11
6.2 Measurements with the Guard Cable
The measurement of very high impedance resistances presupposes extremely
small measurement currents, and problems can occur due to influences such as
electromagnetic fields, moisture or surface currents. For this reason, the mea-
surement set-up must be accurate.
For measurements over 10 G
, the guard cable (cat. no. 45065) is rec-
ommended. It must be used for measurements from 100 G
...1 T in order to
prevent inaccurate measurement results caused by surface currents. The guard
rings prevent current at the surface of the insulation material from flowing from
the + measurement cable to the – measurement cable instead of through the
insulation material itself.
1. Insert guard cable plug into appropriate jack at tester.
2. Plug alligator clip onto guard cable test probe.
3. Clip alligator clip onto guard ring located between both measuring points of
insulation material to be measured.
4. See paragraph 6.1 for measurement procedures.
7. Characteristic Values
Insulation Resistance
.saeM
egnaR
lanimoN
foegnaR
esU
-nepO/.moN
egatloVtiucriC
U
N
U/
0
lanimoN
tnerruC
I
N
C-S
tnerruC
I
K
tnerehnI
noitaiveD
)1
k001 …
M001
k001 …
M01
V001
V052
V005
V0001
Am1Am3.1
%5.2
k01
…
T1
k01 …
T
1
V0051/001
V0002/052
V0052/005
V0005/0001
Am7.0
Am5.0
Am4.0
Am1.0
Am3.1
%5
w ww . . co m
information@itm.com1.800.561.8187
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