The process of connecting neutral point of 3-phase system to earth (i.e. soil) either directly or through some circuit element (e.g. resistance, reactance etc.) is called neutral grounding. Neutral grounding provides protection to personal and equipment. It is because during earth fault, the current path is completed through the earthed
Year: 2014
The conversion of energy available in different forms in nature into electrical energy is known as generation of electrical energy. Electrical energy is a manufactured commodity like clothing, furniture or tools. Just as the manufacture of a commodity involves the conversion of raw materials available in nature into the desired
Energy may be needed as heat, as light, as motive power etc. The present-day advancement in science and technology has made it possible to convert electrical energy into any desired form. This has given electrical energy a place of pride in the modern world. The survival of industrial undertakings and
The electric power system in India is 3-phase AC operating at a frequency of 50 Hz. The power station delivers power to consumers through its transmission and distribution systems. The power delivered must be characterized by constant or nearly constant voltage, dependability of service, balanced voltage, and efficiency so as
The variable load on a power station introduces many perplexities in its operation. Some of the important effects of variable load on a power station are (i) NEED OF ADDITIONAL EQUIPMENT: The variable load on a power station necessitates to have additional equipment. By way of illustration, consider a steam
In order to prevent or correct harmonic problems that could occur within an industrial facility, an evaluation of system harmonics should be performed if the facility conditions meet one or more of the criteria below. 1. The application of capacitor banks in systems where 20% or more of the load
The effects of three-phase harmonics on circuits are similar to the effects of stress and high blood pressure on the human body. High levels of stress or harmonic distortion can lead to problems for the utility’s distribution system, plant distribution system and any other equipment serviced by that distribution system.
Conventional electromagnetic devices as well as semiconductor applications act as sources of harmonics. Conventional electromagnetic devices include stationary transformer as well as rotating machines. Harmonic generation in these machine depends on the properties of the materials used to construct them, different design constraints and considerations, operating principle and of course
Rotating machines also act as source of harmonics in power system. Causes of harmonics generation in rotating electrical machines are classified into following categories: 1. MAGNETIC NONLINEARITIES OF THE CORE MATERIAL: Nonlinear magnetization characteristics of the core material cause harmonic generation. 2. NON UNIFORM FLUX DISTRIBUTION IN AIR GAP: often
Transformer magnetic material characteristic is nonlinear. This non linearity is the main reason for harmonics during excitation. Sources of harmonics in transformer may be classified into four categories as follows: 1. NORMAL EXCITATION: Normal excitation current of a transformer is non-sinusoidal. The distortion is mainly caused by zero sequence triplen
