Essays on Stator

Three phase induction motors

Introduction The three-phase induction machine is the most widely used among the rotating machines. An induction machine offers an almost constant speed within its normal operating range when operated off a constant-voltage, constant-frequency, and with the electric power source. The cost of purchasing these machines is very low, and they require little maintenance. However, speed control is difficult and very expensive. Therefore, the rotor current of the three phase induction motors is not induced by electrical connections, but rather the rotation of magnetic field.

Squirrel Cage Rotor construction

The rotor type of the motor is made up of a laminated core which is ...

Introduction

Energy is a key driver of any nation’s economy. The extent to which it contributes to the performance of all activities surrounding the human life is beyond measure. This is because energy contributes almost fully to the economic development of the economy. In its physical form, energy is classified either as renewable or non-renewable. Renewable energy forms the green energy that can be reused again and is less toxic to the environment. On the other hand, non-renewable energy is exploited once it’s used and mostly pollutes the environment. All this energy forms can be either used directly ...

Abstract

This paper analyzes the importance of generator synchronization to the power grid, the required conditions to perform this procedure and the consequences of imprecise synchronization. For a generator to be synchronized to a grid, the voltage magnitude, frequency, phase sequence and phase angle must match. Manual synchronization depends on an operator to modify generator voltage and frequency, confirm phase sequences of generator and grid, and monitor phase angle difference to timely initiate breaker closure. Automatic synchronizers perform all these function through a computerized system that consists of complex algorithms and control systems, and are categorized in phase lock type ...

Abstract

Permanent magnet synchronous motors (PMSM) are a type of motors that have permanent magnets mounted on the rotors instead of the rotor windings. This particular design gives the motor a few advantages over ordinary induction synchronous motors. The magnets attached to the rotor do not require excitation, which reduces the power consumption in PMSM. This gives the motor high operational efficiency and reduces the motor active diameter. PMSM are therefore associated with applications that require high torque but have limited operation space. The permanent magnets suffer from flux leakage and are therefore aligned in a pattern that minimizes flux ...

Introduction

The fundamental process of thermal power plants is based on the conversion of thermal energy into mechanical energy and, subsequently, into electric power, using steam as the working fluid. According to the U.S. Energy Information System, over 67% of the electrical energy in the United States is generated through thermoelectric power plants, which use the combustion of fossil fuels such as natural gas, coal and petroleum to generate the steam necessary for the process; moreover, thermoelectric power generation accounts for an approximate 80% of all the power generation worldwide. Thus, the electricity consumed in most homes and industries is ...