BS EN 60898-2:2006 – Electrical accessories — Circuit-breakers for overcurrent protection for household and similar installations — Part 2: Circuit-breakers for a.c and d.c. operation

1 Scope and object
This clause of Part 1 is applicable except as follows:
Addition at the end of the first paragraph:
This standard gives additional requirements for single- and two-pole circuit-breakers which, in addition to the above characteristics, are suitable for operation with direct current, and have a rated d.c. voltage not exceeding 220 V for single-pole and 440 V for two-pole circuit-breakers, a rated current not exceeding 1 25 A and a rated d.c. short-circuit capacity not exceeding 10 000 A.
NOTE This standard applies to circuit-breakers able to make and break both a.c. current and d.c. current.
Delete the last two paragraphs.
2 Normative references
This clause of Part 1 applies.
3 Definitions
Clause 3 of Part 1 applies with the following modification:
Addition:
3.5.10.3
time constant
the rise time T = L/R (ms) of a prospective direct current to reach a value of 0,63 times the maximum peak current
4 Classification
Clause 4 of Part 1 applies with the following modifications:
4.1 According to the number of poles
Replacement:
– single-pole circuit-breakers;
– two-pole circuit-breakers with two protected poles.
4.5 According to the instantaneous tripping current (see 3.5.17)
Delete D-Type.
Addition:
4.7 According to the time constant
– Circuit-breakers suitable for d.c. circuits with a time constant of T ≤ 4 ms.
– Circuit-breakers suitable for d.c. circuits with a time constant of T ≤ 1 5 ms.
NOTE It is assumed that short-circuit currents of 1 500 A are not exceeded in installations in which, due to the loads connected, time constants in normal service up to 1 5 ms can occur. Where higher short-circuit currents may occur, the time constant of T = 4 ms is considered sufficient.
5 Characteristics of circuit-breakers
Clause 5 of Part 1 applies with the following modification:
5.3.1 Standard values of rated voltage
Replacement:
The standard values of rated voltages are given in Table 1 .
Examples of connections of circuit-breakers in d.c. systems are given in Figure 1 8.
BS EN 60898-2:2006 – Electrical accessories — Circuit-breakers for overcurrent protection for household and similar installations — Part 2: Circuit-breakers for a.c and d.c. operation