Ht-instruments MACROTEST G3 Uživatelský manuál stáhnout pdf (Strana 102)

MACROTESTG3 - COMBIG3

EN - 101

12.11. VERIFICATION OF VOLTAGE DROP ON MAIN LINES

Measurement voltage drop as a result of current flow through a main line or a part of it can

be very important if it is necessary:

 Verify the capability of an existing main line to supply a load

 Dimension a new installation

 Search for possible causes of troubles on devices, loads, etc.. connected to a main line

Purpose of the test

Measure the maximum percentage value of voltage drop between two points of a main

line

Parts of the system to be checked

The test includes two sequential impedance measurements in the initial point of main

power line (typically downstream to a protection device) and in the final point of the same

line.

Allowable values

The instruments compares the calculated value of V% maximum voltage drop to the set

limit value (according to applicable guidelines) according to the following relationship:





100*

NOM12

NOM

MAX





where:

Z2 = End point impedance of the main line being tested

Z1 = Initial point impedance (Offset) of the main line being tested (Z2 > Z1)

INOM =

Nominal current of protection device of the main line being tested

NOM =

Phase-Neutral or Phase-PE nominal voltage of the main line being tested

12.12. MEASUREMENT OF EARTH RESISTANCE IN TN SYSTEMS

Purpose of the test

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Ht-instruments MACROTEST G3 Uživatelský manuál Strana 102