Electrical Switchgear
National and international standards define the method for making electrical distribution circuits as well as the purpose and functions of switchgear. There are three main functions, namely:
- Circuit protection takes three main fault types into account:
- Overloads,
- Short-circuits (Both of which adversely affect the lifetime of cables and loads)
- Insulation faults, harmful for persons and equipment.
- Isolation is used to separate a circuit or a device from the remainder of the installation to allow 100% safe operation,
- Control allows the user to take voluntary action on installation operation:
- When such action takes place in normal operating conditions (on load, with no overcurrent) in order to energise or de-energise all or part of the installation, control is said to be “functional”,
- When such action is essential (whatever the load condition of the installation) in order to immediately de-energise all or part of the installation, control is said to be of the “emergency stop” kind.
Three main functions of electrical circuits:
- Protection,
- Isolation,
- Control,
The switch is used for:
- Control,
- Often isolation.
For protection it must be combined with:
- Circuit-breaker,
- Fuses,
- Residual current device (if necessary).
A variety of switchgear perform all or some of these three main functions. The following table situates the role of the main switchgear:
| Functions perfomed Protections | Isolation | Control | |||
| Switchgear | Overloads | Short-circuit | Insulation-fault | ||
| Fuse | Yes (3) | Yes | No | No | No |
| Disconnector | No | No | No | Yes | No |
| Switch | No | No | Yes? (1)(2) | Yes? | Yes |
| Disconnector – fuse | Yes | Yes | No | Yes | No |
| Switch – fuse | Yes | Yes | Yes? (1)(2) | Yes? | Yes |
| Contactor | No | No | No | No | Yes |
| Circuit-breaker | Yes | Yes | Yes? (2) | Yes? | Yes |
Yes – Basic function of the switchgear considered (always performed)
Yes? – Additional function possible (not always performed)
(1) Possible with a switch with automatic opening.
(2) Possible with addition of a “Residual Current Device (RCD)“.
(3) gG fuse only
Resource // Schneider Electric – Low voltage switches
Related electrical guides & articles
Edvard Csanyi
Hi, I'm an electrical engineer, programmer and founder of EEP - Electrical Engineering Portal. I worked twelve years at Schneider Electric in the position of technical support for low- and medium-voltage projects and the design of busbar trunking systems.I'm highly specialized in the design of LV/MV switchgear and low-voltage, high-power busbar trunking (<6300A) in substations, commercial buildings and industry facilities. I'm also a professional in AutoCAD programming.
Profile: Edvard Csanyi
@Edvard Casanyi : it is very useful site adding a knowledge and experience
@Gurprme eet Singh : I would like to know more about CNC programming. could you give a reference about that ? Thanks a lot.
informative….very helpful
My name is Gurpreet Singh from Virdi enterprises , we are the sheet metal parts manufacturer in INDIA .
We specialize in custom metal fabrication projects for low or high volume, high quality production. Our facility is flexible equipped to handle prototype, short-run and long-run production work at competitive prices and best services.
We sincerely hope could be your reliable sheet metal parts supplier for your projects , looking forward to hearing from you, thanks.
Commonly Manufacturing Fields
· Custom fabricated sheet metal products
· Metal covers, Db boxes spn & tpn , tubes, and cabinets
· Metal panels
· Custom metal shelving and brackets
· Metal electronics components
· Vehicle components
· Lighting components
· Laser components
· Plastic components
· Cnc Plasma cutting components
· Electrical HT, LT / Drowout Panel Parts
Our Capabilities
· CNC Machining
· Stamping and Punching
· CNC Laser Cutting
· CNC/Automatic Lathe
· Fastener and Fitting Insertion
· Product Assembly
· Highly skilled sheet metal fabricators
· Coated, Plated, Anodized finishing
Materials Range
· Steel
· Stainless steel
· Aluminum
· Copper
· Brass
· FR ( Fire Resistant )
· Glass apoxy , bekalite etc.