Switchgear protections

[amp_mcq option1=”power” option2=”current” option3=”voltage wave” option4=”all of the above” correct=”option1″]

Detailed SolutionDirectional relays are based on flow of

[amp_mcq option1=”heavy loads” option2=”internal short-circuits” option3=”external short-circuits” option4=”all of the above” correct=”option4″]

Detailed SolutionThe inverse definite mean time relays are used for over current and earth fault protection of transformer against

[amp_mcq option1=”slow making and breaking of load circuit contacts” option2=”foreign matter on the contact surface” option3=”too low contact pressure” option4=”all of the above” correct=”option4″]

Detailed SolutionOverheating of relay contacts or contact born out is due to

[amp_mcq option1=”mechanical vibration” option2=”insulation failure” option3=”loose connection” option4=”impulse voltage” correct=”option2″]

Detailed SolutionThe short circuit in any winding of the transformer is the result of

[amp_mcq option1=”zero sequence currents only” option2=”positive sequence currents only” option3=”negative and zero sequence currents” option4=”zero, negative and positive sequence currents” correct=”option4″]

Detailed SolutionA balanced 3-phase system consists of

[amp_mcq option1=”current during abnormal condition” option2=”voltage during abnormal condition” option3=”constantly the electrical quantities which differ during normal and abnormal conditions” option4=”none of the above” correct=”option3″]

Detailed SolutionProtective relays are devices that detect abnormal conditions in electrical circuits by measuring

[amp_mcq option1=”Oil circuit breakers” option2=”Air blast circuit breakers” option3=”Minimum oil circuit breakers” option4=”All of the above” correct=”option4″]

Detailed SolutionOn which of the following routine tests are conducted ?

[amp_mcq option1=”Inductance” option2=”Capacitance” option3=”Resistance” option4=”Reactance” correct=”option3″]

Detailed SolutionWhich of the following parameter can be neglected for a short line?

[amp_mcq option1=”interception” option2=”interception and conduction” option3=”interception, conduction and dissipation” option4=”interception, conduction, dissipation and reflection E. none of the above” correct=”option3″]

Detailed SolutionFor the protection of power station buildings against direct strokes the requirements are

[amp_mcq option1=”constant for all distances” option2=”lower than that of if fault occurs away from the relay” option3=”higher than that of if fault occurs away from the relay” option4=”none of the above” correct=”option3″]

Detailed SolutionIf the fault occurs near the impedance relay, the VII ratio will be