PLZ-4W Maintenance and Calibration 8-5
8.3 Calibration
The PLZ-4W is shipped from the factory after carrying out a strict calibration. How-
ever, to maintain the performance, periodic calibration is recommended.
8.3.1 Calibration Overview
The calibrated items are current and voltage.
The current is calibrated with respect to the current ranges (3 ranges: L, M, and H).
The voltage is calibrated with respect to the voltage ranges (2 ranges: 15 V and
150 V).
For each range, the offset and gain are calibrated.
Offset:Value corresponding to 10 % of the range full scale
Gain: Value corresponding to 100 % of the range full scale
The relationship between the setting and output during operation is linear. There-
fore, a line is defined by calibrating the offset and gain at 2 points. During operation,
the relationship between the setting and output is achieved along the calibrated line.
Fig. 8-4 Offset and gain calibration
■ Calibration items
The following six items are calibrated for three current ranges and two voltage
ranges.
1. Offset of the internal reference voltage for output setting
2. Gain of the internal reference voltage for output setting
3. Offset of the measured value
4. Gain of the measured value
5. Offset of the internal reference voltage for protection function setting
6. Gain of the internal reference voltage for protection function setting
The offsets of the internal reference voltage for output setting and the measured
value (number 1 and 3) are calibrated simultaneously. The same also holds true for
the gain (numbers 2 and 4).
Therefore, the number of calibration points is 20 (4 points 5 ranges).
Reference value
Ofst
Gain
0
Offset calibration
value
Gain calibration
value
F.S. of range
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