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09
®
®
10
1. LCD 2. Button area
3. Rotary switch for selecting function 4. RS232 interface
5. Interface of testing wires 6. P
(S)
interface: Voltage electrode
7. C
(H)
interface: Current electrode 8. E interface: Earth electrode
9. ES interface: Auxiliary earth electrode 10. Standard test wires
11. Auxiliary earthing rods 12. Simple test wires
1. Progress bar (Dynamic display the progress of testing)
2. Alarm symbol (Display when open alarm function, flash when
exceed the alarm value)
3. Exceed voltage symbol (Display when the measured voltage
exceed 30V, please pay attention to the safety)
4. AC symbol
5. Data hold symbol (Display when press to hod data)
6. Data access symbol (Display when long press for at least
least 3 seconds to access data)
7. Data storage symbol (Display when press to hold data
and store)
8. Interference signal symbol (Display when the interference
voltage exceed 5V)
9. Low battery symbol (Display when the battery voltage decreases
to 7.5V)
MEM
MEM
MEM
10. Display the group number of stored data, and display
countdown.
11. Interference electrode symbol (Display when the electrode
exceed 5V interference voltage)
12. Measured data
13. Voltage unit symbol
14. Resistance, soil resistivity, length unit symbol (
W
, k , m,
k
W
m, m)
W
W
V. MEASURING PRINCIPLE :
1. Voltage to ground measurement adopts average value
rectification method.
2. Earth resistance measurement with fall-of-potential method. AC
constant current
I
is applied between the measurement object
E
earth electrode and
C
(H)
current electrode, and finding out the
potential difference
V
between
E
earth electrode and
P
(S)
voltage electrode, calculating the earth ground R according to
formula
R = V/I
. To ensure the accuracy of test, designed the
4-wires method can eliminate influence of contact resistance
(usually result from dirty or rusty) between measured earthing
body, auxiliary earthing rods, test clips, meter’s input interface.
The 4-wires method can also eliminate influence of line
resistance.
Rated current generator
A
~
V
Voltmeter
Voltage electrode
P
(S)
Current electrode
C
(H)
V=R I
´
R=V/I
I
E Earth eelctrode
IV. LCD DISPLAY :
H888
8888
10
20
30
40
0
. . .
.
AC
H
S
HOLD
V
k m
READ
MEM
NOISE
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