POWER SYSTEM PROTECTION

Which of these are symmetrical fault

• L-L

• L-G

• L-L-G

• 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

High-speed circuit breakers result in:

• Increased stability of power systems

• decreased stability of power systems

The hysteresis losses do not depend on

• Volume of material

• Magnetic field

• Frequency

• Either of them

• None of these

The equipment which has lowest chances of fault occurrence:

• Alternator

• Transformer

• Switchgear

• Induction motors

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

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

The current transformer can also be used to measured high d.c. current.

• True

• False

Which of the following materials are diamagnetic?

• copper

• silver

• gold

• iron