AC Machinery Fundamentals

Summary:

1.  A simple loop in a uniform magnetic field

-          The voltage induced in a simple rotating loop

-          The Torque induced in a current-carrying loop

2.  The Rotating Magnetic Field

-          Proof of the rotating magnetic field concept

-          The relationship between Electrical Frequency and the Speed of Magnetic field rotation

-          Reversing the direction of magnetic field rotation

3.  Magnetomotive Force and Flux Distribution on AC Machines

4.  Induced Voltage in AC Machines

-          The induced voltage in a coil on a two-pole stator

-          The induced voltage in a three-phase set of coils

-          The RMS voltage in a Three-Phase Stator

 5.  Induced Torque in an AC Machines

See detail : AC Machinery Fundamentals

Overhead Line Design and Transmission Line Construction

The fundamental purpose of a Transmission or Distribution Line is to carry the active power from one point to another.

A Transmission line should possess the following characteristics:

• The voltage should be kept as constant as possible over the entire length of the line.
• The line losses must be small so as to obtain a high transmission efficiency
• The Copper losses must not overheat the conductor.

Components of a High Voltage Transmission Line

1. Conductors

• Conductors are always bare
• They are the vital link in the transmission system and distribution system
• They must be designed to meet the specified voltage level
• The conductor consideration should include the voltage level at which the power is transmitted, the maximum allowable losses on the line, the maximum thermal capacity of the line, the current carrying capacity and the tension of the line
• Factors which affect the location of the line include the climate of the country, the atmospheric conditions and vibration of the line

See detail : Overhead Line Design and Transmission Line Construction

Overview of Insulation Coordination

What is Insulation Coordination?

Insulation Coordination is the process of determining the proper insulation levels of various components in a power system as well as their arrangements. It is the selection of an insulation structure that will withstand voltage stresses to which the system, or equipment will be subjected to, together with the proper surge arrester. The process is determined from the known characteristics of voltage surges and the characteristics of surge arresters.

Some common terms that must be known when performing an Insulation Coordination Study.

1. Basic Impulse Insulation Level (BIL)

This is the reference insulation level expressed as an impulse crest (or peak) voltage with a standard wave not longer than a 1.2 x 50 microsecond wave.

A 1.2 x 50 microsecond wave means that the impulse takes 1.2 microseconds to reach the peak and then decays to 50% of the peak in 50 microseconds. (Below for a figure of the BIL waveform)

See detail : Overview of Insulation Coordination

Substation Design and Layout

The First Step in designing a Substation is to design an Earthing and Bonding System.

Earthing and Bonding

The function of an earthing and bonding system is to provide an earthing system connection to which transformer neutrals or earthing impedances may be connected in order to pass the maximum fault current. The earthing system also ensures that no thermal or mechanical damage occurs on the equipment within the substation, thereby resulting in safety to operation and maintenance personnel. The earthing system also guarantees eqipotential bonding such that there are no dangerous potential gradients developed in the substation.

In designing the substation, three voltage have to be considered.

1. Touch Voltage: This is the difference in potential between the surface potential and the potential at an earthed equipment whilst a man is standing and touching the earthed structure.

2. Step Voltage: This is the potential difference developed when a man bridges a distance of 1m with his feet while not touching any other earthed equipment.

3. Mesh Voltage: This is the maximum touch voltage that is developed in the mesh of the earthing grid.

See detail : Substation Design and Layout

National Electrical Code 2005 Handbook

Book Description:
Produced by the NFPA, the popular National Electrical Code® 2005 Handbook contains the complete text of the 2005 edition of the NEC® supplemented by helpful facts and figures, full-color illustrations, real-world examples and expert commentary. An essential reference for students and professionals, this Handbook is the equivalent of an annotated edition of the 2005 NEC® that offers insights into new and more difficult articles in order to guide users to success in interpreting and applying current Code requirements to all types of electrical installations. A valuable information resource for anyone involved in electrical design, installation and inspection, the NEC® 2005 Handbook is updated every three years and provides 100% of the information needed to “meet Code” and avoid costly errors. Thomson Delmar Learning is pleased to make this one-of-a-kind reference - containing the most widely accepted and most frequently used criteria for electrical installations in the U.S. - available directly from us for our customers who work in and around the electrical trades.

Electric Power Plant Design   

This manual provides engineering data and criteria for designing electric power plants where the size and characteristics of the electric power load and the economics of the particular facilit y justify on-site generation. Maximum size of plant considered in this manual is 30,000 kW. 

GENERAL
Purpose
Scope
References
Standards and Codes
Power Supply Design Criteria
Electrical Power Sytems
Design Procedures
Evaluation and Selection of Energy Systems
Design Analysis
Service Conditions
Explanation of Abbreviations and Terms

See detail :  Electrical Power Supply & Distribution