Ht-instruments MACROTEST G3 Instrukcja Użytkownika Pobierz pdf (Strona 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:

aMinLLSC

II 

 2_

Three-phase system  Loop L-L impedance

aMinNLSC

II 

 _

Single-phase system  Loop L-N impedance

aMinPELSC

II 

 _

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:

NOM

MINMinLLSC







NOM

MINMinNLSC





PEL

NOM

PEL

MINMinPESC





Phase – Phase Phase – Neutral Phase – PE

Measured voltage U

NOM

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

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