SUBJECTS
|
BROWSE
|
CAREER CENTER
|
POPULAR
|
JOIN
|
LOGIN
Business Skills
|
Soft Skills
|
Basic Literacy
|
Certifications
About
|
Help
|
Privacy
|
Terms
|
Email
Search
Test your basic knowledge |
Transformers
Start Test
Study First
Subject
:
engineering
Instructions:
Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can
study here
.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.
This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. A simple design has a core within each coil
Secondary
open-ended core
Primary
Autotransformer
2. The current related to turns ratio law
Ip Ns = Is Np
Eh - lH = Ex - lX
copper losses (I2R); hysteresis losses (lagging losses); and eddy current losses (swirling currents)
variable
3. A test instrument used to indicate low voltage potentials in the range of 110 to 600 volts either alternating or direct current. (slang term: wiggy)
Measuring
wigginton
by using silicon iron core
step-up (high voltage) transformers - step down transformer - autotransformer
4. The winding of a transformer to which electrical energy is supplied.
primary winding
Hysteresis - Eddy - Current
X1 - X2...
rating
5. To prevent injury to personnel when servicing any equipment connected to a current transformer - the secondary winding must be ____ - _____.
silicon steel
Voltage
Short Circuited: Unless the secondary winding is short-circuited - a high open circuit voltage that can be dangerous will exist.
Exciting Current
6. The winding to which the load is connected is called the _____ winding.
high frequency transformer
closed-ended core
Hysteresis - Eddy - Current
Secondary
7. The output rating of a transformer is based upon the maximum _____ the transformer is capable of carrying without exceeding a certain temperature rise.
polarity
Current
change the input voltage
Exciting
8. How coils serve as the primary and secondary windings for an autotransformer
Ip Ns = Is Np
phase
closed-ended core
one coils serves as the primary and secondary windings
9. The current flowing through the primary winding - in response to the applied primary voltage - sets this up
a magnetic field that varies quickly in direction and stregnth
How a transformer works
Measuring Equipment
Vs Ip = Vp Is
10. In a transformer the _____ current will always flow in such a direction that its magnetizing action will oppose the magnetizing action of the primary winding.
continuous path
Copper Losses - Core Losses
Secondary
Primary
11. For a step up and step down transformer if the turns ratio is constant this is the only way to change the output voltage
copper losses (I2R); hysteresis losses (lagging losses); and eddy current losses (swirling currents)
Exciting Current
change the input voltage
by varying the size of the applied DC
12. Kind of wire is the secondary coil in a transformer
Voltage
current related to voltage law
thin copper wire coated with insulated material (shellac or enamel)
class 400 transformers
13. The transformer winding to which the load is connected is called the _____ winding.
Kilovolt -- Amperes (kVA)
Choke coil
Transformer
Secondary
14. The relationship between current and voltage in the coils are inverse
current related to voltage law
Transformer
open-ended core
Secondary
15. An electromagnetic device that operates on the principle of self induction. It uses AC.
die to leakage flux
Choke coil
ammeter
Kilovolt -- Amperes (kVA)
16. A ___________ transformer is a continuously adjustable Autotransformer.
the number of turns in the coil
electromagnetic mutual induction without loosing too much energy
variable
primary winding
17. The total numbre of lines or force issuing from a pole. (north or south)
5
fault
Primary
magnetic flux
18. The formula for the current related to voltage law
Insulates - cools transformer by convection - dissipates heat
Vs Ip = Vp Is
rating
Exciting Current
19. Provides the ratio between the applied primary voltage and the induced secondary voltage as result of the turns ratio
one coils serves as the primary and secondary windings
Measuring Equipment
primary coil
voltage ralated to turns ratio
20. This core is more efficient than the air core because the iron core in each coil intensifies the magnetic flux in both primary and secondary coils when they become magnetized as current flows through each set of coils
open-ended core
flux
Hysteresis
short circuit
21. has a laminated iron core (layers of metal plates)
fuse
die to leakage flux
Hysteresis - Eddy - Current
closed-ended core
22. This type of core is moderately efficient due to closing the core and layering design which reduces power loss from less leakage flux which provides a continuous path for magnetic flux and an increase in field strength
ammeter
Aire core -open ended core -closed ended core (square/doughnut shaped) -shell core
closed-ended core
Eh/Ex=Th/Tx
23. Copper loss is known as _____ loss.
fuse
Primary
Secondary
24. Divergence of the magnetic field causes this
fuse
leakage flux
Low
air core
25. The terminals of the high voltage winding are marked _____.
wigginton
closed-ended core
H1 - h2...
dielectric oil
26. _____ shows that the voltages across the windings of a transformer are directly proportional to the turns in each winding.
Eh/Ex=Th/Tx
Ip Ns = Is Np
fuse
5
27. closed core with a top and bottom. It directs the magnetic field towards the primary and secondary coils and increases the field stregnth
Primary
eddy currents
closed-ended core (square/doughnut shaped)
Low
28. _____ currents are reduced by laminating the core.
closed-ended core (square/doughnut shaped)
a magnetic field that varies quickly in direction and stregnth
Eddy
ratio of a transformer
29. Used to increase the magnetic flux in a transformer
a magnetic field that varies quickly in direction and stregnth
fuse
central magnetic core
current related to voltage law
30. Current flows through the primary winding in response to primary voltage and sets up a magnetic field that varies in direction and stregnth. under the influence of the changing magnetic field an AC voltage/kv is induced across the secondary coil by e
How a transformer works
high frequency transformer
current related to voltage law
H1 - h2...
31. The 3 types of transformer power loss
closed-ended core
copper losses (I2R); hysteresis losses (lagging losses); and eddy current losses (swirling currents)
Primary
closed-ended core
32. The output which can be delivered for the time specified at rated secondary voltage and rated frequency without exceeding the specified temperature limitations.
magnetic flux
rated KVA of a transformer
fuse
33. Modern; used to control filament circuit; replaced both the rheostat and choke coil; operated on the electromagnetic principle that if an iron core within or near a coil is saturated with magnetic flux by an independed source of direct current - the
saturable reactor
Volt-Amperes (Eh-lh=ExLx)
transformers efficiency law
Primary
34. A part of a circuit made of a low melting point material so that it will melt and break the circuit when a specified current exceeded. Always the weakest point in the circuit.
fuse
Secondary
air core
Secondary
35. Transformers designed for 4800 volt primary operation - but the secondaries are connected 240/480 volts. Winding ratio is 10:1
Same
an iron core and coil
air core
class 400 transformers
36. A designated limit of operating characteristics based on definite conditions.
low rententivity
A small three-phase meter used to determine the direction of phase rotation on circuits or transformer banks.
flux
rating
37. A variable transformer is a continuously adjustable _____ - has the primary winding and secondary winding electrically connected.
ratio of a transformer
open-ended core
Exciting
Autotransformer
38. How a variable degree of core saturation is accomplished in a saturable reactor?
by varying the size of the applied DC
step-up (high voltage) transformers - step down transformer - autotransformer
leg(s)
Simple Transformer
39. It refers to the direction of current flow in a closed circuit.
a magnetic field that varies quickly in direction and stregnth
variable
polarity
die to leakage flux
40. ___________ is often used in laminated cores - increases electrical resistance which decreases eddy currents
grounded (Earthed)
closed-ended core (square/doughnut shaped)
by using silicon iron core
silicon steel
41. The turns of both windings are cut by the same flux; therefore the induced emf in each turn of both windings is the _____.
step-up (high voltage) transformers - step down transformer - autotransformer
Measuring Equipment
Measuring
Same
42. Hysteresis Loss can be reduced by using a core with this feature
low rententivity
wigginton
Simple Transformer
continuous path
43. The shape of the core of the transformer ensures a ______________ for the magnetic flux with maximum concentration within the core and minimum leakage of the air
Aire core -open ended core -closed ended core (square/doughnut shaped) -shell core
continuous path
Same
copper losses (I2R); hysteresis losses (lagging losses); and eddy current losses (swirling currents)
44. When an alternating current is applied to the high-voltage (H) winding of a transformer with no load on the secondary (X) winding - a small current - called the _____ current - flows in the primary.
Short Circuited: Unless the secondary winding is short-circuited - a high open circuit voltage that can be dangerous will exist.
Voltage
Exciting
a magnetic field that varies quickly in direction and stregnth
45. A transformer is a device that has no moving parts and that transfers energy from one circuit to another by _____.
Ip Ns = Is Np
magnetic flux
Electromagnetic Induction.
transformers efficiency
46. The volt-amperes of the primary of a transformer is equal to the _____ - _____ output of the transformer.
Volt-Amperes (Eh-lh=ExLx)
the number of turns in the coil
A small three-phase meter used to determine the direction of phase rotation on circuits or transformer banks.
X1 - X2...
47. Defined as the ratio of the power output to the power input (in a closed circuit containing resistance)
transformers efficiency law
class 400 transformers
wigginton
Choke coil
48. Reference to a jumper or conductor - to or from a piece of electrical equipment.
Copper Losses - Core Losses
fuse
Voltage
leg(s)
49. If the transformer is used as a _____ transformer - the low voltage winding is the primary.
leakage flux
Step-up
Exciting Current
A small three-phase meter used to determine the direction of phase rotation on circuits or transformer banks.
50. A transformer is a device that either increases or decreases alternating current and voltage using this principle
Eddy
closed-ended core
Secondary
electromagnetic mutual induction without loosing too much energy
Sorry!:) No result found.
Can you answer 50 questions in 15 minutes?
Let me suggest you:
Browse all subjects
Browse all tests
Most popular tests
Major Subjects
Tests & Exams
AP
CLEP
DSST
GRE
SAT
GMAT
Certifications
CISSP go to https://www.isc2.org/
PMP
ITIL
RHCE
MCTS
More...
IT Skills
Android Programming
Data Modeling
Objective C Programming
Basic Python Programming
Adobe Illustrator
More...
Business Skills
Advertising Techniques
Business Accounting Basics
Business Strategy
Human Resource Management
Marketing Basics
More...
Soft Skills
Body Language
People Skills
Public Speaking
Persuasion
Job Hunting And Resumes
More...
Vocabulary
GRE Vocab
SAT Vocab
TOEFL Essential Vocab
Basic English Words For All
Global Words You Should Know
Business English
More...
Languages
AP German Vocab
AP Latin Vocab
SAT Subject Test: French
Italian Survival
Norwegian Survival
More...
Engineering
Audio Engineering
Computer Science Engineering
Aerospace Engineering
Chemical Engineering
Structural Engineering
More...
Health Sciences
Basic Nursing Skills
Health Science Language Fundamentals
Veterinary Technology Medical Language
Cardiology
Clinical Surgery
More...
English
Grammar Fundamentals
Literary And Rhetorical Vocab
Elements Of Style Vocab
Introduction To English Major
Complete Advanced Sentences
Literature
Homonyms
More...
Math
Algebra Formulas
Basic Arithmetic: Measurements
Metric Conversions
Geometric Properties
Important Math Facts
Number Sense Vocab
Business Math
More...
Other Major Subjects
Science
Economics
History
Law
Performing-arts
Cooking
Logic & Reasoning
Trivia
Browse all subjects
Browse all tests
Most popular tests