59
- if there is no tripping of a earth fault breaker (measurement made upstream of the
RCDs),
- if the earth fault breaker concerned is short-circuited for greater accuracy,
- in the case of a selective measurement using a current probe.
→
low (
) for a quick check :
→
Make the connections as indicated below, according to the type of installation to be checked.
→
Compensate the measuring cables (see § 3.3),
Case of an installation with a TT type neutral situation:
→
Connect the mains socket (or the 3 separate cables) to the
installation to be tested,
→
Plant the auxiliary rod at a distance > 25m from the earth
electrode.
Case of an installation with a TN type neutral situation (selective measurement):
→
Connect the mains socket (or the 3 separate cables) to
the installation to be tested;
→
Connect a current probe to the
terminal and encircle
the earth of which the resistance is to be measured: the
current used to calculate Z
E SEL
is that measured by the
probe;
→
Plant the auxiliary rod PE as close as possible to the
earth electrode to be measured for a measurement that is
as accurate as possible;
→
Compensate the cables.
Note:
without the current probe, what is measured is the
global earth of the network, which is not very significant.
Case of an installation with an IT type neutral situation (not isolated):
Preliminary remarks:
-
the power supply transformer of the installation must not be completely isolated, but earthed
through an impedance,
- the installation must also not be in first fault: start by checking the indication of the
Permanent Insulation Tester concerned,
-
the "grounds to earth" R
E
and the earth of the power supply transformer must be separate to
allow the circulation of the measuring current.
Summary of Contents for C.A 6454
Page 3: ...2...
