Download Ενότητα 9: Electric Meters

ΑΓΓΛΙΚΑ ΙΙΙ
Ενότητα 9: Electric Meters: Measurement of Current
Σταυρούλα Ταβουλτζίδου
Τμήμα Ηλεκτρολόγων Μηχανικών ΤΕ
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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
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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.
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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
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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.
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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).
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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.
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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.
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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).
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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
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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.
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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.
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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:
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το Σημείωμα Αναφοράς.
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το Σημείωμα Αδειοδότησης.
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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.
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
"Battery," Microsoft (R) Encarta. Copyright (c) 1998 Microsoft Corporation.
Copyright (c) 1998 Funk & Wagnall's Corporation.
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