HT instruments EQUITEST5071 - Manual (Page 23)

EQUITEST 5071
EN - 21
6.4. LOOP/RA : LOOP IMPEDANCE, OVERALL EARTH RESISTANCE AND
PHASE SEQUENCE
Measurement is carried out in compliance with standards IEC/EN61557-3 and
IEC/EN60204-1:2006.
Turn the rotary switch to LOOP/Ra .
With the F1 key it is possible to select one of the following measuring modes
(which cyclically appear when pressing the key):
 “P-N” mode (the instrument measures impedance between Phase
conductor and Neutral conductor and calculates the assumed Phase-
Neutral short-circuit current. This test is usually carried out to evaluate if
the breaking power of switches is higher than short-circuit current in the
installation point).
 “P-P” mode (the instrument measures impedance between two Phase
conductors and calculates the assumed Phase-Phase short-circuit
current. This test is usually carried out to evaluate if the breaking power
of switches is higher than short-circuit current in the installation point).
 “P-PE” mode (the instrument measures the overall earth resistance and
calculates the assumed Phase-Earth short-circuit current. This test is
usually carried out to evaluate the coordination of the protections against
indirect contact by means of an automatic interruption of power supply
and to measure the value of Earth resistance).
 “R
A
” mode (the instrument measures the overall earth resistance and
calculates the assumed Phase-Earth short-circuit current. This test is
usually carried out to evaluate the coordination of the protections against
indirect contact by means of an automatic interruption of power supply
and to measure the value of Earth resistance. This test has a lower
resolution than “P-PE” test, but has the advantage that it can be carried
out without making a possible residual current protection, installed
upstreams of the measuring point, trip).
 “
” mode (the instrument detects phase sequence).
CAUTION
When message "MEASURING…" is displayed, this indicates that the
instrument is carrying out the test. Never disconnect the instrument’s leads
during this phase.