Calibrating And Testing Analog Outputs; Preparing For Calibration - GE DigitalFlo XGM868i Service Manual

Chapter 1. Calibration

1.3 Calibrating and Testing Analog Outputs

Every Model XGM868i flowmeter includes two built-in analog outputs (A and B) at terminal block J1, which is
designated as Slot 0. Additional analog outputs may be added to the Model XGM868i by installing an appropriate
option card in Slot 1. This option card contains two analog outputs, which are also designated as A and B.
Before beginning calibration, an ammeter must be connected to the desired analog output. Both the zero-point and
full-scale values for all of these outputs must be calibrated. After calibrating the outputs, which have a resolution of 5.0
A (0.03% full scale), their linearity should be tested.
Note: The zero point of the analog output may be set at either 0 mA or 4 mA. However, the calibration always uses
the 4 mA point, as the meter extrapolates this value to obtain the 0 mA point.

1.3.1 Preparing for Calibration

Prepare for calibration by inserting an ammeter in series with the load on the desired output. Refer to Figure 1 and
Figure 4 on page 12 to identify the OUT(+) and RTN(-) pins for the desired output.
2
Terminal Block J1 (Slot 0)
4
B B
RTN SIG RTN
Figure 1: Ammeter Connection (Output A)
1
A A
SIG
Load
- +
Ammeter
DigitalFlow™ XGM868i Service Manual