Electrical Cabinets and Modular Circuit Breakers
Electrical Cabinets and Modular Circuit Breakers
The electrical distribution board connects every point of an electrical system, and is responsible for safety, signalling, and controlling the circuits. Considering all these essential functions, the switch cabinet must be equipped with high-quality components. A well-designed, neatly built cabinet that follows best practices is not only a source of pride for electricians but also guarantees full safety for users.
A classic electrical cabinet is equipped with electrical components, which can be classified as:
- switching devices
- measuring devices
- signalling devices
- protective devices
- control devices
Components of Electrical Cabinets - Functions
All incoming and outgoing electrical cables in the distribution cabinet complete the electrical circuit, as they pass through the devices installed inside. This is the cabinet’s first function: dividing pre-designed zones into separate electrical circuits.
Why is this so important? Let’s take a family home as an example. One of the most important reasons is that the lighting circuit can be separated from the sockets. When you need to replace a lamp, you can turn off the lighting circuit for that room while still using a drill plugged into a socket that remains powered. Also, if the rest of the house is on separate circuits, residents do not have to sit in the dark, as lighting will still work elsewhere.
Distribution boards also perform measurement functions. This is not only for measuring the amount of electricity used but, in advanced systems, also for running smart energy management features, as well as enabling remote monitoring or control of the entire electrical system based on various parameters.
The cabinet also has components that indicate the presence (or absence) of voltage in a given circuit. These usually use display units with colour codes to inform the user about different statuses.
Finally, we must mention one of the most important features of distribution boards - protection. Everyone knows the importance of components that protect users from electric shock caused by a short circuit. They safeguard human life, health, and property, since a short circuit can cause both electric shock and fire. Many components in the cabinet are dedicated to short-circuit, overload, or surge protection.
The role of control devices should also be noted. They make it easier to automate control of electrical loads, such as turning the power supply on or off temporarily, controlling twilight lighting sensors, or adjusting current levels.
All these functions are carried out by different devices housed inside the electrical cabinet. The correct operation of the entire system usually depends on their quality, accuracy, and reliability. This is why it is worth looking closely at the parameters and features of modular devices offered by leading manufacturers.
Modular Devices - Types and Uses
Modular devices are cube-shaped components of standard dimensions designed to perform different functions in an electrical system. Their uniform mounting size allows them to be easily installed on DIN rails. A major advantage of having the same standards is that parts from different manufacturers are compatible and can be used together to create a working system. Features such as very easy assembly and disassembly, and independence from other cabinet elements, make modifications and replacements simple.
Residual Current Circuit Breakers (RCCBs) are among the most important and indispensable components in any electrical box. They work by cutting the power if they detect a “differential current” (voltage) on an appliance casing. This usually happens when an insulation fault causes voltage to appear on metal parts of the casing. In such cases, there is a direct risk of electric shock or fire. To prevent this, the device detects the difference in current between the live and neutral conductors and disconnects the supply.
Overcurrent Circuit Breakers protect systems from the harmful effects of current exceeding the allowed value. They also trip in the event of a short circuit, automatically cutting power. Key parameters include the number of overcurrent circuits and poles, as well as the rated current. The breaker’s time-current characteristic is particularly important, as it defines the time and current level at which the breaker must disconnect the supply.
Motor protection circuit breakers, also known as thermal overload relays, are designed to protect electric motors. They are typically used in workshops or industrial plants operating large electric motors. They instantly cut the power in case of a short circuit, overload, or phase loss. Motor breakers also ensure safe starting of machines and make motor control and monitoring easier.
Surge Arresters are essential for protecting electrical devices connected to the network. Often referred to as lightning arresters, they are designed to limit the voltage in the network and keep it at a safe level for consumers. The right module can protect devices from surges caused by nearby lightning strikes. Sensitive electronic equipment can be affected even by small voltage fluctuations, so surge arresters are designed to provide full protection against such effects.
Isolator Switches are used to disconnect the power supply in industrial-grade control cabinets. They are usually mounted on the cabinet housing so that power can be cut without opening the cabinet. Since they often operate in harsh environments, these switches have high IP ratings and are placed in the operator’s field of vision. This is especially important in emergencies, where immediate action is needed.
