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5-3 Principles of earth resistance measurement
This tester uses two methods to measure earth resistance, which
are 3-pole and 2-pole.
Normal earth resistance measurement uses 3-pole method, which
use 2 auxiliary earth electrodes into the ground.
Earth resistance is measured by the potential drop method. First
apply AC voltage between E and H(C) to measure current “I”.
Second measure voltage “V” between E and S(P).
Rx = V / I
Ammeter
Ammeter
Voltmeter
Voltmeter
Auxiliary earth
electrode
Auxiliary earth
electrode
Auxiliary earth
electrode
Auxiliary earth
electrode
Earth electrode
Earth electrode
AC power supply
AC power supply
E
S
(
P
)
H
(
C
)
V=Rx × I
Rx= V / I
I
V
V
A
A
2-pole method is used when the earth system is known or there
is an known earth resistance, which is very low against object to
measure.
Note:
Optional accessory (TL-68) is required for 2-pole method.
5-4 Zero adjustment
Before earth resistance measurement, set zero (0.00 Ω) reading to
cancel resistance of test leads.
Procedure :
①
Set the function to 40
Ω.
②
Connect the black plug into E
terminal, blue plug into S(P)
terminal and red plug into H(C).
③
Alligator clips are shorted as
illustrated, then press TEST
button.
④
Press REL button, reading
becomes 0.00 with
symbol.
During earth resistance measurement press
button again
or change function,
function will be canceled.
Note:
If reading is 5 Ω or less when pressing REL function, test lead
may be broken.
EARTH TESTER
PDR4000
POWER
REL
HOLD
TEST
ACV
40Ω
400Ω
4000Ω
>
2s
AUTO POWER OFF
TEST OUT PUT
CAT.III 300V
CAT.II 400V
ACV 400V
MAX
E
S
(
P)
H
(
C)
Black
Black
Blue
Blue
Red
Red