Figure 5.1.5: Test result with limit value not met
The test will not be carried out if a voltage is
present at the test leads. The test instrument
indicates the following, together with an addi-
tional acoustic signal when starting the test.
Figure 5.1.6: Foreign voltage present
5.2 Testing the Insulation Resistance
The insulation test must be carried out for all elec-
trical installations before initial operation. This test
is of basic importance as the insulation test is used
as the unique measure for fire protection. A limit
fault current being active between two conductors
due to an insulation error leads to a heating up or
even to igniting a fire. Only the insulation test can
detect such a failure.
Figure 5.2.1: Insulation test examples:
In compliance with DIN VDE 0100, Part 610, the in-
sulation resistance test is carried out:
•
For all external conductors (e.g. L1, L2, L3) to-
wards ground or towards the grounded protec-
tive conductor (PE)
•
Between protective conductor (PE) and neutral
conductor (N).
Additionally, the following test should be carried
out:
•
Between all active conductors
(e.g. L1, L2, L3, N).
This test has to be carried out individually for each
single current circuit. The measurement is per-
formed at a DC voltage of 500 V.
Prior to any insulation test it must be ensured
that the system parts to be tested are not live.
12
Testing the Insulation Resistance
PTDB90510001.qxd 02.03.2006 12:23 Uhr Seite 56
