MEGABRAS MTD-20KWe, Руководство пользователя

Страница: 15 / 40

17
3. Equipment operation checking
Using a standard resistance (i.e. 10.0
Ω
nominal), it’s possible to test the
equipment calibration. This resistance must be connected to the 4 terminals
on the earth meter, as shown in figure 06.
fig. 06
RX
Following this procedure:
•
The Function Selector Switch
(
must be in the
ρ
position (4 pole).
•
The Range Selector Switch
*
must select the 20.00
Ω
scale.
•
Start the equipment.
•
Press the Battery Test Button
+
to check the battery charge status. If
the display shows a value lower than 1000, the battery should be
recharged or external power supply should be used.
•
Press the Start Pushbutton
'
. After 5 seconds, the display should
indicate a stable value, close to the nominal value of the standard
resistance.
•
If this were not the case, the accuracy of the instrument would be out of
its specification and it would be necessary to adjust by a qualified
laboratory.
•
If you want to calibrate the earth meter in other points of the present
range or of other ranges, adequate standard resistances must be used.
In order to avoid errors by the test leads resistances and their
connections, the 4-wire connection is used (fig 06), with the earth meter
in its measurement function of
ρ
(4 pole). According to the scale, the
highest acceptable error is:
Range Maximum error allowed
0 – 20.00 k
Ω
±(2% of the measured value + 0.2 k
Ω
)
0 – 2000
Ω
±(2% of the measured value + 20
Ω
)
0 – 200
Ω
±(2% of the measured value + 2
Ω
)
0 – 20
Ω
±(2% of the measured value + 0.2
Ω
)