HT instruments MACROTEST G3 - Manual (Page 94)

MACROTESTG3 - COMBIG3
EN - 93
12.5. VERIFY OF THE BREAKING CAPACITY OF PROTECTION DEVICES
Purpose of the test
Checking that the breaking capacity of the protection device is higher than the maximum
fault current possible in the system.
Parts of the system to be checked
The test must be performed at the point in which the maximum short-circuit current is
possible, normally immediately downstream of the protection device to be checked.
The test must be performed between phase and phase (Z
pp
) in three-phase systems and
between phase and neutral (Z
pn
) in single-phase systems.
Allowable values
The instrument performs the comparison between the measured value and the value
calculated according to the following relationships derived from standard EN60909-0:
2
3
3
L L
NOM
L L
MAX MAX Z
U
C I BC



  
N L
NOM
N L
MAX N L MAX
Z
U
C I BC



  
Three-phase systems Single-phase systems
where:
BC = breaking capacity of protection device
Z
LL
= Impedance measured between phase and phase
Z
LN
= Impedance measured between phase and neutral
Measured voltage U
NOM
C
MAX
230V-10% < Vmeasured < 230V+ 10% 230V 1.05
230V+10% < Vmeasured < 400V- 10% Vmeasured 1.10
400V-10% < Vmeasured < 400V+ 10% 400V 1.05