USAGE PLACES OF B-C-D TYPE MINIATURE CIRCUIT BREAKERS

USAGE PLACES OF B-C-D TYPE MINIATURE CIRCUIT BREAKERS

Usage places of B-C-D type Miniature Circuit Breakers

Miniature circuit breakers are used to protect the electrical installation they are connected to against over-current and short circuit. They open the circuit automatically due to the thermal and magnetic protection feature they contain during over-currents above any of the nominal (declared) currents or during any short circuit.

What are the main differences between B, C and D type miniature circuit breakers? Why do the areas of use vary?

Type B breakers are generally used in the protection of lighting and socket circuits where sudden over-currents do not occur during switching, such as home lighting with incandescent filaments and electrical heaters. Type C and D breakers are generally used for the protection of inductive circuits, transformers, air conditioners, refrigerators and many fluorescent lamps where sudden over-currents occur during switching or activation.

If generally to be specified;

• Type B breakers in residences,

• C type breakers are used both for protection of some devices in the residences and in industrial areas,

• D type breakers are used only in industrial areas.

Magnetic opening level of B type breakers against sudden over-currents are lower than C and D types.

For example, a type B 16A breaker will open without delay at an over current of 48A to 80A, while a type C 16A breaker will open the circuit without delay at a current value between 80A and 160A, and a type D 16A breaker between 160A and 320A.

Table 1: Opening values of B, C, D type breakers (In: rated current)