Power System

In a series RLC circuit, what is the nature of the power factor of the circuit if the frequency is very high

• unity

• leading

• lagging

• cannot be determined

Which of the following is not a unit of electrical energy?

• W

• Ws

• J

• kWh

What does a positive power in an electrical element indicate?

• Element may absorb or supply powe

• The sign of the power does not matter

• The element is supplying power

• The element is absorbing power

In three phase system, the three voltages (or currents) differ in phase by ____ electrical degrees from each other in a particular sequence.

• 30

• 120

• 60

• 90

Which of the following elements of electrical engineering cannot be analyzed using Ohm’s law?

• capacitors

• resistors

• inductors

• transistors

______ states that the total electric flux through any closed surface is equal to the charge enclosed by that surface.

• Faraday's law

• Gauss' law

• Lenz's law

• Maxwell's law

What part of an electric machine will the temperature rise mainly affect?

• speed of the machine

• conductance of the windings

• insulation of the machine

• output voltage of the machine

Transformer ratings are always given in:

• VA

• VAR

• W

• HP

An ideal transformer will have maximum efficiency at a load when ______.

• Pcu=Pco

• Pcu>Pco

• Pcu<Pco

• cannot be determined

For a star connected three phase AC circuit:

• None of these

• Line voltage is square root three times phase voltage and phase current is equal to line current

• Phase voltage is equal to line voltage and phase current is three times the line current

• Phase and line voltages and currents are equal