Switch Disconnector: Function, Applications, Benefits

Switch-disconnector combines the functions of a switch with the establishment of a disconnector and is used for breaking load currents up to their rated normal current. It makes and breaks under load conditions and provides safety isolation for any low-voltage circuit, particularly for machine control circuits.

It is normally operated manually and cannot interrupt the current on its own. It is only suitable for all-pole switching on and off and has no protective function. However, it is a condition that a separate protective device should be connected upstream of the systems.

The switch disconnector ensures the safety of the people and the equipment. It supports the users in creating a safe working environment, reducing the risk of electrical and mechanical accidents, especially during maintenance and repair work. It is suitable for diverse applications such as machinery, power distribution, switchboards, motor control centers, or photovoltaic installations. It is capable of closing
onto an existing short-circuit within the limits of its rated capacity with no risk to the operator or the equipment.

The switch-disconnector can be used as an emergency-off device. Therefore, it must be easily visible, accessible, and identifiable for easy identification. It uses special colors stipulated by the standards.

The switch disconnector must be chosen according to

• The characteristics of the network on which it is installed.
• The location and the application.
• Coordination with the upstream protection devices. (in particular overload and short-circuit)

Switch disconnectors are suitable for isolation. By using the handle on the front, the load and power can be disconnected. The mechanical design of switch disconnectors ensures the position of the handle always reflects the position of the main contacts:

• The isolation position corresponds to the O (OFF) position.
• The operating handle cannot indicate the OFF position unless the contacts are actually open.
• Padlocking in the OFF position is not possible unless the contacts are actually open.

Why switch disconnector is used?

The switch disconnector is used for maintenance and switching purposes as:

• Local isolation switch
• Main switch
• Control switch
• Fireman switch

It is used in many smaller machines and systems as well as portable devices, but also in larger rated current ranges. A switch disconnector is a device comprising movable contacts capable of being mechanically closed to form an electrical circuit to other equipment or of being mechanically opened to physically disconnect one part of the electrical network from an adjacent part and at the same time provide an isolating distance. This provides circuit segregation for operational purposes or, with appropriate earthing equipment and application of safety procedures, provides facilities to allow work to be safely undertaken on disconnected and earthed primary electrical equipment.

Advantages of switch disconnectors

The followings are the advantages of switch disconnectors:

• High safety and reliability.
• Top performance.
• Minimal maintenance.
• Easy installation and commissioning.
• Rotary, front and lateral, direct, and extended handle options.
• Durability to electromagnetic or mechanical vibrations.
• A high degree of protection.
• Cheap price.
• High breaking and making capacity.
• Suitable for diverse applications.
• Can also be mounted in positions other than the vertical (standard) position.
• Multiple accessories suiting application requirements enhance the flexibility of operation and safety level of installation.
• Disconnectors are generally hand-operated but may have power operating mechanisms if remote operational facilities
  are required.

Switch disconnector applications

Buildings

• Residential
• Healthcare
• Education
• Commercial offices
• Retail
• Public sector
• Airports

Information Technology

• Data centers
• Telecommunications
• Networks
• Computer rooms

Industrial & Machinery

• Manufacturing
• Agriculture
• Construction
• Mining and metals
• Processing
• Petrochemicals
• Pharmaceuticals
• Pulp and paper
• Material handling

Energy & Utilities

• Solar
• Wind
• Hydropower
• Oil
• Gas
• Smart grid
• Water and wastewater