### Delta Star Transformation mcqs in network theorem electrical engineering

The delta-star transformation is used to convert a:

a) Delta-connected circuit to a star-connected circuit

b) Star-connected circuit to a delta-connected circuit

c) Series circuit to a parallel circuit

d) Parallel circuit to a series circuit

Answer: a) Delta-connected circuit to a star-connected circuit

Explanation: The delta-star transformation is used to convert a delta-connected circuit to a star-connected circuit.

The delta-star transformation is commonly applied in:

a) Power transmission systems

b) Lighting circuits

c) Digital logic circuits

d) Audio amplifiers

Answer: a) Power transmission systems

Explanation: The delta-star transformation is commonly applied in power transmission systems to convert between delta and star configurations.

The number of elements in a delta-connected circuit is:

a) Three

b) Four

c) Six

d) Nine

Answer: a) Three

Explanation: A delta-connected circuit consists of three elements connected in a triangular configuration.

The number of elements in a star-connected circuit is:

a) Three

b) Four

c) Six

d) Nine

Answer: b) Four

Explanation: A star-connected circuit consists of four elements connected in a star configuration.

The delta-star transformation is based on the principle of:

a) Kirchhoff’s Laws

b) Ohm’s Law

c) Thevenin’s Theorem

d) Norton’s Theorem

Answer: c) Thevenin’s Theorem

Explanation: The delta-star transformation is based on Thevenin’s Theorem, which states that any linear electrical network can be replaced by an equivalent circuit with a single voltage source and a single impedance.

In the delta-star transformation, the resistors in the delta configuration are replaced by:

a) Capacitors in the star configuration

b) Inductors in the star configuration

c) Resistors in the star configuration

d) None of the above

Answer: c) Resistors in the star configuration

Explanation: In the delta-star transformation, the resistors in the delta configuration are replaced by resistors in the star configuration.

The delta-star transformation is applicable to:

a) Resistive circuits only

b) Capacitive circuits only

c) Inductive circuits only

d) Circuits with any combination of resistive, capacitive, and inductive elements

Answer: d) Circuits with any combination of resistive, capacitive, and inductive elements

Explanation: The delta-star transformation can be applied to circuits containing resistive, capacitive, and inductive elements or combinations thereof.

The delta-star transformation is reversible, meaning:

a) A star-connected circuit can be converted to a delta-connected circuit

b) A delta-connected circuit can be converted to a star-connected circuit

c) Both a) and b)

d) None of the above

Answer: c) Both a) and b)

Explanation: The delta-star transformation is reversible, meaning a star-connected circuit can be converted to a delta-connected circuit and vice versa.

In the delta-star transformation, the impedance values in the delta configuration are related to the impedance values in the star configuration by a:

a) Multiplication factor of 1/√3

b) Multiplication factor of √3

c) Division factor of 1/3

d) Division factor of 3

Answer: b) Multiplication factor of √3

Explanation: In the delta-star transformation, the impedance values in the delta configuration are related to the impedance values in the star configuration by a multiplication factor of √3.

The delta-star transformation is particularly useful for simplifying calculations in circuits with:

a) Balanced loads

b) Unbalanced loads

c) High power ratings

d) Low power ratings

Answer: a) Balanced loads

Explanation: The delta-star transformation is particularly useful for simplifying calculations in circuits with balanced loads, where the impedance values are equal in magnitude and phase.

The delta-star transformation does not change the overall:

a) Power factor of the circuit

b) Power dissipation of the circuit

c) Voltage of the circuit

d) Current of the circuit

Answer: a) Power factor of the circuit

Explanation: The delta-star transformation does not change the overall power factor of the circuit. The power factor remains the same before and after the transformation.

In the delta-star transformation, the current in the delta configuration is related to the current in the star configuration by a:

a) Multiplication factor of 1/√3

b) Multiplication factor of √3

c) Division factor of 1/3

d) Division factor of 3

Answer: a) Multiplication factor of 1/√3

Explanation: In the delta-star transformation, the current in the delta configuration is related to the current in the star configuration by a multiplication factor of 1/√3.

The delta-star transformation is most commonly used in:

a) Three-phase power systems

b) Single-phase power systems

c) Digital communication systems

d) Audio systems

Answer: a) Three-phase power systems

Explanation: The delta-star transformation is commonly used in three-phase power systems to convert between delta and star configurations.

The delta-star transformation can be used to simplify calculations of:

a) Voltage drops

b) Current flows

c) Power losses

d) All of the above

Answer: d) All of the above

Explanation: The delta-star transformation can be used to simplify calculations of voltage drops, current flows, and power losses in a circuit.

The delta-star transformation is based on the concept of:

a) Series-parallel equivalence

b) Current division

c) Voltage division

d) Impedance matching

Answer: a) Series-parallel equivalence

Explanation: The delta-star transformation is based on the concept of series-parallel equivalence, where equivalent resistances are obtained by rearranging resistors in different configurations.

The delta-star transformation preserves the:

a) Power in the circuit

b) Voltage in the circuit

c) Current in the circuit

d) Resistance in the circuit

Answer: c) Current in the circuit

Explanation: The delta-star transformation preserves the current in the circuit. The total current remains the same before and after the transformation.

The delta-star transformation is not applicable when the circuit contains:

a) Only resistors

b) Only capacitors

c) Only inductors

d) None of the above

Answer: d) None of the above

Explanation: The delta-star transformation can be applied to circuits containing resistors, capacitors, inductors, or any combination thereof.

The delta-star transformation is useful for calculating the equivalent resistance of a:

a) Parallel circuit

b) Series circuit

c) Combination of series and parallel circuits

d) None of the above

Answer: c) Combination of series and parallel circuits

Explanation: The delta-star transformation is useful for calculating the equivalent resistance of a combination of series and parallel circuits.

The delta-star transformation is based on the assumption that the circuit is:

a) Operating at resonance

b) Operating in steady-state

c) Only resistive

d) Only capacitive

Answer: b) Operating in steady-state

Explanation: The delta-star transformation is based on the assumption that the circuit is operating in steady-state conditions, where voltages and currents are constant.

The delta-star transformation is particularly beneficial for analyzing circuits with:

a) High voltage levels

b) High current levels

c) Both high voltage and current levels

d) Low voltage and current levels

Answer: a) High voltage levels

Explanation: The delta-star transformation is particularly beneficial for analyzing circuits with high voltage levels, as it simplifies calculations and reduces complexity.