Unit V: DC Motor Overview

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What type of energy does a DC Motor convert into mechanical energy?

Kinetic energy

Electrical energy (correct)

Sound energy

Light energy

What component of a DC Motor interacts with the magnetic field of the stationary magnet to apply a torque on the armature?

Yoke

Commutator

Armature coil (correct)

Field coil

In a large DC motor, what is used instead of permanent magnets to create the stator's magnetic field?

Yoke

Carbon brushes

Field coil (correct)

Commutator

Which component of a DC motor serves as the device's solid outer frame?

Stator Signup and view all the answers

What is the primary function of the yoke in a DC motor?

Provide structural strength Signup and view all the answers

What is the purpose of a pole shoe in a DC motor?

To produce a magnetic field when excited by the field coil Signup and view all the answers

What is the material usually used for the armature core in a DC motor?

Silicon steel Signup and view all the answers

What is the function of carbon brushes in a DC motor?

Conduct electricity to the armature coils Signup and view all the answers

Why are DC series motors advantageous for high starting loads?

They have few turns of larger wire capable of carrying full load current Signup and view all the answers

How is speed affected in a DC series motor as the load changes?

Speed increases Signup and view all the answers

What is the speed equation of a DC series motor?

N = Eb/f Signup and view all the answers

What happens to the speed versus armature current curve up to magnetic saturation in a DC series motor?

It forms a hyperbola Signup and view all the answers

What is the main principle a transformer operates on?

Mutual induction principle Signup and view all the answers

What are the main materials used for constructing the core of a transformer?

Silicon steel and cold-rolled grain-oriented steel Signup and view all the answers

Which part of a single-phase transformer is used as both a coolant and an insulating medium?

Transformer oil Signup and view all the answers

What is the main difference between a DC Shunt motor and a DC Compound motor?

The way the field winding is connected Signup and view all the answers

What happens to the speed of a DC Shunt motor when the load is increased?

It decreases slightly Signup and view all the answers

At what point does the rotor require a very large current to start a heavy load in a DC Shunt motor?

When the load increases Signup and view all the answers

What does the torque vs. armature current curve look like for a DC Series motor before magnetic saturation?

Parabola Signup and view all the answers

In a DC Compound motor, what is the function of the series winding compared to the shunt field?

Provides higher starting torque Signup and view all the answers

What is the main purpose of Buchholz relay in a single-phase transformer?

To protect against internal and early faults Signup and view all the answers

What happens to the color of silica gel crystals after excessive usage?

They turn pale pink Signup and view all the answers

What purpose do bushings serve in a transformer?

To determine HV and LV windings Signup and view all the answers

What is the main function of tap changer in a single-phase transformer?

To balance voltage changes Signup and view all the answers

In a single-phase transformer, what happens when it is operating at no load?

Current in secondary winding is zero Signup and view all the answers

What is the primary counter-balancing current called?

I'1 Signup and view all the answers

What does the total primary current I1 represent in the transformer equation?

Vector sum of no-load current and additional current Signup and view all the answers

What is the formula for form factor in the context of induced emf?

RMS Value / Average Value Signup and view all the answers

What are the losses that occur in an actual transformer?

Copper losses Signup and view all the answers

What causes hysteresis loss in a transformer?

Continuous reversal of molecular magnets Signup and view all the answers

What is the reason for using silicon steel material for the core of a transformer?

To minimize hysteresis loss Signup and view all the answers

How can eddy current loss in a transformer be minimized?

By making the core of thin laminations Signup and view all the answers

What induces an emf in the core of a transformer?

Eddy currents Signup and view all the answers

Which losses in a transformer are independent of the load?

Iron loss Signup and view all the answers

What material can be used to construct the core of a transformer to minimize hysteresis loss?

Silicon steel Signup and view all the answers

How do copper losses vary in a transformer?

Copper losses vary with load Signup and view all the answers

What can be done to minimize eddy current loss in a transformer?

Change the type of winding wire Signup and view all the answers

Why do copper losses occur in a transformer?

Due to ohmic resistance Signup and view all the answers

What is the primary reason for the dissipation of power in a transformer?

Eddy current loss Signup and view all the answers

How does the use of thin laminations help in reducing losses in a transformer?

Minimizes eddy current loss Signup and view all the answers

What component of a DC Motor interacts with the magnetic field of the stationary magnet to apply a torque on the armature?

Commutator Signup and view all the answers

Which component of a DC motor acts as the frame for providing structural strength to the motor?

Yoke Signup and view all the answers

What is the primary function of the stator in a DC motor?

Serve as the stationary component Signup and view all the answers

In large DC motors, what is used instead of permanent magnets to create the stator's magnetic field?

Field coil Signup and view all the answers

What is the rotary component inside a DC motor's casing, surrounded by strong permanent magnets?

Armature coil Signup and view all the answers

What type of material is the armature core usually made of in a DC motor?

Laminated wrought iron Signup and view all the answers

What is the primary function of the commutator in a DC motor?

Converts torque from alternating to unidirectional on the armature Signup and view all the answers

What is the role of the field winding in a DC motor?

To generate a magnetic field when a direct current is passed through it Signup and view all the answers

What is the main purpose of the pole shoe in relation to the armature?

Maximize the magnetic flux passing to the armature Signup and view all the answers

What kind of motor winding configuration allows the speed of the motor to be dependent on the load?

Series winding Signup and view all the answers

What happens to the speed of a DC Shunt motor with an increase in load?

Decreases slightly Signup and view all the answers

What is the main difference between the torque versus armature current curve for a DC Shunt motor and a DC Series motor?

Parabola for DC Shunt, straight line for DC Series Signup and view all the answers

In a DC Compound motor, what effect does allocating more space to the series winding have on the speed with load?

Decreases speed with load Signup and view all the answers

What feature allows a DC Compound motor to provide a combination of shunt and series motor characteristics?

Connect armature in series with field turns Signup and view all the answers

Which characteristic establishes the DC Shunt motor as a constant flux machine?

Field winding directly across supply voltage Signup and view all the answers

What is the speed equation for a DC series motor?

N = Eb/f Signup and view all the answers

What happens to the speed versus armature current curve up to magnetic saturation in a DC series motor?

It is a hyperbola Signup and view all the answers

Which part of a single-phase transformer is mainly responsible for providing a low reluctance path for magnetic flux flow?

Core Signup and view all the answers

In a DC motor, what is the primary function of bushings?

To insulate the windings Signup and view all the answers

How is the transformer oil typically used in single-phase transformers?

As a coolant and insulating medium Signup and view all the answers

What is the primary component of the no-load current in a transformer responsible for supplying iron losses?

Active or power component Signup and view all the answers

Which color do fresh silica gel crystals typically have, before turning pale pink due to excessive usage?

Blue Signup and view all the answers

What is the primary function of the explosion vent in a transformer?

Preventing transformer explosion Signup and view all the answers

What is the main objective of using tap changer in a single-phase transformer?

Balancing all the voltage changes Signup and view all the answers

Which parameter of the transformer determines the primary winding's current at no load condition?

Rated current Signup and view all the answers

What is the additional primary current I’1 used for in a transformer?

To induce the magnetomotive force N1I’1 Signup and view all the answers

What is the power factor angle ?1 of the primary side of the transformer based on?

The phase difference between the primary current I1 and voltage V1 Signup and view all the answers

What determines the power factor of the secondary side of a transformer?

The load connected to the transformer Signup and view all the answers

What is the main reason for the voltage regulation of a transformer?

Change in terminal voltage due to internal parameters Signup and view all the answers

What causes the core or iron losses in a transformer?

Hysteresis and eddy current losses Signup and view all the answers

What is the primary method to minimize hysteresis loss in a transformer?

Making the core from silicon steel material Signup and view all the answers

How can eddy current loss be reduced in a transformer?

Using thicker laminations for the core Signup and view all the answers

What is the main reason for the occurrence of copper losses in a transformer?

Ohmic resistance in the winding conductors Signup and view all the answers

How do iron losses in a transformer vary with respect to the load?

Remain constant irrespective of load variations Signup and view all the answers

What is the best way to minimize constant losses in a transformer?

Operating the transformer at a lower frequency Signup and view all the answers

What is the consequence of high ohmic resistance in the winding conductors of a transformer?

Higher copper losses Signup and view all the answers

How does using solid iron material for the core impact the eddy current losses in a transformer?

Increases eddy current losses Signup and view all the answers

In what scenario would the copper losses in a transformer be at their peak?

At full-load conditions Signup and view all the answers

What is the primary benefit of varying the load in a transformer?

To optimize power efficiency Signup and view all the answers

Why is operating a transformer at a higher frequency not a common practice to reduce losses?

It would increase hysteresis losses Signup and view all the answers

Unit V: DC Motor Overview

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Questions and Answers

What type of energy does a DC Motor convert into mechanical energy?

What component of a DC Motor interacts with the magnetic field of the stationary magnet to apply a torque on the armature?

In a large DC motor, what is used instead of permanent magnets to create the stator's magnetic field?

Which component of a DC motor serves as the device's solid outer frame?

What is the primary function of the yoke in a DC motor?

What is the purpose of a pole shoe in a DC motor?

What is the material usually used for the armature core in a DC motor?

What is the function of carbon brushes in a DC motor?

Why are DC series motors advantageous for high starting loads?

How is speed affected in a DC series motor as the load changes?

What is the speed equation of a DC series motor?

What happens to the speed versus armature current curve up to magnetic saturation in a DC series motor?

What is the main principle a transformer operates on?

What are the main materials used for constructing the core of a transformer?

Which part of a single-phase transformer is used as both a coolant and an insulating medium?

What is the main difference between a DC Shunt motor and a DC Compound motor?

What happens to the speed of a DC Shunt motor when the load is increased?

At what point does the rotor require a very large current to start a heavy load in a DC Shunt motor?

What does the torque vs. armature current curve look like for a DC Series motor before magnetic saturation?

In a DC Compound motor, what is the function of the series winding compared to the shunt field?

What is the main purpose of Buchholz relay in a single-phase transformer?

What happens to the color of silica gel crystals after excessive usage?

What purpose do bushings serve in a transformer?

What is the main function of tap changer in a single-phase transformer?

In a single-phase transformer, what happens when it is operating at no load?

What is the primary counter-balancing current called?

What does the total primary current I1 represent in the transformer equation?

What is the formula for form factor in the context of induced emf?

What are the losses that occur in an actual transformer?

What causes hysteresis loss in a transformer?

What is the reason for using silicon steel material for the core of a transformer?

How can eddy current loss in a transformer be minimized?

What induces an emf in the core of a transformer?

Which losses in a transformer are independent of the load?

What material can be used to construct the core of a transformer to minimize hysteresis loss?

How do copper losses vary in a transformer?

What can be done to minimize eddy current loss in a transformer?

Why do copper losses occur in a transformer?

What is the primary reason for the dissipation of power in a transformer?

How does the use of thin laminations help in reducing losses in a transformer?

What component of a DC Motor interacts with the magnetic field of the stationary magnet to apply a torque on the armature?

Which component of a DC motor acts as the frame for providing structural strength to the motor?

What is the primary function of the stator in a DC motor?

In large DC motors, what is used instead of permanent magnets to create the stator's magnetic field?

What is the rotary component inside a DC motor's casing, surrounded by strong permanent magnets?

What type of material is the armature core usually made of in a DC motor?

What is the primary function of the commutator in a DC motor?

What is the role of the field winding in a DC motor?

What is the main purpose of the pole shoe in relation to the armature?

What kind of motor winding configuration allows the speed of the motor to be dependent on the load?

What happens to the speed of a DC Shunt motor with an increase in load?

What is the main difference between the torque versus armature current curve for a DC Shunt motor and a DC Series motor?

In a DC Compound motor, what effect does allocating more space to the series winding have on the speed with load?

What feature allows a DC Compound motor to provide a combination of shunt and series motor characteristics?

Which characteristic establishes the DC Shunt motor as a constant flux machine?

What is the speed equation for a DC series motor?

What happens to the speed versus armature current curve up to magnetic saturation in a DC series motor?

Which part of a single-phase transformer is mainly responsible for providing a low reluctance path for magnetic flux flow?

In a DC motor, what is the primary function of bushings?

How is the transformer oil typically used in single-phase transformers?

What is the primary component of the no-load current in a transformer responsible for supplying iron losses?

Which color do fresh silica gel crystals typically have, before turning pale pink due to excessive usage?

What is the primary function of the explosion vent in a transformer?

What is the main objective of using tap changer in a single-phase transformer?

Which parameter of the transformer determines the primary winding's current at no load condition?

What is the additional primary current I’1 used for in a transformer?

What is the power factor angle ?1 of the primary side of the transformer based on?

What determines the power factor of the secondary side of a transformer?

What is the main reason for the voltage regulation of a transformer?

What causes the core or iron losses in a transformer?

What is the primary method to minimize hysteresis loss in a transformer?

How can eddy current loss be reduced in a transformer?

What is the main reason for the occurrence of copper losses in a transformer?

How do iron losses in a transformer vary with respect to the load?

What is the best way to minimize constant losses in a transformer?

What is the consequence of high ohmic resistance in the winding conductors of a transformer?