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Worksheetspower system protection
Total questions: 20
Worksheet time: 9mins
which of these are symmetrical fault
L-G
L-L-G
L-L
L-L-L
The component which provides a signal to circuit breaker under the fault condition:
Isolator
Fuse
Relay
CT
The correct statement about Buchholz relay
It can only be used with largely sized alternators
It is installed with largely sized transformers which have no conservator tank
It can detect incipient faults
It should never be used with oil immersed transformers
Buchholz relay is used to protect:
ALTERNATOR
INDUCTION MOTOR
SYNCHRONOUS MOTOR
TRANSFORMER
____________________ is/are an instantaneous relay/s:
PMMC type
Shaded pole type
Both of these
None of these
Plug setting multiplier is defined as the ratio of:
Fault current in relay coil x Pick up current
Fault current in relay coil / Pick up current
Fault current in relay coil x Transformer secondary turns
Fault current in relay coil / Transformer secondary turns
High-speed circuit breakers result in:
Increased stability of power systems
decreased stability of power systems
The basic purpose of a relay is to:
Detect the fault
Remove the fault
Trip the circuit
All of these
In Electrical power protection schemes ______________ transformer is used:
VT
CAPACITIVE VOLTAGE TRANFORMER
Both of these
None of these
The equipment which has lowest chances of fault occurrence:
Alternator
Transformer
Switchgear
Induction motors
A definite time relay is ___________ the amount of current:
Dependent on
Independent of
The extent of damage and injuries caused due to a shock depends on:
Amount of current
Path of the current
Time for which current flows
All of these
Backup protection is installed to:
Increase the protection reliability of the system
To increase the speed of protection system
Both of these
None of these
The hysteresis losses do not depend on
Volume of material
Magnetic field
Frequency
Either of them
None of these
Which of the following statement is true?
The magnetic field inside the conductor is zero
The magnetic field inside the semiconductor is zero
The magnetic field inside superconductor is zero
When any material has negative magnetism, the material is called as
Paramagnetic
Diamagnetic
Ferromagnetic
Antiferromagnetic
Which of the following materials are diamagnetic?
copper
silver
gold
iron
The current transformer can also be used to measured high d.c. current.
true
false
A voltage source can be converted into constant current source by adding
Low resistance in parallel with the voltage source
High resistance in parallel with the voltage source
Low resistance in series with the voltage source
High resistance in series with the voltage source
permeability in the magnetic circuit is analogous to
Resistance in electrical circuit
Resistivity in electrical circuit
Conductivity in electrical circuit
Current density
None of the above
