Electrical installation handbook protection control and

Moulded-case circuit-breaker A circuit-breaker having a supporting housing of moulded insulating material forming an integral part of the circuit-breaker.

Withdrawable circuit breaker A circuit-breaker which, in addition to its interrupting contacts, has a set of isolating contacts which enable the circuit-breaker to be disconnected from the main circuit, in the withdrawn position, to achieve an isolating distance in accordance with specified requirements.

Electrical Installation Guide

Rated breaking capacity The rated breaking of an equipment is a value of current, stated by the manufacturer, which the equipment can satisfactorily break, under specified breaking conditions.

Disconnector A mechanical switching device which, in the open position, complies with the requirements specified for the isolating function. Electrical durability The electrical durability of an apparatus is expressed by the number of on-load operating cycles and gives the contact resistance to electrical wear under the service conditions stated in the relevant product Standard.

Release A device, mechanically connected to a mechanical switching device, which releases the holding means and permits the opening or the closing of the switching device.

The dimensioning of an electrical plant requires knowledge of different factors relating to, for example, installation utilities, the electrical conductors and other components; this knowledge leads the design engineer to consult numerous documents and technical catalogues.

In no case the maximum value of the rated operational voltage shall exceed that of the rated insulation voltage. Rated performances Voltages and frequencies Rated operational voltage Ue A rated operational voltage of an equipment is a value of voltage which, combined with a rated operational current, determines the application of the equipment and to which the relevant tests and the utilization categories are referred to.

ABB Protection and control devices 31 1. After the opening and closing sequence the circuit-breaker is not required to carry its rated current.

Rated insulation voltage Ui The rated insulation voltage of an equipment is the value of voltage to which dielectric tests voltage and creepage distances are referred. After this sequence the circuit-breaker is required to carry its rated current.

Main characteristics Circuit-breaker A mechanical switching device, capable of making, carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time and breaking currents under specified abnormal circuit conditions such as those of short-circuit.

Rated frequency The supply frequency for which an equipment is designed and to which the other characteristic values correspond. Performances under short-circuit conditions 32 Protection and control devices ABB 1. Rated short-time withstand current Icw The rated short-time withstand current is the current that the circuit-breaker in the closed position can carry during a specified short time under prescribed conditions of use and behaviour; the circuit-breaker shall be able to carry this current during the associated short-time delay in order to ensure discrimination between the circuit-breakers in series.

In order to perform this function, after detection of an anomalous condition, the release intervenes in a definite time by opening the interrupting part. This electrical installation handbook, however, aims to supply, in a single document, tables for the quick definition of the main parameters of the components of an electrical plant and for the selection of the protection devices for a wide range of installations.

Release A device, mechanically connected to a mechanical switching device, which releases the holding means and permits the opening or the closing of the switching device.

Current-limiting circuit breaker A circuit-breaker with a break-time short enough to prevent the short-circuit current reaching its otherwise attainable peak value. Plug-in circuit breaker A circuit-breaker which, in addition to its interrupting contacts, has a set of contacts which enable the circuit-breaker to be removed.

Compliance with the international Standard IEC Rated short-time withstand current Icw; i. Plug-in circuit-breaker A circuit-breaker which, in addition to its interrupting contacts, has a set of contacts which enable the circuit-breaker to be removed.

Such circuit-breakers have a short-time withstand current rating. Rated service short-circuit breaking capacity Ics The rated service short-circuit breaking capacity of a circuit-breaker is the maximum short-circuit current value which the circuit-breaker can break three times in accordance with a sequence of opening and closing operations O - t - CO - t — CO at a defined rated operational voltage Ue and at a defined power factor.

Rated short-circuit making capacity Icm The rated short-circuit making capacity of an equipment is the value of shortcircuit making capacity assigned to that equipment by the manufacturer for the rated operational voltage, at rated frequency, and at a specified power-factor for ac.The Electrical Installation Guide is written for electrical professionals who must design, install, inspect, and maintain low-voltage electrical installations in compliance with the standards published by the International Electrotechnical Commission (IEC).

Electrical installation handbook users The electrical installation handbook is a tool which is suitable for all those who are interested in electrical plants: useful for installers and maintenance technicians through brief yet important electrotechnical references, and for sales engineers through quick reference selection tables.

This electrical installation handbook, however, aims to supply, in a single document, tables for the quick definition of the main parameters of the components of an electrical plant and for the selection of the protection devices for a wide range of installations.

Protection and control devices. The main definitions regarding LV switchgear and. Electrical installation guide.

Electrical installation handbook Protection, control and

Pages. Electrical installation handbook Protection, control and electrical devices. The electrical installation handbook is a tool which is suitable for all those who are interested in electrical plants: useful for installers and maintenance technicians through brief yet important electrotechnical references, and for sales engineers through quick reference selection tables.

Protection and control devices Protection and control devices Electrical installation handbook Volume 1 1SDCD ABB SACE .

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Electrical installation handbook protection control and
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