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;
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.
Characteristic | B | C | D |
I1 (t>1h)I2 (t<1h) I3 (t>0.1s) I4 (t<0.1s)
| 1.13xIn1.45xIn 3xIn 5xIn
| 1.13xIn1.45xIn 5xIn 10xIn
| 1.13xIn 1.45xIn 10xIn 20xIn |
Table 1: Opening values of B, C, D type breakers (In: rated current)