Megger INGVAR, User Manual

Page: 56 / 72

56 ZP-BH05E BH0654BE
10 CALIBRATION
10
C
alibration
10.1 General
You can calibrate the zero levels (offset) for A-meter 1,
A-meter 2 and the Voltmeter. The timer in INGVAR is
crystal controlled and requires no calibration, but can
be checked against an external timer.
The instruments used for calibration should have a
verified high accuracy.
The Control Unit and the Current Unit must be cali-
brated together. It is recommended that you calibrate
your INGVAR system once a year or if the system has
been exposed to extreme variations in ambient tem-
perature.
Regarding calibration of the scale factors we recom-
mend that it is done at 2/3 of the measurement range
or at 2/3 of the highest rated current for your ING-
VAR-system (see output specifications in chapter 11).
You can however calibrate at other values. If accuracy
at a certain value is important you can calibrate at this
value instead.
10.2 Calibration of offset
The zero-offset for Ammeter 1, Ammeter 2 and the
Voltmeter is calibrated.
1]
Disconnect the Current Unit from the Control
Unit.
1]
The input for Ammeter 2 should be open.
2]
Short circuit the voltmeter input (i.e. the
voltage should be 0 V).
3]
Press the
SYS
button.
4]
While simultaneously pressing the buttons
ESC
and quickly turn the Select/set knob
clockwise until "CALIBRATION" appears on
the display.
5]
Press to confirm.
6]
Choose ”Zero-offset”.
7]
Press .
Calibration of zero-offset is done automatically.