Category Archive for: «Low Voltage»

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Electrical Design Project Of a Small Bakery (1)

Electrical System of Bakery A small bakery with just a counter and storage areas is simple to design. The electrical design follows the layout for a house, but care must be taken on loading factors if direct-acting electric heaters are switched on all day. These days, many shops and stores have specialised equipment for cooking food or providing other […]

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Things About MCBs That Every Low Voltage Electrician Should Know

MCB Operation and characteristics An MCB is a thermo-magnetic device, meaning that it has two methods of circuit interruption. A thermal mechanism, usually a bi-metallic strip, provides protection against moderate overcurrent. The heating action of the current causes the bi-metallic strip to curve and break circuit contact. This method is complemented by a solenoid designed to respond to […]

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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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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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3 Lighting Essentials You Can’t Deny

Light Control / Energy Savings Lighting systems in industrial facilities can represent an attractive savings opportunity, especially if lighting systems have not been upgraded or maintained in the past five years. The most cost-effective approach for lighting energy savings is to address the following three issues, in order: Turn off lights during times when they are not […]

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4 Low Voltage Switchboard Partitioning Forms Defined By IEC 61439-2

Reasons for partitioning // There are 4 main reasons for partitioning a switchboard. To protect persons against direct contact with dangerous parts. The minimum degree of protection must be IPXXB. To protect the switchboard against the penetration of solid foreign bodies. The minimum degree of protection must be IP2X. To limit the propagation of an electric arc inside the switchboard […]

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Degradation of Insulation in Switchgear (What’s Really Happening)

Partial Discharge (PD) Electrical insulation is subjected to electrical and mechanical stress, elevated temperature and temperature variations, and environmental conditions especially for outdoor applications. In addition to normal operating conditions, there are a host of other factors that may trigger accelerated aging or deterioration of insulation. Both normal and accelerated aging of insulation produce the […]

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Inspection, Test and Measurement Procedures for LV and MV (up to 36kV) Switchgears

Importance of checks and maintenance Installed in clean, well ventilated or air-conditioned locations, switchgear will require little routine maintenance. Major inspection should be scheduled for power plant shutdowns and concentrate for low voltage switchboards on identifying contact wear, correct operation of interlocks, correct overload settings and fuse sizes, signs of overheating, and undue dirt or corrosion. For MV […]

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Electrical life (durability) of LV circuit breakers due to the switching operations

Test requirements According to the standard IEC 947-2, there is actually no defined stipulation regarding the requirements of electrical life of a circuit breaker. The numbers of switching operations which a circuit breaker under no-load, normal load, overload and short-circuit conditions has to make and/or break are stipulated. These numbers vary between two switchings (O-t-CO) […]

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7 Practical Tips For Installing a Good Measuring System

1. Start from the need: what do I want to measure? A single electric parameter or all the electric parameters There are different product families on the market: instruments that measure a single electric parameter (voltage, current, frequency, phase angle cosϕ), generally used in single phase systems, as instrumentation on the machine, and instruments that enable all the […]

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