English
Tab 1. Tripping characteristics in accordance with the ČSN EN 60898 standard:
| Tripping characteristics | B | short-circuit release | 3 ÷ 5 In | (resistive load) |
| C | 3 ÷ 5 In | (incandescent bulbs, motors) | ||
| D | 10 ÷ 20 In | (motors with a heavy start) |
Tab 2. characteristics B:
| tripping current | tripping time |
| In x 1,13 | "fixed non-tripping current" – the circuit breaker must never switch off |
| In x 1,45 | "fixed tripping current" – the circuit breaker must switch off within 1 hour |
| In x 2 | approx. 30 s |
| In x 3 | 10 s (the short-circuit release can already trip) |
Breaking capacity is the magnitude of current (short-circuit current) that the circuit breaker is able to switch off
repeatedly with no damage (e.g. 6 kA, 10 kA, 15 kA).
All three types of characteristics (B, C and D) differ from each other only by setting the electromagnetic (short-circuit) release. The thermal release area up to the point of the electromagnetic trigger tripping, the shape of the tripping characteristics is identical for all the characteristics.Therefore it is irrelevant from the point of view of long-term.
loading of the line by small over-current what type of circuit breaker (regarding the tripping characteristics) is used.
Fig. 1. Tripping characteristics of modular circuit breakers B, C and D