GE AquaTrans AT868, Abridged Manual

Page: 52 / 67

Calibration 4-1
September 2004
Introduction
Follow the instructions in this chapter to calibrate and test the AT868
analog and totalizer/frequency outputs. Refer to
Figure A-4 on page
A-4 in Appendix A, Menu Maps , while following the calibration
instructions.
Calibrating and Testing
the Analog Outputs
The AT868 includes one built-in analog output per channel with a
resolution of 5.0
μ
A (0.03% full scale). Typically,
Output A
is used
for
Channel 1
and
Output C
is used for
Channel 2
. However, either
output can be configured for use with either channel. Both the low
and high values for the analog outputs must be calibrated. After the
end points are calibrated, the linearity should be tested.
Note:
The zero point of the analog output may be set for either 0 mA
or 4 mA. However, the calibration procedure always uses the 4
mA point, as the meter will extrapolate this value to obtain the
0 mA point.
Calibration
Prepare for calibration by connecting an ammeter in series with the
load on analog output 1 or 2 as shown in
Figure 4-1 below. DO NOT
connect the ammeter directly across the terminals. Refer to Figure 1-5
on page 1-16 for the locations of the analog outputs terminal blocks.
Note:
Analog outputs 1 and 2 in the wiring diagram correspond to
analog outputs A and C in the AT868 software.
Figure 4-1: Ammeter Connection
Ammeter
Load
AOUT1 FREQ1