Sähkökatkaisimet

Sähkökatkaisimet, commonly known as circuit breakers in English, are essential safety devices in electrical systems. Their primary function is to protect electrical circuits from damage caused by overcurrent or short circuits. Overcurrent can occur due to an overload, where too much current is drawn from the circuit, or a short circuit, which is a low-resistance path that allows a large surge of current to flow.

When an excessive amount of current flows through a sähkökatkaisin, it automatically interrupts the flow of electricity. This interruption prevents overheating of wires and components, which could otherwise lead to fires or damage to appliances. Once the fault condition is resolved, the sähkökatkaisin can typically be reset manually to restore power.

Sähkökatkaisimet come in various types, designed for different applications and voltage levels. Common types include miniature circuit breakers (MCBs) used in residential and commercial buildings for lighting and power circuits, and molded case circuit breakers (MCCBs) for higher current applications. There are also residual current devices (RCDs), or vikavirtasuojakytkimet in Finnish, which are specifically designed to detect imbalances in current flow, indicating a potential shock hazard, and trip the circuit.

The design of a sähkökatkaisin usually involves a mechanism that detects the overcurrent and a set of contacts that open to break the circuit. This detection can be achieved through thermal means (a bimetallic strip that bends when heated by excessive current) or magnetic means (an electromagnet that activates a tripping mechanism). The selection and proper installation of sähkökatkaisimet are crucial for ensuring the safety and reliability of any electrical installation. They are a fundamental component in modern electrical safety standards.