METREL MI 3399, Instruction Manual With Exercises

Page: 97 / 272

Electrical Installation Safety Trainer AD 1 - MI 3399
97
2.6.2.3 Exercise No. 2.6-3: R
ISO
in an IT system
Measuring procedure
1 To measure the insulation resistance select first the R
ISO
function in the ISO
section.
2 Set the minimum allowed insulation resistance by clicking in the bottom left dark
grey corner.
3
If a schuko commander is to be used, plug the commander into the appropriate
outlet. If the cables are used, connect all cables appropriately
– the PE cable to
the PE conductor, the N cable to Line2 and the L cable to Line1.
During the measurement, check the insulation resistance between all conductors
(L
X
-L
Y
, L-N, L-PE. N-PE).
4 Press the START key.
Expected results
Measuring the insulation resistance in an IT system is done between both Line
conductors. Usually the insulation resistance in a circuit is well above 1 M
Ω.