# Recent questions and answers in Basic electrical and electronics engineering

Compare star and Delta Connection.

Write the relation between phase and line current, phase and line voltage for Star connection.

What is basic SI units?

State the working principle of transformer.

Why Transformer rating is given in kVA?

Classify the transformers based on the construction, frequency and power.

State any four advantages of three phase over single phase.

Define kVA rating of transformer.

Define: 1) voltage ratio, 2) current ratio, 3) transformation ratio of transformer.

1.Determine the permeability of magnetic material by plotting its BH curve 2. Measure voltage, current and power in 1-phase circuit with resistive load. 3. Measure voltage, current and power in R-L series circuit. 4.Determine the transformation ratio (K) of 1-phase transformer. 5.Connect single phase transformer and measure input and output quantities. 6.Make Star and Delta connection in induction motor starters and measure the line and phase values.

Draw the waveform of three phase AC supply voltage.

What is transformation ratio?

Define phase sequence of three phase supply with waveforms. What is normal phase sequence? Which 3 standard colours are used to denote the phase sequence?

Define transformer.

State any four applications of transformer.

State any four applications of three phase circuits.

State the four major parts of Transformer and material used for their construction.

For a balanced three phase star connected load for which line voltage is 230V and per phase resistance and reactance is 6 Ohm and 8 Ohm respectively. Calculate: 1) phase voltage 2) line current 3) power factor 4) total power absorbed

A balanced Delta connected load supplied with 440 V 50 Hz three phase AC supply has R=10 Ohm and L=0.6 mH in is each arm. Calculate line and phase current, active power.

A balanced three phase Delta connected load consists of three resistances each of four ohm's connected to a 400 V 3 phase 50 Hz supply. Find 1) phase voltage, 2) phase current, 3) line current, 4) power consumed.

A balanced three phase star connected load is supplied from a three phase 400V 50 Hz supply. The resistance for per phase is 10 Ohm. Find the value of phase current, line current, power factor and total power consumed.

Draw the phasor diagram for Star connected balanced system.