## Voltage Transformer Earthing

Voltage Transformer Earthing: In this method of neutral earthing, the primary of a single-phase Voltage Transformer Earthing is connected between the neutral and the earth as shown in Fig. 26.17. A low resistor in series with a relay is connected across the secondary of the voltage transformer. The Voltage Transformer Earthing provides a high reactance […]

## Resonant Grounding

Resonant Grounding or Arc Suppression Coil Grounding: We have seen that capacitive currents are responsible for producing arcing grounds. These capaci­tive currents flow because capacitance exists between each line and earth. If inductance L of appro­priate value is connected in parallel with the capacitance of the system, the fault current IF flowing through L will be […]

## Resistance Grounding

Resistance Grounding: In order to limit the magnitude of earth fault current, it is a common practice to connect the neutral point of a 3-phase system to earth through a resistor. This is called Resistance Grounding. When the neutral point of a 3-phase system (e.g. 3-phase generator, 3-phase transformer etc.) is connected to earth (i.e. […]

## Solid Grounding

Solid Grounding or Effective Grounding: When the neutral point of a 3-phase system (e.g. 3-phase generator, 3-phase transformer etc.) is directly connected to earth (i.e. soil) through a wire of negligible resistance and reactance, it is called Solid Grounding or Effective Grounding. Fig. 26.11 shows the solid grounding of the neutral point. Since the neutral […]

## Neutral Grounding

Neutral Grounding: 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 neutral and the […]

## Ungrounded Neutral System

Ungrounded Neutral System: In an ungrounded neutral system, the neutral is not connected to the ground i.e. the neutral is isolated from the ground. Therefore, this system is also called isolated neutral system or free neutral system. Fig. 26.7 shows ungrounded neutral system. The line conductors have capacitances between one another and to ground. The […]

## System Grounding

System Grounding: The process of connecting some electrical part of the power system (e.g. neutral point of a star-connected system, one conductor of the secondary of a transformer etc.) to earth (i.e. soil) is called System Grounding. The system grounding has assumed considerable importance in the fast expanding power system. By adopting proper schemes of […]

## Grounding or Earthing

Grounding or Earthing: The process of connecting the metallic frame (i.e. non-current carrying part) of electrical equipment or some electrical part of the system (e.g. neutral point in a star-connected system, one conductor of the secondary of a transformer etc.) to earth (i.e. soil) is called Grounding or Earthing. It is strange but true that […]

## Key Diagram of Substation

Key Diagram of Substation 66/11KV: Fig. 25.10 shows the key diagram of a typical 66/11 kV sub-station. The Key Diagram of Substation can be explained as under: 1. There are two 66 kV incoming lines marked ‘incoming 1’ and ‘incoming 2’ connected to the bus-bars. Such an arrangement of two incoming lines is called a […]

## Busbar Arrangements in Substations

Busbar Arrangements in Substations: Busbar are the important components in a sub-station. There are several Busbar Arrangements in Substations that can be used in a sub-station. The choice of a particular arrangement depends upon various factors such as system voltage, position of sub-station, degree of reliability, cost etc. The following are the important bus-bar arrangements […]

## Equipments in Transformer Substation

Equipments in Transformer Substation: The Equipments in Transformer Substation depends upon the type of sub-station, service requirement and the degree of protection desired. However, in general, the Equipments in Transformer Substation are : 1. Bus-bars: When a number of lines operating at the same voltage have to be directly connected electrically, bus-bars are used as the […]

## Transformer Substation

Transformer Substation: The majority of the sub-stations in the power system are concerned with the changing of voltage level of electric supply. These are known as Transformer Substation because transformer is the main component employed to change the voltage level. Depending upon the purpose served, Transformer Substation may be classified into : Step-up sub-station Primary […]

## Substation

Substation: The assembly of apparatus used to change some characteristic (e.g. voltage, ac. to dc., frequency, p.f. etc.) of electric supply is called a Substation. Sub-stations are important part of power system. The continuity of supply depends to a considerable extent upon the successful operation of sub-stations. It is, therefore, essential to exercise utmost care […]

## Surge Absorber

Surge Absorber: The travelling waves set up on the transmission lines by the surges may reach the terminals apparatus and cause damage to it. The amount of damage caused not only depends upon the amplitude of the surge but also upon the steepness of its wave front. The steeper the wave front of the surge, […]

## Lightning Arresters

Lightning Arresters: The earthing screen and ground wires can well protect the electrical system against direct lightning strokes but they fail to provide protection against travelling waves which may reach the terminal apparatus. The Lightning Arresters or surge diverters provide protection against such surges. A lightning arresters or a surge diverter is a protective device […]

## Types of Lightning Strikes

Types of Lightning Strikes: There are two Types of Lightning Strikes may strike the power system (e.g. overhead lines, towers, sub-stations etc.), namely; Direct stroke Indirect stroke 1. Direct stroke: In the direct stroke, the lightning discharge (i.e. current path) is directly from the cloud to the subject equipment e.g. an overhead line. From the […]

## Lightning

Lightning: An electric discharge between cloud and earth, between clouds or between the charge centres of the same cloud is known as lightning. Lightning is a huge spark and takes place when clouds are charged to such a high potential (+ ve or – ve) with respect to earth or a neighbouring cloud that the […]