Electrical and Control Systems

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Category: Power Systems

  • Types of Insulators used in Power Systems

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    John Mulindi
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    We have various types of overhead line and substation insulators. Generally they can be classified as: Post Insulators The post insulators comprise of pedestal posts and solid core cylindrical types. Pedestal post insulators The pedestal post insulator stacks employed in substations are available as single units with a range of lighting impulses withstand ratings (LIW)…

  • How Ground Fault Interrupter (GFI) is used as a Safety Device

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    John Mulindi
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    The function of a ground fault interrupter (GFI) is to disconnect the power if a current leakage to ground is detected. GFI is also termed to as Ground fault circuit interrupter (GFCI). We have two types of ground fault interrupters: those designed for life protection and those designed for equipment protection. GFI used for life…

  • Single-phase and Three-phase Power Systems

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    John Mulindi
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    Single-phase Power System To help us understand single-phase power system, consider the sine wave shown in figure 1(a) below of a 120 Vac single-phase power connected to a plug. We know very well that, voltage is the difference in potential between two points. Therefore the sine wave in figure 1(a) shows only the voltage difference…

  • Surge Suppression in Power Systems

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    John Mulindi
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    Causes of Power Surges Transient overvoltages in power systems may arise from a number of sources. Power disturbances resulting from lightning strikes or switching operations on transmission and distribution lines. The switching of power factor correction capacitors for voltage control is the main cause of switching transients. All utility lines are designed to certain basic…

  • Switchgear Equipment

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    John Mulindi
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    Switchgear can be defined as equipment used for controlling, regulating and switching ON and OFF power circuits. Switchgear units range from the small moulded-case unit circuit breakers in a household panel board to the huge, air break switches on 750 kV transmission lines. Switchgear equipment is generally divided into four groups, namely: Disconnect/Isolator Switches Disconnect…

  • Step by Step Guide: How to Check and Test a Power Transformer

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    John Mulindi
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    Testing of power transformers is continuous monitoring of faults in all units of such equipment and their timely removal after detection. All this is achieved with one objective continuation of the continuous activity of a significant node in the power supply system of many energy consumers. A variety of tests are used to determine the…

  • Single-phase vs. Three-phase Power Systems

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    John Mulindi
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    Thomas A. Edison’s work on electric light led to the concept of a centrally located power station with distributed electric power for lighting. Edison’s work on dc systems expanded with the development of three-wire 220 V dc systems but transmission distances and loads continued to grow, voltage problems were encountered but with the development of…