The basic functions of LV switchgear: Difference between revisions

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{{Menu_LV_switchgear_functions_and_selection}}
{{Menu_LV_switchgear_functions_and_selection}}
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The role of switchgear is:  
'''Switchgear''': General term covering switching devices and their combination with associated control, measuring, protective and regulating equipment, also assemblies of such devices and equipment with associated interconnections, accessories, enclosures and supporting structures, intended in principle for use in connection with generation, transmission, distribution and conversion of electric energy [IEV 441-11-02]. }}
*Electrical protection
*Safe isolation from live parts
*Local or remote switching
 
}}


National and international standards define the manner in which electric circuits of LV installations must be realized, and the capabilities and limitations of the various switching devices which are collectively referred to as switchgear.
Low voltage electrical installation rules such as IEC 60364 series and related national standards give:
* rules for design and erection of electrical installation, and
* requirement for selection of electrical equipement including the devices to ensure protection and control of the electrical installation.
These devices are collectively referred to as «switchgear».


The main functions of switchgear are:
'''The main functions of switchgear are''':
*Electrical protection
* [[LV switchgear functions - Electrical protection|Electrical protection]]
*Electrical isolation of sections of an installation
* [[LV switchgear functions - Isolation|Electrical isolation of the electrical installation, circuits or individual equipment]]
*Local or remote switching
* [[LV switchgear functions - Switchgear control|Local or remote switching ]]


These functions are summarized below in {{FigureRef|H1}}.
These functions are summarized below in {{FigureRef|H1}}.
 
{{tb-start|id=Tab1260|num=H1|title=Basic functions of LV switchgear|cols=5}}
Electrical protection at low voltage is (apart from fuses) normally incorporated in circuit-breakers, in the form of thermal-magnetic devices and/or residual-currentoperated tripping devices (less-commonly, residual voltage- operated devices - acceptable to, but not recommended by IEC).
 
In addition to those functions shown in {{FigureRef|H1}}, other functions, namely:
*Over-voltage protection
*Under-voltage protection
are provided by specific devices (lightning and various other types of voltage-surge arrester, relays associated with contactors, remotely controlled circuit-breakers, and with combined circuit-breaker/isolators… and so on)
 
{| class="wikitable"
{| class="wikitable"
|-
|-
| '''Electrical protection against'''
! Electrical protection against
| '''Isolation'''
! Isolation  
| '''Control'''
! Control
|-
|-
|  
|  
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'''''Fig. H1:''' Basic functions of LV switchgear''
In addition to those functions shown in {{FigureRef|H1}}, other functions, namely:
 
*Over-voltage protection
 
*Under-voltage protection
{{Manual_TOC |
are provided by specific devices (lightning and various other types of voltage-surge arrester, relays associated with contactors, remotely controlled circuit-breakers, and with combined circuit-breaker/isolators… and so on)
* [[LV switchgear functions - Electrical protection]]
* [[LV switchgear functions - Isolation]]
* [[LV switchgear functions - Switchgear control]]
}}
 
[[ru:Основные функции низковольтной распределительной аппаратуры]]
[[zh:低压开关设备的基本功能]]

Latest revision as of 09:47, 22 June 2022

Switchgear: General term covering switching devices and their combination with associated control, measuring, protective and regulating equipment, also assemblies of such devices and equipment with associated interconnections, accessories, enclosures and supporting structures, intended in principle for use in connection with generation, transmission, distribution and conversion of electric energy [IEV 441-11-02].

Low voltage electrical installation rules such as IEC 60364 series and related national standards give:

  • rules for design and erection of electrical installation, and
  • requirement for selection of electrical equipement including the devices to ensure protection and control of the electrical installation.

These devices are collectively referred to as «switchgear».

The main functions of switchgear are:

These functions are summarized below in Figure H1.

Fig. H1 – Basic functions of LV switchgear
Electrical protection against Isolation Control
  • Overload currents
  • Short-circuit currents
  • Insulation failure
  • Isolation clearly indicated by an authorized fail-proof mechanical indicator
  • A gap or interposed insulating barrier between the open contacts, clearly visible
  • Functional switching
  • Emergency switching
  • Emergency stopping
  • Switching off for mechanical maintenance

In addition to those functions shown in Figure H1, other functions, namely:

  • Over-voltage protection
  • Under-voltage protection

are provided by specific devices (lightning and various other types of voltage-surge arrester, relays associated with contactors, remotely controlled circuit-breakers, and with combined circuit-breaker/isolators… and so on)

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