Overcurrent - protection against

Fuses are used when it is possible to use a simple and economic method of protection against overcurrents and fanlts. They are fast to act when a major fault occurs and are very reliable. 

The consumer s mains equipment must provide protection against overcurrent, that is, a current exceeding the rated value (lET Regulation 430.3). Fuses provide overcurrent protection when situated in the live conductors they must not be connected in the neutral conductor. Circuit-breakers may be used in place of fuses, in which case the circuit-breaker may also provide the means of isolation, although a further means of isolation is usually provided so that maintenance can be carried out on the circuit-breakers themselves. 

The essential requirements for a device designed to protect against overcurrent are ... 

Selection and Erection Isolation and Switching Inspection and Testing Protection against Fire Protection against Electric Shock Protection against Overcurrent Special Locations Earthing and Bonding... 

Protection against Electric Shock. Protection against Overcurrent... 

You probably know that electrical circuits have devices to protect against overcurrents (too many amps for the circuit) or from a ground fault condition (where the circuit inadvertently connects to... 

Protection against overcurrent Constant temperature heating Electrical heater, curing iron... 

Protection against overcurrent and electric shock is in section 3. It compares the performances of semi-enclosed and cartridge fuses and MCBs for both overcurrent and short circuit protection. It deals with RCDs for earth leakage and electric shock protection. It concludes with Tables 10 and 11 for the sizes of main earthing, main bonding and supplementary bonding conductors. 

Protection against overcurrent and short circuit current is required and is mainly provided by circuit breakers fitted with overload trips. At the initial planning stage the supply company should be asked for the prospective fault level at the supply intake so that adequately rated equipment may be selected. At this position, if a switchfuse is used to control the installation and the BS 88 FIBC fuses specified in BS EN 60439-4 are employed, there should be no problem as the breaking capacity is not less than 80 k A at 400 V. If a moulded case circuit breaker is used, however, it is necessary to select one of adequate fault breaking capacity as they are made for a range of ratings. 

The consumer s mains equipment must provide protection against overcurrent that is, a current exceeding the rated value (lET Regulation 430.3). Fuses provide... 

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