
- Electrical Machines - Home
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- DC Machines
- Construction of DC Machines
- Types of DC Machines
- Working Principle of DC Generator
- EMF Equation of DC Generator
- Derivation of EMF Equation DC Generator
- Types of DC Generators
- Working Principle of DC Motor
- Back EMF in DC Motor
- Types of DC Motors
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- DC Generator
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- Stepper vs DC Motors
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- DC Machines Commutation
- DC Motor Characteristics
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- DC Generator Characteristics
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- DC Motor Voltage & Power Equations
- DC Generator Efficiency
- Electric Breaking of DC Motors
- DC Motor Efficiency
- Four Quadrant Operation of DC Motors
- Open Circuit Characteristics of DC Generators
- Voltage Build-Up in Self-Excited DC Generators
- Types of Armature Winding in DC Machines
- Torque in DC Motors
- Swinburne’s Test of DC Machine
- Speed Control of DC Shunt Motor
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- DC Motor of Speed Regulation
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- Permanent Magnet DC Motor
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- DC Series vs Shunt Motor
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- Induction Motors
- Introduction to Induction Motor
- Single-Phase Induction Motor
- 3-Phase Induction Motor
- Construction of 3-Phase Induction Motor
- 3-Phase Induction Motor on Load
- Characteristics of 3-Phase Induction Motor
- Speed Regulation and Speed Control
- Methods of Starting 3-Phase Induction Motors
- More on Induction Motors
- 3-Phase Induction Motor Working Principle
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- Determining Induction Motor Efficiency
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- 3-Phase Induction Motor Fault Types
- Synchronous Machines
- Introduction to 3-Phase Synchronous Machines
- Construction of Synchronous Machine
- Working of 3-Phase Alternator
- Armature Reaction in Synchronous Machines
- Output Power of 3-Phase Alternator
- Losses and Efficiency of an Alternator
- Losses and Efficiency of 3-Phase Alternator
- Working of 3-Phase Synchronous Motor
- Equivalent Circuit and Power Factor of Synchronous Motor
- Power Developed by Synchronous Motor
- More on Synchronous Machines
- AC Motor Types
- Induction Generator (Asynchronous Generator)
- Synchronous Speed Slip of 3-Phase Induction Motor
- Armature Reaction in Alternator at Leading Power Factor
- Armature Reaction in Alternator at Lagging Power Factor
- Stationary Armature vs Rotating Field Alternator Advantages
- Synchronous Impedance Method for Voltage Regulation
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- Significance of Short Circuit Ratio in Alternator
- Hunting Effect Alternator
- Hydrogen Cooling in Synchronous Generators
- Excitation System of Synchronous Machine
- Equivalent Circuit Phasor Diagram of Synchronous Generator
- EMF Equation of Synchronous Generator
- Cooling Methods for Synchronous Generators
- Assumptions in Synchronous Impedance Method
- Armature Reaction at Unity Power Factor
- Voltage Regulation of Alternator
- Synchronous Generator with Infinite Bus Operation
- Zero Power Factor of Synchronous Generator
- Short Circuit Ratio Calculation of Synchronous Machines
- Speed-Frequency Relationship in Alternator
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- Max Reactive Power in Synchronous Generators
- Power Flow Equations for Synchronous Generator
- Potier Triangle for Voltage Regulation in Alternators
- Parallel Operation of Alternators
- Load Sharing in Parallel Alternators
- Slip Test on Synchronous Machine
- Constant Flux Linkage Theorem
- Blondel's Two Reaction Theory
- Synchronous Machine Oscillations
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- Salient Pole Synchronous Machine Theory
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- Power-Angle of Salient Pole Machines
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- Power Input of Synchronous Generator
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- Hunting Synchronous Motor
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- V Curves & Inverted V Curves of Synchronous Motor
- Torque in Synchronous Motor
- Construction of 3-Phase Synchronous Motor
- Synchronous Motor
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- Power Flow in Synchronous Motor
- Types of Faults in Alternator
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- Electrical Generator
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- Solid State Motor Starters
- Characteristics of Single-Phase Motor
- Types of AC Generators
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- Electrical Machines Basic Terms
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- Stator and Rotor in Electrical Machines
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- Discussion
Four Quadrant Operation of DC Motor
A DC motor operates in two modes motoring and breaking.
- In motoring operation, it converts electrical energy into the mechanical energy, which assists its motion.
- In breaking operation, it converts mechanical energy into electrical energy, thus works as a generator and opposes its motion.
The motor can provide motoring and breaking operations in both forward and reverse directions. Therefore, a DC motor can operate in both directions of rotation and of producing both motoring and breaking, hence it is known as four quadrant operation of DC motor.
The power developed by the motor is given by the product of angular speed and the torque. If the developed power by motor is positive, then the mode of operation is called motoring and when the developed power is negative, the mode of operation is called breaking.
For the four quadrant operation of the motor, the sign conventions about the signs of speed and torque are given as follows −
- The speed of the motor is considered positive, when it is rotating in forward direction.
- In motor drives involving up and down motions, the speed of the motor in upward direction is considered to be forward motion.
- The torque is considered positive, when it produces acceleration.
- The torque is assigned negative sign, if it produces retardation.
Four Quadrant Operation
The four quadrant operation of the motor can be described as follows −
Quadrant I
In the first quadrant, the developed power by the motor is positive, thus the motor operates in motoring mode and converts electrical energy into mechanical energy. Therefore, the operation of the motor in first quadrant is called forward motoring.
Quadrant II
In the second quadrant, the direction of the rotation is positive i.e. speed is positive and the torque is negative. Hence, the developed power is negative and the machine operates as a generator which opposes its motion. The kinetic energy of the moving parts of the machines is converted into electrical energy. Therefore, the operation of motor in second quadrant is called forward breaking.
Quadrant III
In the third quadrant, the motor speed and torque both are negative, hence the power is positive. Therefore, the operation of the motor in the third quadrant is known as reverse motoring.
Quadrant IV
In the fourth quadrant, the motor speed is negative and the developed torque is positive, hence the motor power is negative which is corresponding to the breaking operation. Therefore, the operating in fourth quadrant is known as reverse breaking.
The four quadrant operation of the motor can be summarised in the figure shown below.
