fuses

Fuses in medium and low voltage electrical circuits are used to protect devices against the effects of short circuits and overvoltages, which is why they are one of the most important (from the point of view of safety and efficient operation) elements of electrical installations. The main application of the fuse is to interrupt the flow of electricity in order to prevent such effects as electric shock, explosion or fire, as well as damage to the installation or devices connected to it.

Basic types of fuses

The types of fuses differ, e.g. because of the working principle.

On this basis, we can distinguish:

1. fuses – one of the most frequently used in apartments, houses and workplaces. They work in such a way that they turn off the electrical circuit when the value of the current flowing through it exceeds a certain limit. Then, the fuse element, which is placed in the appropriate insert, heats up. This element melts (hence the name), and thus the electrical circuit loses its continuity and breaks. Heating and melting of the fuse occurs faster with a higher value of current in the circuit. Fuses are designed to turn off the electrical circuit when a short circuit occurs and the current is too high, which is why they are designed with a specific value in mind. As a result, sometimes (e.g. when the electrical installation malfunctions) they may turn off when a high-power device is connected to the network.

2. overvoltage fuses (also called plugs due to their round shape and the form of connecting to the fuse board) – they can be found both in older and newer installations. Like fuses, they are designed to cut off the power supply in the event of an overvoltage or short-circuit. The difference is that these solutions apply to the entire circuit with electricity in the house. The overvoltage fuse box is most often placed outside the house or on the cage of the block, to, for example, easily cut off the power supply in the event of a fire. Such devices protect against burnout of wires in the walls and fire of an overloaded installation. They are most often installed where there is an external lightning protection system, but they also work well in buildings powered by overhead or cable lines (e.g. in industrial plants), where many devices operate simultaneously for a long time. Overvoltage fuses are marked with the first letters of the Polish alphabet.

These devices are:

1. 1. class A – for use in protecting overhead lines in low voltage transmission networks (they are not used in flats or houses),
   2. class B – for use in domestic installations,
   3. class C – to devices with higher starting (because they withstand higher initial load),
   4. class D – often used in the case of sensitive electronic devices (they are mounted in flush-mounted boxes and sockets).

3.  residual current fuses– are modern solutions, the most important task of which is to protect the inhabitants of buildings against direct contact with electricity. The fuse mechanism works in such a way that it turns off the entire circuit if only the value of the current flowing into it is not equal to the value of the current flowing out of it. This means that any disturbance results in switching off the circuit. Residual current fuses are used in newer buildings. In older buildings, this is usually only possible after appropriate modification of the electrical installation. Important: after a fuse blows (regardless of its type), in addition to replacing it, it is also recommended to professionally check what led to this condition. If there is a failure in the installation, replacing the fuse will not be sufficient.

Fuses and circuit breakers

Fuses and overcurrent circuit breakers fulfill the same task in the electrical installation, i.e. protection against the effects of overvoltages and short circuits (overcurrent circuit breaker – similarly to a fuse - it automatically disconnects the protected circuit, and its operation is when the current flowing in the wires exceeds the set safe value or when a short circuit occurs). The use of automatic overcurrent circuit breakers (instead of fuses) can be found more and more often in home switchboards, located behind the meter and constituting part of the electricity consumer's installation. The main protection, i.e. the protection located in front of the meter, is most often implemented based on the use of fuse links (fuses).

The el12.pl offer in the FUSES category includes the following products:

• CBs with "B" characteristic - for receivers insensitive to thermal overloads, with low starting currents, this is the most standard group used for residential solutions, they are used to protect devices with low starting currents, e.g. socket, lighting circuits;
• CBs with "C" characteristic - for powering low-power motors (up to several kilowatts), used to protect devices with increased starting currents, mainly used in industrial solutions, e.g. for starting motors;
• circuit breakers with "D" characteristic - typical industrial application, they protect power devices with high starting currents, designed for high power motors;
• fusible links (including installation and power links qq);
• fuse sockets and accessories (such as: fuse base, fuse head, calibrating insert, auxiliary contacts, spanner for calibrating inserts, reducing insert, fuse socket insulating cover, signaling microswitch, insulating partition for fuse bases, fuse holder with protective sleeve);
• Power fuse bases qq;
• Selective automatic circuit breakers.

In addition, in the OTHER FUSES subcategory, el12.pl offers: screw-type circuit breaker, overcurrent circuit breaker (1, 2, - 3, 4 pole), power limiter, installation switch, overcurrent circuit breaker current.

Main fuse, i.e. the basis for home security The most important element of the electrical installation is the main fuse, which allows for trouble-free operation of all devices that consume electricity. In order to properly fulfill its role, the so-called the value of the main switch, which should meet several requirements. First of all, it should not be too high (to avoid unnecessary loss of electricity), but also not too low (to avoid frequent interruptions in the operation of the installation). The value of the main switch corresponds to the maximum possible electricity that can be consumed in the house: the higher its value, the more electrical appliances can be used at the same time. The value of the main circuit breaker is easiest to calculate by adding the power of the devices that operate simultaneously. Most often, these will be: a refrigerator, a TV set, a computer, a washing machine, a dishwasher, lighting and other devices (e.g. heating devices powered from the power grid). You should also not forget about lighting and possibly powering the electric boiler, water heater and air conditioning. The value of the main switch should correspond to the maximum intensity of electricity in the house. The higher its value, the more electrical devices can be used at the same time.