Gx
Series
EN - 147
13.7. NO TRIP TEST IN TN SYSTEMS
The protection against indirect contacts in the TN systems must be guarantee by means a
protection device against the overcurrents (typically MCB or fuse) which swich off the
power supply of the circuit or the electrical equipment in case of fault between an active
part and a ground mass or a protection conductor within a interval not exceeding at 5s,
sufficient for the equipments.
Parts of the system to be checked
The test must be performed at the point in which the minimum short-circuit current is
possible, normally immediately downstream of the protection device to be checked.
The test must be performed between phase and PE (Z
L-PE
) and between phase and
neutral (Z
L-N
) in three-phase systems or single-phase systems.
Allowable values
The measurement is aimed at ensuring that in every point of the system the followed
relationships are satisfied:
Z
L-PE
≤
Z
LIM
(1)
Z
L-N
≤
Z
LIM
(2)
where:
Z
L-PE
= Impedance measured between phase and PE
Z
L-N
= Impedance measured between phase and neutral
Z
LIM
=
Maximum limit impedance depending on type (MCB or Fuse) and tripping time
of the selected protection (values depending on countries)
The following selections (*) are available on the instrument:
MCB current (B curve) selectable among values:
3,6,10,16,20,25,32,40,50,63,80,100,125,160,200A
MCB current (C, K, D curves) selectable among values:
0.5,1,1.6,2,3,4,6,10,13,15,16,20,25,32,40,50,63, 80,100,125,160,200A
Nominal current Fuse BS88-2 selectable among values:
2
,
4
,
6, 10, 16, 20, 25, 32, 40,
50, 63, 80, 100, 125, 160, 200A
Nominal current Fuse BS88-3 selectable among values:
5,16,20,32,45,63,80,100A
Nominal current Fuse BS3036 selectable among values:
5,15,20,30,45,60,100A
Nominal current Fuse BS1362 selectable among values:
3,15A
Time of fault extinction by the protection selectable among:
0.1s, 0.2s, 0.4s, 1s, 5s
(*) The values could be subject to variations
