KYORITSU 3127 - Manual (Page 35)

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6-9 Voltage characteristics of measuring terminal
6-10 Use of Guard terminal
When measuring the insulation resistance of a cable, leakage current flowing on
the surface of cable jacket and the current flowing inside the insulator are mixed
and may cause error in insulation resistance value. In order to prevent such error,
wind a conductive wire around the point where leakage current flows.
Then connect it to the Guard terminal as shown in the figure on the next page. This
is to move out the surface leakage resistance of the cable insulation to measure
only the volume resistance of insulator. Make sure to use the Guard cord supplied
with this instrument to connect the instrument to Guard terminal.
0
1000
2000
3000
4000
5000
6000
O
u
tp
u
t
V
o
lt
a
ge
（
V
）
Insulation Resistance
0.1
MΩ
1
MΩ
10
MΩ
100
MΩ
1000
MΩ
10
GΩ
100
GΩ 1000
GΩ
KEW3127 Output characteristics (IR
PI/DAR
mode)
5000V range
2500V range
1000V range
500V range
* for 10sec after a start of test
250V range