by means of electromagnetic relays or contactless logical elements which is carried out under the influence of the operating element.
On a way of impact on a sensitive element contactless traveling switches can be divided into switches of mechanical and parametrical action.
Electric characteristics of contactless traveling switches include the demanded parameters of the power supply (power line) and load characteristics.
The electric schematic diagram includes the generator and the trigger on transistors.
The main characteristic of the face switch is the maximum distance of influence, i.e. the maximum distance between a sensitive surface of the switch and the operating element at which change of its switching state is possible.
Заняття 52
Тема: Апаратура керування та захисту електроприводів: кнопкові пости, рубильники, контроери, запобіжники
Граматичний матеріал: Порядок слів у спонукальних та окличних реченнях
Вправа 1. Прочитайте таперекладіть слова за допомогою словника.
motionless parts [ˈməʊʃənlɪs pɑːts]
three-arms (shoulder) lever [θriː-ɑːmz (ˈʃəʊldə) ˈliːvə ]
axis [ˈæksɪs]
contact-maker [ˈkɒntækt-ˈmeɪkə] з
brass contact plate [brɑːs ˈkɒntækt pleɪt]
spiral spring [ˈspaɪərəl sprɪŋ ]
screw [skruː]
wire [ˈwaɪə]
tension [ˈtɛnʃən]
strengthened [ˈstrɛŋθənd]
nuts [ nʌts]
at short circuit [æt ʃɔːt ˈsɜːkɪt]
cross over knife switch [krɒs ˈəʊvə naɪf swɪʧ ]
rotation sense [rəʊˈteɪʃən sɛns]
handhold [ˈhændhəʊld ]
fuses [ˈfjuːzɪz ]
admissible value [ədˈmɪsəbl ˈvæljuː]
safety plugs [ˈseɪfti plʌgz ]
melting insertion [ˈmɛltɪŋ ɪnˈsɜːʃən]
cut-outs [kʌt-aʊts]
Вправа 2. Прочитайте та перекладіть текст українською.
Push-Button Switch, Knife Switches, Controllers, Fuses
PUSH-BUTTON SWITCH
The rotary switch (Fig.1) serves for switch on and switch off the receivers of electric energy up to 220 V.
Fig.1
The
rotary
switch
foundation; 2, 4 - stationary spring contacts; 3 – drum; 5 – contacts for joining of wires; 6 - clamping screw; 7 - contact plate.
The simplest switch of a low voltage calculated on low power is the push-button switch (Fig. 2). It consists of mobile and motionless parts.
Fig.2
The
push-button switch
rotary part; б) the stationary part
The mobile part (above) has two buttons 1, three-arms lever 3 fixed on axis 2, and a contact-maker 4 with a brass contact plate 5. In the case of a contact-maker a spiral spring 6 and a steel ball 7 are located.
The motionless part (below) consists of two contacts with contact springs 8 which join by means of screws 10 of a wire 9 from an electric circuit.
When pressing the button 1 located at the left the three-arms lever 3.1 falls down. His right shoulder together with the second button rises up. At the same time average third shoulder of the lever works through a ball 7 and a spiral spring in on a contact-maker 4, moving it to the right. The last the plate 5 connects contact springs of the 8th motionless part of the switch and thus closes a chain of wires 9.
When pressing the button located on the right the contact-maker moves to the left and disconnects a chain.
KNIFE SWITCHES
For switch on and switch off any electrical units with tension to 500 V at the currents exceeding 6 A apply knife switches.
There are unipolar, bipolar and triple-pole knife switches which are mounted on boards.
The main parts of a triple-pole knife switch (Fig. 3a) are copper knives 1 which can turn on the axes 5 strengthened in motionless contacts 4.
Fig.3 Knife switches
a) a triple-pole knife switch; б) crossover switch
Wires from the receiver of electric energy join bolts of contacts by means of nuts. At short circuit of a chain copper knives 1 enter intervals between the springing contacts 3 to which clips wires 2 from an electric circuit are connected.
Along with usual knife switches apply knife switches which are called also cross over (Fig. 3б).
Switches, except the top springing contacts, have the same number of the lower contacts. Knives of a cross over knife switch can be connected both with top and to the lower contacts.
By safety regulations knife switches and switches are closed by protection covers.
CONTROLLERS
For making several switches at the same time in electrical circuits in case of start-up of electrical machines, regulation of speed, change of a rotation sense of electro motors it is used controllers.
The controller (Fig.4) consists of copper segments 1 (segments of the rings) strengthened on a shaft 2 of insulating material. The segments which are mobile contacts move in case of turn of the handhold 3 together with shaft.
Except mobile contacts, the controller has the fixed springing contacts 4 isolated among themselves.
Number of segments of the controller equally to number of its springing contacts which wires are going from the electrical machines, rheostats and other devices controlled by the controller join.
In case of turn of a shaft one segments of the controller are shorted with fixed contacts, and others are disconnected. By such way difficult switches in electrical circuits are carried out.
FUSES
In case of short circuit, and also in case of an overload circuit the electric current proceeding on the wires, electrical machines and instruments switched on in a circuit increases and exceeds admissible value. Wires of a circuit overheat, and their insulation can light up, and electrical machines and instruments can fail.
For protection of electrical circuits against short-circuit currents of the long overloads sequentially with receivers of electrical energy safety plugs turn on. Their operation is based on use of thermal action of current.
Each fuse shall withstand unlimited time the current intensity specified on it. In case of relocation of this current intensity the melting insertion melts the quicker, than more overload.
If in an electrical circuit in case of a uniform load (without current intensity changes) labor of current I=10 A, it is impossible to turn on the fuse expected smaller current intensity in such circuit.
In case of a fuse choice for an electrical circuit in which will turn on electro motors, it is necessary to consider the short-time force of a starting current exceeding labor of current approximately by 5-7 times. For this reason that the fuse doesn't interrupt a circuit in case of each start-up of the engine, it is necessary to set the fuse on the rated current intensity making about 40% of a starting current of the engine. It must be kept in mind that the fuse selected in such way protects the engine only from short-circuit currents, but doesn't protect it from the long overload. For such protection of the engine time cut-outs and the relay serve.
In Fig.5 Fuses of different construction are shown
Вправа 3. Дайте відповіді на питання.
What is the simplest on/off switch?
What does it consist of?
When do we use knife switches?
When do we use cross over knife switch?
What must we do by safety regulations?
When do we use controllers?
What does the controller consist of?
How are difficult switches in electrical circuits carried out?
When does the electrical current exceed admissible value?
Why do we use fuses?
Вправа 4. Вставте замість крапок необхідне за значенням слово або висловлювання.
It consists of … and motionless parts.
His … … together with the second button rises up.
When … … … located on the right the contact-maker moves to the left and disconnects a chain.
For switch on and switch off any … … with tension to 500 V at the currents exceeding 6 A apply knife switches.
Wires from the receiver of … … join bolts of contacts by means of nuts.
Knives of a cross over knife switch … … … both with top and to the lower contacts.
Except mobile contacts, the controller has the fixed … … isolated among themselves.
In case of turn of a shaft … … of the controller are shorted with fixed contacts, and others are disconnected.
Wires of a circuit overheat, and their insulation can light up, and … … and instruments can fail.
For such protection of the engine time … … … … serve.
(one segments, cut-outs and the relay, electrical machines, mobile, electric energy, pressing the button, right shoulder, electrical units, can be connected, springing contacts).
Вправа 5. Знайдіть еквівалентні пари.
А. поворотний вимикач, кнопковий вимикач, рухома частина, контактні пружини, електрична мережа, замикати ланцюг, розмикати ланцюг, змонтовані на щитах, мідні ножі, електрична енергія, захисний кожух, для декількох переключень, при пуску електричних машин, регулювання швидкості, мідні сегменти, ізолюючий матеріал, вал, перенавантаження мережі, прибори, для захисту електричних ланцюгів, плавка вставка.
B. insulating material, melting insertion, an overload circuit, devices, for protection of electrical circuits, shaft, copper segments, several switches, regulation of speed, start-up of electrical machines, electrical energy, protection covers, copper knives,
are mounted on boards, rotary switch, push-button switch, motion part, contact springs, electrical circuit, to close a chain, to disconnect a chain.
Граматичний матеріал: Порядок слів у спонукальних та окличних реченнях
Наказові речення в англійській мові (або, як їх ще називають, спонукальні речення) висловлюють спонукання до певної дії, прохання, наказ, а в негативній формі – заборону.
Наказове речення в англійській мові має звичайний, прямий порядок слів, але починається з дієслова, а іноді складається з нього одного:
Give me that! – Дай мені це!
Run! – Біжи!
Для пом’якшення наказу і перетворення його в прохання в кінці речення можна вжити will you (won’t you), would you (wouldn’t you):
Do as much as you can, will you? – Зроби так багато, як зможеш, добре?
Також для цього можна використовувати конструкцію let’s + інфінітив англійського дієслова без частки to:
Let’s make a pizza! – Давайте зробимо піцу!
Окличним може стати будь-який тип речення, якщо він буде виголошений з емоційним забарвленням:
I’m thirsty! – Мене мучить спрага!
Be quiet, Jack!
What’s is that?! – Що це?!
Для додаткового підсилення емоції в окличних реченнях можуть використовуватися слова what, that та how:
What a garden you have! – Який в тебе сад!
That‘s right! – Це вірно!
How it was?! – Як пройшло?
That‘s pity! – От жаль!
What‘s going on?! – Що відбувається?!
Але окличні речення можуть включати в себе лише 1 слово або словосполучення:
Awesome! – Класно!
Wonderful! – Чудово!
Wow! – Супер!
Well done! – Добре зроблено!