New Electronics – Switch disconnectors

Switch disconnectors are commonly used critical components of electrical systems, allowing the disconnection of electrical equipment for maintenance or repair. In this article, we present the construction and operation of switch disconnectors, their basic functional characteristics and discuss how to find the right product for your application.

  • Switch disconnectors – principle of operation
  • How to choose the switch-disconnector?
  • Switch-disconnector – what to look for?

In an electrical installation, switch-disconnectors are electromechanical elements used to break the circuit. Installed in a distribution board, they often function as a main switch. Undoubtedly, it is one of the basic elements of current flow control systems, commonly used in distribution networks and switchboards in construction, industrial installations, commercial installations, photovoltaic installations and machine control. As you can see, the range of applications is wide and varied, but the common thread is the need to protect networks, people and machines. Since system component requirements vary depending on the application, it helps to know what the market has to offer and what product features to pay attention to.

Switch disconnectors – principle of operation

Switch-disconnectors are used to make and break currents in electrical installations under rated operating conditions. In conduction mode, the role of the disconnector is to supply current to the electrical installation or one of its components. System isolation is achieved by placing the element in a disconnected state. The absence of current flow is associated with the physical opening of the contact and therefore the isolation of the circuit from the power supply. This makes it possible to safely carry out repairs and maintenance of the electrical system or, in industrial conditions, to install a new machine. According to the standard, the design of the switch-disconnector must provide sufficient insulation space between the contacts to completely disconnect the supply voltage. Switch-disconnectors are usually also equipped with a status indicator, which can simultaneously serve as a button and a lever to control the operation of the component.

The main difference between switch-disconnectors and circuit breakers is that the latter only disconnect the circuit above a certain current, and this mainly to protect electrical equipment against short circuits and overloads. On the other hand, switch-disconnectors are mainly used to cut off the power supply; however, fuse disconnects in the form of a fuse placed in the device housing are also available. It blows when the load is too high, which can occur, for example, as a result of a short circuit in the system, providing additional protection for devices connected to the installation.

How to choose the switch-disconnector?

When choosing a disconnector, the first thing that catches your eye is the fact that there are a multitude of products and suppliers on the market, including leading companies and smaller manufacturers. The market offers a wide range of available versions, mounting options and operating parameters. This is due to the fact that manufacturers constantly spend a lot of effort on technological development, improving performance and reliability parameters, and using ever better materials. All of these activities are part of several major trends observed in the field of electrical circuits, such as miniaturization, improved design, ease of assembly and use. At the same time, the environmental resistance and durability of components increase, thereby expanding the scope of application.

It is worth taking a moment to select the right disconnector for the intended application. They are an important part of electrical systems, affecting safety, so it is advantageous to choose high-quality products. Do not be tempted to compromise between quality and price, as a faulty or poorly manufactured disconnector can lead to a dangerous situation or malfunction of the installation.

When choosing the switch-disconnector the expected operating conditions of the circuit must of course be taken into account. One of the main parameters of disconnectors is the rated current, that is, the maximum current that a device should ever consume. The market offers general-purpose components designed for currents of 25 or 32 A. There are also products capable of withstanding large currents and voltages and withstanding amperage of several hundred amperes. Additional parameters given by manufacturers include rated short-circuit making current and rated short-time withstand current. Detailed information is usually available in the manufacturer’s documentation.

It depends on Electrical Installation type switch-disconnectors with a specific number of poles are selected. For a single-phase installation, single-pole or double-pole disconnectors are used, capable of cutting a selected section or the entire electrical installation, respectively. For three-phase current, use three-pole or four-pole disconnectors which, like the previous group, can cut off the power supply to an entire selected section or to the installation.

Functional characteristics are a separate class of switch-disconnector parameters. These devices are offered in a variety of housings, sizes, connection types, mounting and control. Consumers benefit by being able to optimally select the device in terms of dimensions, ease of installation and maintenance. The most common models are DIN rail or panel mounted. In line with current construction and industry trends, models with extensive communication capabilities, enabling effective monitoring and control, are available in the market.

Switch-disconnector – what to look for? ?

Next to switches and disconnectors, switch-disconnectors are the basic elements used to control the current in an electrical installation. In most cases, they are essential to ensure the safety of people and machines, so they should be taken into account in the design and proven, tailor-made solutions used. Once you have chosen the right technical parameters, it is also a good idea to ensure that the products meet the requirements of the IEC/EN 60947-1 standard. This guarantees that a given piece of equipment complies with safety standards. Mention should be made, for example, of the requirement that switch disconnectors must be designed in such a way that the user cannot even accidentally touch live parts. Failure to comply with these standards may affect the safety of people working on the installation.

Yes switches are to be used in harsh environments such as industry or outdoor applications, it is worth choosing products with additional safety certification for electrical products. In such cases, the IP protection code is of great importance.

Text prepared by Transfer Multisort Elektronik Sp. zoo

https://www.tme.eu/en/news/library-articles/page/44881/switch-disconnectors/