Category Archive for: «Energy and Power»

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13 Basic expressions often used in electrical testing

Testing of electrical installations // This is the simple list of basic terms you can often hear when testing and measurements of electrical installation (in general) is being performed. While expirienced electrical engineers will find this list short, I hope beginners will catch the essence and continue exploring this field of electrical engineering. Feel free […]

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Two Circuit-Breaker Types For Automatic Disconnection Of the Supply

Automatic disconnection The Standard IEC 60364 prescribes automatic disconnection of the supply for protection against indirect contact. What does it mean // The protective device shall automatically disconnect the supply so that, in the event of a fault between a live part and an exposed-conductive-part or a protective conductor, a prospective touch voltage exceeding 50 […]

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Comparision of Direct-on-line (DOL) and Star-delta Motor Starting

Motor starting methods // Direct-on-line (DOL) starting Advantages Drawbacks Star-delta starting Advantages Drawbacks Comparision of DOL and Star-delta starting Direct-on-line starting (DOL) As the name suggests, direct-on-line starting means that the motor is started by connecting it directly to the supply at rated voltage. Direct-on-line starting, (DOL), is suitable for stable supplies and mechanically stiff […]

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Differences in size and weight of equipment using copper and aluminium conductors

Common misconception It is a common misconception that electrical equipment built using aluminum conductors will always be larger than the same equipment using copper conductors. While the actual conductor within the equipment will be larger with aluminum, many times the enclosure for the equipment is the same size whether copper or aluminum conductors are used. […]

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MV Metal-Enclosed Switchgear and Loss of Service Continuity (LSC) Categories

Accessibility and service continuity Some parts of a switchgear may be made accessible for the user, for various reasons from operation to maintenance, and such an access could impair the overall operation of the switchgear then decreasing the availability. The IEC 62271-200 proposes user-oriented definitions and classifications intended to describe how a given switchgear can […]

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4 Main Means For The Generation Of Reactive Power

It’s all about reactive power… The four main means for the generation of reactive power are: Synchronous alternators Synchronous compensators (SC) Static var compensators (SVC) and Banks of static capacitors 1. Synchronous alternators Synchronous alternators are the main machines used for the generation of electrical energy. Besides, without going into technical details, by acting on […]

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Take Into Account the Losses When Purchasing Power Transformer

Transformer Price and Losses The Connection Losses and purchase price should be considered when deciding which transformer to purchase. The purpose of this technical article is to present a uniform approach that can be used to determine the dollar value of these losses over the life of the transformer. Below is typical wording of a transformer loss evaluation clause […]

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Example for Coordination of Cascaded Circuit Breakers

Inputs for Coordination Calculation A 440 V 60 Hz switchboard feeds a 4-wire distribution board for small loads such as socket outlets. The switchboard has a fault making capacity of 100kA rms. After applying diversity factors to the loads the total load current is 90 A. Moulded case circuit breakers (MCCBs) rated at 16 A […]

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Calculation of motor starting time as first approximation

Motor starting operations The problems connected to motor starting operations are fundamentally linked to the type of motor which a determined motor operational torque “CM” offers, to the starting modality and to the connected load which has a determined load torque “C ”. A generic curve of the above mentioned quantities is shown in the Figure […]

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5 Copper Busbar Jointing Methods

Efficient joints in copper busbar conductors Efficient joints in copper busbar conductors can be made very simply by: Bolting Clamping Riveting Soldering Welding Bolting and clamping are used extensively on-site. Shaped busbars may be prefabricated by using friction stir welding. 1. Bolted joints (most common) Bolted joints are formed by overlapping the bars and bolting […]

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