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. The loss of power required to reverse the core magnatism each time the current reverses. This loss is caused by friction between the molecules of iron as these particles are aligned first in one direction and the in the opposite direct as current dir
Primary
Hysteresis
high frequency transformer
ammeter
2. It refers to the direction of current flow in a closed circuit.
Primary
fault
Transformer
polarity
3. Copper loss is known as _____ loss.
Low
Volt-Amperes (Eh-lh=ExLx)
highly permeable material - iron or stalloy
4. Central magnetic core made of
Hysteresis
highly permeable material - iron or stalloy
change the input voltage
voltage ralated to turns ratio
5. An electromagnetic device that operates on the principle of self induction. It uses AC.
current related to turns ratio law
A small three-phase meter used to determine the direction of phase rotation on circuits or transformer banks.
Choke coil
an iron core and coil
6. The current related to turns ratio law
step-up (high voltage) transformers - step down transformer - autotransformer
grounded (Earthed)
open-ended core
Ip Ns = Is Np
7. A transformer rated at 500KVA and below used for voltage transformation on the distribuition system.
CORE: Core losses are caused by eddy currents set up by the magnetic field.
voltage ralated to turns ratio
Exciting Current
Distribution transformer
8. The formula for the voltage related to turns ratio
Copper Losses - Core Losses
rated KVA of a transformer
Vs Ns = Vp Np
9. The voltage induced in the coil is directly proportional to this
Low
air core
Distribution transformer
the number of turns in the coil
10. Two coils wound on a closed iron core form a ________.
The ratio of useful power output to its total power input.
primary coil - secondary coil - central magnetic core
Simple Transformer
low rententivity
11. The turns of both windings are cut by the same flux; therefore the induced emf in each turn of both windings is the _____.
Kilovolt -- Amperes (kVA)
central magnetic core
Secondary
Same
12. 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.
change the input voltage
by varying the size of the applied DC
rated KVA of a transformer
Secondary
13. How coils serve as the primary and secondary windings for an autotransformer
Choke coil
air core
variable transformers
one coils serves as the primary and secondary windings
14. This is the most advanced and most efficient type of tansformer; it is commonly used in x-ray equipment
shell core
Autotransformer
Electromagnetic Induction.
secondary coil
15. What is a rotation meter?
short circuit
Step-up
Transformer
A small three-phase meter used to determine the direction of phase rotation on circuits or transformer banks.
16. Hysteresis Loss can be reduced by using a core with this feature
shell core
low rententivity
Eddy
class 400 transformers
17. A magnetic field changing with respect to the conductor will generate a _____ in the conductor.
Short Circuited: Unless the secondary winding is short-circuited - a high open circuit voltage that can be dangerous will exist.
Secondary
closed-ended core
Voltage
18. A transformer is a device that has no moving parts and that transfers energy from one circuit to another by _____.
Electromagnetic Induction.
rated KVA of a transformer
High voltage
5
19. The magnetic lines of force that flow from the north pole of a magnet and return to the south pole.
transformers efficiency law
primary coil
flux
leakage flux
20. A variable transformer is a continuously adjustable _____ - has the primary winding and secondary winding electrically connected.
eddy currents
electromagnetic mutual induction without loosing too much energy
a magnetic field that varies quickly in direction and stregnth
Autotransformer
21. With no load on the secondary winding - a small current flows in the primary called _____ _____.
high frequency transformer
secondary coil
Electromagnet
Exciting Current
22. The turns ratio between the windings (primary & secondary) of a transformer unless otherwise specified.
Primary
ratio of a transformer
How a transformer works
central magnetic core
23. ___________ is often used in laminated cores - increases electrical resistance which decreases eddy currents
Vs Ip = Vp Is
short circuit
silicon steel
CORE: Core losses are caused by eddy currents set up by the magnetic field.
24. 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)
polarity
air core
wigginton
25. The transformer winding to which the load is connected is called the _____ winding.
Secondary
variable transformers
closed-ended core
copper losses (I2R); hysteresis losses (lagging losses); and eddy current losses (swirling currents)
26. Used to increase the magnetic flux in a transformer
Voltage - Current
Voltage
phase
central magnetic core
27. The relationship between current and voltage in the coils are inverse
open-ended core
the number of turns of wire in the primary and secondary coils
current related to voltage law
28. Transformers designed for 4800 volt primary operation - but the secondaries are connected 240/480 volts. Winding ratio is 10:1
class 400 transformers
CORE: Core losses are caused by eddy currents set up by the magnetic field.
Voltage - Current
Electromagnetic Induction.
29. The total numbre of lines or force issuing from a pole. (north or south)
open-ended core
magnetic flux
X1 - X2...
closed-ended core
30. has a laminated iron core (layers of metal plates)
ratio of a transformer
the number of turns in the coil
closed-ended core
high frequency transformer
31. The current flowing through the primary winding - in response to the applied primary voltage - sets this up
open-ended core
High voltage
a magnetic field that varies quickly in direction and stregnth
step-up (high voltage) transformers - step down transformer - autotransformer
32. Refers to the transformer's ability to avoid power loss (heat)
coercivity
magnetic flux
transformers efficiency
copper losses (I2R); hysteresis losses (lagging losses); and eddy current losses (swirling currents)
33. The relationship between amperage flowing through the coils and the number of turns on individual coils is inverse
X1 - X2...
Low
a magnetic field that varies quickly in direction and stregnth
current related to turns ratio law
34. The output rating of a transformer is based upon the maximum _____ the transformer is capable of carrying without exceeding a certain temperature rise.
secondary coil
Step-down
Current
X1 - X2...
35. A magnet made by winding a coil of wire around a soft iron core. Current passed through this winding produces magnetic lines of force in the coil.
current related to turns ratio law
Electromagnet
Copper Losses - Core Losses
Insulates - cools transformer by convection - dissipates heat
36. This type of transformer power loss is caused by the continually changing AC current movement which constantly magnetizes/demagnetizes/re-magnetizes
Secondary
5
Simple Transformer
hysteresis losses (lagging losses)
37. Divergence of the magnetic field causes this
leakage flux
Eh - lH = Ex - lX
a magnetic field that varies quickly in direction and stregnth
X1 - X2...
38. Defined as the ratio of the power output to the power input (in a closed circuit containing resistance)
constant current transfomers
central magnetic core
A small three-phase meter used to determine the direction of phase rotation on circuits or transformer banks.
transformers efficiency law
39. Core losses are _____ loss and _____ - _____ loss.
Short Circuited: Unless the secondary winding is short-circuited - a high open circuit voltage that can be dangerous will exist.
CORE: Core losses are caused by eddy currents set up by the magnetic field.
Current
Hysteresis - Eddy - Current
40. The 3 principle components of a transformer
voltage ralated to turns ratio
variable transformers
primary coil - secondary coil - central magnetic core
short circuit
41. The number of turns can be adjusted in these types of transformers
variable transformers
magnetic flux
open-ended core
Autotransformer
42. A transformer loses less than _% in energy
5
change the input voltage
Voltage - Current
wigginton
43. The winding to which voltage is supplied is called the _____ winding.
Primary
closed-ended core (square/doughnut shaped)
the number of turns of wire in the primary and secondary coils
H1 - h2...
44. The volt-amperes of the primary of a transformer is equal to the _____ - _____ output of the transformer.
magnetic flux
electromagnetic mutual induction without loosing too much energy
Volt-Amperes (Eh-lh=ExLx)
central magnetic core
45. How coercivity is minimized
by using silicon iron core
low rententivity
Electromagnetic Induction.
by varying the size of the applied DC
46. Both the primary and secondary coils in a transformer are arranged around this
Electromagnetic Induction.
shell core
central magnetic core
directly proportional
47. The entire transformer is placed in a metal tank then immersed in ________.
dielectric oil
a magnetic field that varies quickly in direction and stregnth
transformers efficiency
current related to turns ratio law
48. 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
Secondary
saturable reactor
Electromagnetic Induction.
49. If the transformer is used as a _____ transformer - the low voltage winding is the primary.
Step-up
Electromagnet
closed-ended core
Class 200 transformers
50. A partial or total local failure in the insulation or continuity of a conductor.
fault
step-up (high voltage) transformers - step down transformer - autotransformer
Eddy
eddy currents
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