HT instruments MACROTEST G3 - Manual (Page 99)

MACROTESTG3 - COMBIG3
EN - 98
12.9. VERIFY OF PROTECTION COORDINATION L-L, L-N AND L-PE
Purpose of the test
Test the coordination of protective devices (typically MCB or fuse) present in a Single-
phase or Three-phase installation as a function of the limit time of fault extinction by the
protection set by the user and the calculated value of the short-circuit current.
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 at the end of the line controlled by the protection device in the normal
condition of the line. The test must performed between Phase-Phase in the Three-phase
installations and between Phase-PE or Phase-PE in the Single-phase installation
Allowable values
The instrument performs the comparison between the calculated value of short-circuit
current and the Ia = tripping current of the protection device within the specified time,
accordinf to to following expressions:
a Min L L SC
I I

 
2 _
Three-phase system  Loop L-L impedance
a Min N L SC
I I

 _
Single-phase system  Loop L-N impedance
a Min PE L SC
I I


_
Single-phase system  Loop L-PE impedance
where:
Isc L-L_Min2F = Prospective short-circuit current minimum double phase L-L
Isc L-N_Min = Prospective short-circuit current minimum L-N
Isc L-PE_Min = Prospective short-circuit current minimum L-PE
The calculation of prospective short-circuit current is performed by the instrument based
on the fault loop impedance measurement in compliance with the following relationships
derived from standard EN60909-0:
L L
NOM
L L
MIN Min L L SC
Z
U
C I


 
 
2 _
N L
NOM
N L
MIN Min N L SC
Z
U
C I



 
_
PE L
NOM
PE L
MIN Min PE SC
Z
U
C I



 
_ L
Phase – Phase Phase – Neutral Phase – PE
Measured voltage U
NOM
C
MIN
230V-10% < Vmeasured < 230V+ 10% 230V 0,95
230V+10% < Vmeasured < 400V- 10% Vmeasured 1,00
400V-10% < Vmeasured < 400V+ 10% 400V 0,95
where:
U L-L = Nominal Phase-Phase voltage
U L-N = Nominal Phase-Neutral voltage
U L-PE = Nominal Phase-PE voltage
Z L-L
= Impedance Phase-Phase measured
Z L-N = Impedance Phase-Neutral measured
Z L-PE = Impedance Phase-PE measured