COMBI521
EN - 137
CAUTION
The instrument must be used to measure fault loop impedance values at
least 10 times higher than the resolution value of the instrument in order to
minimize errors.
Depending on the set values of nominal voltage (see § 5.1.3) and the measured value of
fault loop impedance, the instrument calculates the
minimum value
of the prospective
short-circuit current to be interrupted by the protection device. For proper coordination, this
value MUST always be greater than or equal to the
Ia
value of the tripping current of the
type of protection considered.
The
Ia
reference value depends on:
Protection type (curve)
Rated current of the protection device
Time of fault extinction by the protection
The instrument allows the selection (*) of the following parameters:
MCB curve B
3A, 6A, 10A, 13A, 15A, 16A, 20A, 25A, 32A, 40A, 45A, 50A, 63A,
80A,100A,125A,160A,200A
MCB curve C
0.5A, 1A, 1.6A, 2A, 3A, 4A, 6A, 10A, 13A, 15A, 16A, 20A, 25A, 32A,
40A, 50A, 63A, 80A,100A,125A,160A,200A
MCB curve D, K
0.5A, 1A, 1.6A, 2A, 3A, 4A, 6A, 10A, 13A, 15A, 16A, 20A, 25A,
32A, 40A, 45A, 50A, 63A, 80A,100A,125A,160A,200A
Fuse gG
2A, 4A, 6A, 8A, 10A, 12A, 13A, 16A, 20A, 25A, 32A, 35A, 40A, 50A, 63A,
80A, 100A, 125A,160A, 200A, 250A, 315A, 400A, 500A, 630A, 800A, 1000A, 1250A
Fuse aM
2A, 4A, 6A, 10A, 12A, 16A, 20A, 25A, 32A, 35A, 40A, 50A, 63A, 80A,
100A, 125A,160A, 200A, 250A, 315A, 400A, 500A, 630A
Time of fault extinction by the protection selectable among:
0.1s, 0.2s, 0.4s, 1s, 5s
(*) The values could be subject to variations
