TeraOhm 5kV
16
I
L
I
L
I
L
Ut
Ut
I
A
I
A
I
M
I
M
A
A
LIGHT
ON/OF
F
ESC
MEM
SELECT
START
INSULATION
RESISTANCE
TeraOhm 5kV
VOLTAGE
DIAGNOSTIC
TEST
VOLTAGE
STEP
VOLTAGE
WITHSTANDING
CONFIG
1
2
3
4..8
9
10
+ (Red)
Guard
- (Black)
Fig. 7.
Connection of GUARD terminal to measured object (an example for measuring
cable insulation is shown)
where:
Ut ........Test voltage
I
L
.........Leakage current (resulted by surface dirt and moisture)
I
M
.........Material current (resulted by material conditions)
I
A
.........A-meter current
Result without using GUARD terminal: R
INS
= Ut / I
A
= Ut / (I
M
+ I
L
) …incorrect result.
Result using GUARD terminal:
R
INS
= Ut / I
A
= Ut / I
M
……correct result.
It is recommended to use the GUARD connection when high insulation resistance
(>10G
Ω
) is measured.
Note:
•
Guard terminal is internal impedance (300 K
Ω
) protected.
5.3. Filter option
Filters are built in to reduce the influence of noise on measurement results. This option
enables more stable results especially when dealing with high Insulation Resistances.
The table below contains a definition of the individual filter options:
