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ΑΓΓΛΙΚΑ ΙΙΙ Ενότητα 9: Electric Meters: Measurement of Current Σταυρούλα Ταβουλτζίδου Τμήμα Ηλεκτρολόγων Μηχανικών ΤΕ Άδειες Χρήσης • Το παρόν εκπαιδευτικό υλικό υπόκειται σε άδειες χρήσης Creative Commons. • Για εκπαιδευτικό υλικό, όπως εικόνες, που υπόκειται σε άλλου τύπου άδειας χρήσης, η άδεια χρήσης αναφέρεται ρητώς. Χρηματοδότηση • Το παρόν εκπαιδευτικό υλικό έχει αναπτυχθεί στα πλαίσια του εκπαιδευτικού έργου του διδάσκοντα. • Το έργο «Ανοικτά Ακαδημαϊκά Μαθήματα στο TEI Δυτικής Μακεδονίας και στην Ανώτατη Εκκλησιαστική Ακαδημία Θεσσαλονίκης» έχει χρηματοδοτήσει μόνο τη αναδιαμόρφωση του εκπαιδευτικού υλικού. • Το έργο υλοποιείται στο πλαίσιο του Επιχειρησιακού Προγράμματος «Εκπαίδευση και Δια Βίου Μάθηση» και συγχρηματοδοτείται από την Ευρωπαϊκή Ένωση (Ευρωπαϊκό Κοινωνικό Ταμείο) και από εθνικούς πόρους. 2 Περιεχόμενα 1. Σκοποί ενότητας ................................................................................................ 4 2. Περιεχόμενα ενότητας........................................................................................ 4 3. PART I: WARMING UP ..................................................................................... 4 4. PART II: READING AND COMPREHENSION ................................................... 4 5. PART III. INFORMATION TRANSFER – MATCHING ....................................... 8 6. PART IV. PRACTISING GRAMMATICAL STRUCTURES ................................. 8 7. Glossary .......................................................................................................... 10 8. Βιβλιογραφία ................................................................................................... 12 9. Παράρτημα ...................................................................................................... 13 Περιεχόμενα εικόνων Εικόνα 1: Electric Meters. .......................................................................................... 5 Εικόνα 2: Match the words on the left with their synonyms on the right. .................... 7 Εικόνα 3: Exercise with vocabulary expansion. ......................................................... 7 Εικόνα 4: Information transfer.................................................................................... 8 Εικόνα 5: Grammatical structures exercise.............................................................. 10 Περιεχόμενα Πινάκων Πίνακας 1: Glossary. ............................................................................................... 10 3 1. Σκοποί ενότητας Εισαγωγή στην ορολογία των μηχανικών στην θεματολογία Electric Meters: Measurement of Current. 2. Περιεχόμενα ενότητας PART I: WARMING UP. PART II: READING AND COMPREHENSION. PART III. INFORMATION TRANSFER – MATCHING. PART IV. PRACTISING GRAMMATICAL STRUCTURES. 3. PART I: WARMING UP Read the text that follows to get a general idea of what it is about. Then try to answer the following questions. Remember you do not have to understand every word to do so. 1. What are electric meters used for? 2. Which are the main instruments used to detect and measure current? 3. Who was the first to devise a reflecting galvanometer? 4. What kind of currents do ordinary galvanometers measure? 4. PART II: READING AND COMPREHENSION Electric Meters are instruments for measuring and indicating magnitudes of electrical values, such as current, charge, potential, and power, and the electrical characteristics of circuits, such as resistance, capacitance, and inductance. The information is usually presented in terms of defined, standard electrical units, which principally are the ohm, volt, ampere, coulomb, henry, farad, watt, and joule. Given that all forms of matter exhibit one or more electrical characteristics, electrical measurements may be taken from an essentially unlimited number of sources. 4 Εικόνα 1: Electric Meters. Source: Microsoft Corporation (1998). Measurements of Current. Galvanometers are the main instruments used to detect and measure current. They depend on the fact that force is generated by an electric current flowing in a magnetic field. The mechanism of the galvanometer is so arranged that a small permanent magnet or electromagnet sets up a magnetic field that generates a force when current flows in a wire coil adjacent to the magnet. Either the magnet or the adjacent coil may be movable. The force deflects the movable member by an amount proportional to the strength of the current. The movable member may have a pointer or some other device to enable the amount of deflection to be read on a calibrated scale. In the D'Arsonval galvanometer, a small mirror attached to a movable coil reflects a beam of light on a scale about 1 m (about 3 ft) away from the instrument. This arrangement involves less inertia and friction than does a pointer, and consequently, greater accuracy is achieved. The instrument is named after the French biologist and physicist Jacques d'Arsonval, who devised the first reflecting galvanometer. He also conducted experiments with the mechanical equivalent of heat and in the highfrequency oscillating current of low voltage and high amperage, D'Arsonval current, used in the treatment of certain diseases (diathermy treatment). The addition of a scale and proper calibration converts a galvanometer into an ammeter, the instrument used for measuring electric current in amperes; D'Arsonval was also responsible for inventing a direct-current (DC) ammeter. Only a limited amount of current can be passed through the fine wire of a galvanometer coil. When large currents must be measured, a shunt of low resistance is attached across the terminals of the meter. Most of the current is bypassed 5 through this shunt resistance, but the small current flowing through the meter is still proportional to the total current. By taking advantage of this proportionality, a galvanometer can be used to measure currents of hundreds of amperes. Galvanometers are usually named according to the magnitude of the currents they will measure. A microammeter is calibrated in millionths of an ampere and a milliammeter in thousandths of an ampere. Ordinary galvanometers cannot be used for the measurement of an alternating current (AC), because the alternation of the current would produce deflection in both directions. An adaptation of the galvanometer, however, called an electrodynamometer, can be used to measure alternating currents by means of electromagnetic deflection. In this meter a fixed coil, in series with the moving coil, is employed in place of the permanent magnet of the galvanometer. Because the current in the fixed and moving coils reverses at the same instant, the deflection of the moving coil is always in the same direction, and the meter gives a constant current reading. Meters of this type can also be used to measure direct currents. Another form of electromagnetic meter is the iron-vane meter or soft-iron meter. In this device two vanes of soft iron, one fixed and one pivoted, are placed between the poles of a long, cylindrical coil through which is passed the current to be measured. The current induces magnetism in the two vanes, causing the same deflection no matter what the direction of the current. The amount of the current is ascertained by measuring the deflection of the moving vane. Meters that depend on the heating effect of an electric current are used to measure alternating current of high frequency. In thermocouple meters the current passes through a fine wire that heats a thermocouple junction; the electricity generated by the thermocouple is measured by an ordinary galvanometer. In hot-wire meters the current passes through a thin wire that heats and stretches. This wire is mechanically linked to a pointer that moves over a scale calibrated in terms of current. Source: "Electric Meters," Microsoft (R) Encarta. Copyright (c) 1998 Microsoft Corporation. Copyright (c) 1998 Funk & Wagnall's Corporation. II.2. SCANNING- CHECKING FACTS AND IDEAS. Decide if these statements are TRUE or FALSE. Quote from the passage to support your decisions. 1. Electric Meters are instruments for measuring and indicating magnitudes of electrical values. 2. Electrical measurements may be taken from an essentially limited number of sources. 3. Galvanometers are the only instruments used to detect and measure current. 4. D'Arsonval was also responsible for inventing a direct-current (DC) ammeter. 5. Ordinary galvanometers can be used for the measurement of an alternating current (AC). 6. An electrodynamometer is an adaptation of the galvanometer, used to measure alternating currents. 6 7. Meters that depend on the heating effect of an electric current are used to measure alternating current of high frequency. II.3. MATCHING INFORMATION. Match the words on the left with their synonyms on the right: Εικόνα 2: Match the words on the left with their synonyms on the right. Source: Writer (2015). II.4. VOCABULARY EXPANSION. Each of the following words has several meanings. After reading the text decide with which meaning the word is used in your text. Tick the correct answer. Εικόνα 3: Exercise with vocabulary expansion. Source: Writer (2015). 7 5. PART III. INFORMATION TRANSFER – MATCHING Match the physical quantities with the units used to measure them. Εικόνα 4: Information transfer. Source: Writer (2015). 6. PART IV. PRACTISING GRAMMATICAL STRUCTURES III.1. Link the sentences below, making the second sentence in each pair a relative clause. Use relative pronouns, such as, who, which, where, whose. 1. Manganin is a metal. This metal has a comparatively high resistance. 2. Armoured cables are used in places. There is a risk of mechanical damage in these places. 3. Workers require illumination of 300 lux. The workers assemble heavy machinery. 4. The coil is connected in series with a resistor. The resistor has a value of 240 ohms. 8 5. Yesterday I saw the power engineer. His office is next to mine. 6. The supply is fed to a distribution substation. The supply is reduced to 415 V in the distribution substation. IV.2. Choose the correct answer. 1. What's the name of the machine tool ………….. you ordered last week? A. who B. where C. Which 2. The job ………… he got wasn't very interesting. A. that B. who C. when 3. He had a simple idea ………… changed the world. A. who B. which C. whose 4. Have you got anything …………………… replace that software? A. that can replace B. can replace C. who can replace 5. Here is the scheduling project ………………….. A. you asked me to get you. B. where you asked me to get you. C. what you asked me to get you. 6. This is Tom Potter, ………………… the plant. A. that runs B. who runs C. that he runs 7. Engineers are people ………… design and manufacture machines and tools. A. which B. who they C. who 8. is this the place ……………… you worked in for the first time? A. which B. in where C. where 9. I gave him my tools, …………………. were new and automatic . A. which B. that C. whose 10.They employed a man …………… experience was longer. A. who B. who his C. whose IV.3. Fill in the gaps with who, which, where, why and when and write the verbs in brackets in the correct tense. 9 Sam Potter, ……….. is 40 years old, is an electrical engineer in a Power Plant. 1978 ………… ( be) the year …………… he ………… (get) his first job. He ……………. (work) in the assembly line of a small company in Leeds, in …………… there were only 60 people. Sam …………. (love) his job and that's the reason …………. he ………….. (not / mind) getting up very early in the morning and getting back late in the afternoon. At weekends ……….. he …………….(not / work) he usually ………….. (go) on short journeys in the country. IV.4. Fill in the letter using the missing information below. Εικόνα 5: Grammatical structures exercise. Source: Writer (2015). 7. Glossary Πίνακας 1: Glossary. Source: Writer (2015). 10 GLOSSARY accuracy ακρίβεια adaptation προσαρμογή/διασκευή adjacent γειτονικός/παρακείμενος/συνεχόμενος alternation εναλλαγή/περιτροπή/αλληλοδιαδοχή ammeter αμπερόμετρο amperage ποσό ηλεκτρικού ρεύματος σε amp. ascertain εξακριβώνω attach επισυνάπτω/προσκολλώ/προσαρτώ beam of light δέσμη φωτός bypass παράκαμψη/παρακαμπτήριος/ διακλάδωση/βοηθητικός αγωγός calibrate διαμετρώ calibrated διαμετρημένος conduct οδηγώ/διευθύνω/διεξάγω/ συμπεριφέρομαι/είμαι αγωγός constant αδιάκοπος/συνεχής/σταθερός defined καθορισμένος deflect εκτρέπω –ομαι /αποκλίνω deflection απόκλιση devise επινοώ/μηχανεύομαι diathermy treatment θεραπεία με διαθερμίες disease ασθένεια electrical unit μονάδα ηλεκτρισμού electrodynamometer ηλεκτροδυναμόμετρο equivalent ισόδυναμος/ισότιμος/αντίστοιχος essentially βασικά/κατά βάση exhibit εκθέτω/επιδεικνύω fixed σταθερός/καθορισμένος/κανονισμένος/ αμετάβλητος/πάγιος/μόνιμος fixed coil σταθερό πηνίο friction τριβή indicate δείχνω/υποδεικνύω/υποδηλώνω 11 GLOSSARY inertia αδράνεια instant στιγμιαίος instrument όργανο magnitude μέγεθος measure μετρώ microammeter μικροαμπερόμετρο mirror καθρέπτης/κάτοπτρο movable κινητός moving κινητήριος/κινητικός/κινητός oscillating μεταβαλλόμενος/ταλαντευόμενος permanent μόνιμος/διαρκής/σταθερός pivoted περιστρεφόμενος pointer δείκτης/δείκτης θέσης principally κυρίως/προ παντός/ως επί το πλείστον proportionality αναλογικότητα reading ανάγνωση/ερμηνεία reflect αντανακλώ/απεικονίζω/δείχνω scale σκάλα/κλίμακα/ζυγαριά/κλιμακώνω shunt διακλάδωση/παράκαμψη/παράλληλος/ παραλληλισμός/παρακαμπτήρια γραμμή standard κανονικός/τυπικός/τυποποιημένος/ καθιερωμένος stretch εκτείνω/απλώνω/ανοίγω/τεντώνω/ επεκτείνω thermocouple θερμοζεύκτης treatment θεραπεία/μεταχείριση/επεξεργασία unlimited απεριόριστος vane πτερύγιο ανεμιστήρα/ πτερυγωτός/ ανεμοδείκτης/ανεμοδούρι 8. Βιβλιογραφία Ταβουλτζίδου, Σ. (n.d.). Ορολογία για Ηλεκτρολόγους Μηχανικούς. 12 9. Παράρτημα Σημείο αναφοράς. Copyright ΤΕΙ Δυτικής Μακεδονίας, Σταυρούλα Ταβουλτζίδου. «ΑΓΓΛΙΚΑ ΙΙΙ». Κοζάνη 2015. Έκδοση: 1.0. Κοζάνη 2015. Σημείωμα Αδειοδότησης. Το παρόν υλικό διατίθεται με τους όρους της άδειας χρήσης Creative Commons Αναφορά, Μη Εμπορική Χρήση Παρόμοια Διανομή 4.0 [1] ή μεταγενέστερη, Διεθνής Έκδοση. Εξαιρούνται τα αυτοτελή έργα τρίτων π.χ. φωτογραφίες, διαγράμματα κ.λ.π., τα οποία εμπεριέχονται σε αυτό και τα οποία αναφέρονται μαζί με τους όρους χρήσης τους στο «Σημείωμα Χρήσης Έργων Τρίτων». [1] http://creativecommons.org/licenses/by-nc-sa/4.0/ Ως Μη Εμπορική ορίζεται η χρήση: που δεν περιλαμβάνει άμεσο ή έμμεσο οικονομικό όφελος από την χρήση του έργου, για το διανομέα του έργου και αδειοδόχο. που δεν περιλαμβάνει οικονομική συναλλαγή ως προϋπόθεση για τη χρήση ή πρόσβαση στο έργο. που δεν προσπορίζει στο διανομέα του έργου και αδειοδόχο έμμεσο οικονομικό όφελος (π.χ. διαφημίσεις) από την προβολή του έργου σε διαδικτυακό τόπο. Ο δικαιούχος μπορεί να παρέχει στον αδειοδόχο ξεχωριστή άδεια να χρησιμοποιεί το έργο για εμπορική χρήση, εφόσον αυτό του ζητηθεί. Διατήρηση Σημειωμάτων. Οποιαδήποτε αναπαραγωγή ή διασκευή του υλικού θα πρέπει να συμπεριλαμβάνει: το Σημείωμα Αναφοράς. το Σημείωμα Αδειοδότησης. τη δήλωση Διατήρησης Σημειωμάτων. το Σημείωμα Χρήσης Έργων Τρίτων (εφόσον υπάρχει). μαζί με τους συνοδευόμενους υπερσυνδέσμους. Σημείωμα Χρήσης Έργων Τρίτων. Το Έργο αυτό κάνει χρήση των ακόλουθων έργων: Εικόνες/Σχήματα/Διαγράμματα/Φωτογραφίες. 13 "Battery," Microsoft (R) Encarta. Copyright (c) 1998 Microsoft Corporation. Copyright (c) 1998 Funk & Wagnall's Corporation. 14