HT COMBITEST422 User Manual page 103

Depending on the set values of phase-phase, phase-neutral or phase-PE 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 as worst case
The Ia reference value (see Fig. 37) depends on:
➢ Protection type (curve B, C, D, K)
➢ Rated current of the protection device In
➢ Time of fault extinction by the protection
Tipically: Ia = 3÷5In (curve B), Ia = 5÷10In (curve C), Ia = 10÷20In (curves D,K)
Fig. 37: Example of curves relative to magnetothermal (MCB) 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
EN - 103
COMBITEST422