ETCR 3000, Manual, Page: 14 / 20

-11-
There are 3 types of display modes for earth ground resistance
measurement:
P
：
---- Average Value Display
H
：
---- Maximum Display
L
：
---- Minimum Display
The default display on booting is average value, and press MODE button
to switch display mode.
Precision measurement earth ground resistance adopts three-wire
connection. After connection of auxiliary earthing rod and testing wires, set
FUNCITON rotary switch to "2000
Ω
", press "START" button to start
measuring. During measurement, LED indicator flashes, LCD count down
displays, and after measurement, LCD displays measured values. If the
display values are too small, set it to "200
Ω
", "20
Ω
" in turn, that is to choose
the most appropriate gear position for measurement. The value displayed on
the most appropriate position is the measured earth ground resistance value.
After measurement, press MODE button to check for the maximum,
minimum and average value in this measurement.
After measurement, it may delete current measured values by pressing
CLR button.
7
．
Simple Measurement
When select commercial use power supply system earth as auxiliary
earth electrode, it must use detector to confirm that is it the earth ground
electrode for commercial use power supply system.
It is forbidden to use this Tester to confirm earth electrode of commercial
use power supply system
This method is a simple method for measurement that does not use
auxiliary earthing rod, taking the earth electrode with the minimal existing
earth ground resistance value as auxiliary earth electrode, and connecting by
two simple testing wires (in which C, P interfaces are in short circuit). It can
make use of metal pipes, fire hydrants and other metal buried objects,
common earthing of commercial electric power system or lightning protection
earth ground electrode and others to replace auxiliary earthing rods C, P, and
pay attention to remove oxide layer on the connection point of the selected
metal auxiliary earthing object when making measurement.
Earth ground resistance simple testing wire connection is as following
figure, and refer to precision measurement for other operations.