Loop: Line/Loop Impedance And Overall Earth Resistance - HT EASYTEST User Manual

6.7.

LOOP: LINE/LOOP IMPEDANCE AND OVERALL EARTH RESISTANCE

This function is performed in compliance with standard IEC/EN61557-3, BS7671 17th/18th
edition and allows measuring the line impedance, the fault loop impedance and the
prospective short-circuit current.
Depending on the selected electrical system (TT, TN or IT), some
connections and function modes are disabled by the instruments (see Table
2: Conditions of positive outcome depending on the test parameters).
The following operating modes are available:
• L-N
Standard (STD) measurement of the line impedance between the phase
conductor and the neutral conductor and calculation of the prospective
phase-to-neutral short-circuit current.
• L-L
Standard (STD) measurement of the line impedance between the two phase
conductors and calculation of the pospective phase-to-phase short-circuit
current.
• L-PE
Standard (STD) measurement of the fault loop impedance between the
phase conductor and the earth conductor and calculation of the prospective
phase-to-earth short-circuit current.
• Ra
Fault loop impedance without causing the protections' tripping in TN systems
(see § 12.7) and overall earth resistance (TT systems) with neutral (3-wire)
and without neutral (2-wire) (see § 12.8).
The instrument checks voltage on PE by comparing the voltage at B4 input
and the ground potential induced on the instrument's side through the user's
hand. Therefore, in order to check voltage on PE, it is mandatory to hold
the instrument case on the left or on the right side.
The measurement of line impedance or fault loop impedance involves the
circulation of a maximum current according to the technical specifications of
the instrument (see § 10.1). This could cause the tripping of possible
magnetothermal or differential protections at lower tripping currents.
Fig. 23: P-N/P-PE test for single-phase/two-phase 230V systems with mains plug
CAUTION
CAUTION
CAUTION
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EASYTEST-COMBI519