MEATEST
M-140 Multifunction Calibrator
Operation manual v46
53
Calibration mode
The multifunction calibrator includes a calibration procedure, which allows calibration of the calibrator. Zero point
and slope of the characteristics of individual generation and measurement ranges are set during the calibration in
predefined order. The calibration can only be controlled using the buttons and menu on the calibrator.
The calibration mode includes AUTOCAL autocalibration function. This function can automatically correct the
short-term instability of zero point for voltage ranges up to 20 V. This function is not a part of the complete
calibration procedure, but it can be used to reduce the time and temperature dependent drift of zero point when
calibrating using small DC voltages and when simulating the thermocouples.
Calibration principles
The calibrator can be calibrated:
•
completely, i.e. all functions are calibrated in all recommended points
•
partially, i.e. only selected functions are calibrated in all recommended points
•
partially, i.e. only selected functions are calibrated in selected points
Complete calibration consists of all partial calibrations performed in the order defined by the calibration menu. If
an item of the calibration menu, e.g. “VOLTAGE DC” is selected, it is not necessary to calibrate all ranges defined
by the calibration algorithm. If new calibration of all ranges is not possible (e.g. the required standard is not
available), old calibration data can be confirmed, i.e. current step of the calibration can be skipped.
DC voltage
calibration is performed by setting the zero and slope of the scale in all ranges and in both signal
polarities (+ and -) (except the 1000 V range, where zero correction is not necessary).
AC voltage
calibration is performed by setting the zero and slope of the scale in all ranges at 1000 Hz (except the
1000 V range, where the calibration is performed at 500 Hz).
DC current
calibration is performed by setting the zero and slope of the scale in all ranges and in both signal
polarities (+ and -).
AC current
calibration is performed by setting the zero and slope of the scale in all ranges at 1000 Hz (except the
20 A, where the calibration is performed at 120 Hz).
AC and DC
power
calibration is performed by calibration of DC and AC current. The phase relationship of
voltage and current (power factor) is defined digitally and cannot be calibrated. It can only be checked. The
respective check is not included in the calibration procedure.
Resistance
calibration is performed by setting the zero and slope of the scale in all ranges. Slope of each range is
calibrated twice. In practice, 9 internal range resistances must be measured and the measured value entered into
the calibrator; then the zero point of the scale is adjusted for each range. Calibration of resistance ranges must be
performed through AUXILIARY connector using Option 70 adapter in resistance range below 100 k
and without
the adapter directly from front panel terminals Hi – Lo in range above 100 k
.
Capacitance
calibration is performed by setting the zero and slope of the scale in all ranges. Slope of each range
is calibrated twice. In practice, 9 internal capacitance ranges (1 nF to 10
F) must be measured and the measured
value entered into the calibrator; then zero point of the scale is adjusted for each range.
Frequency
function calibration is performed by calibration of DC voltage range and zero point check. DC voltage
levels are checked, between which the calibrator switches when generating the signal. The accuracy of PWM of
Calibration interruption can be performed in any point of the calibration
procedure. However this particular calibration influences parameters of the
calibrator.
Accuracy of the calibrator is guaranteed when full calibration was done.