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Measuring the voltage across the SVI3 terminals doesn't give the true available system
compliance voltage as the positioner self-regulates voltage as current flows through it.
Additionally, it also doesn't confirm what system voltage is available under load
conditions. Therefore, if compliance testing needs to be done, it is best done before
installation.
Use a 1K potentiometer as this is the maximum for most analog output cards and at 20
mA this equals 20 VDC, which is a sufficient maximum.
7.5.1 Compliance Test Setup
1. Configure a test setup as in Figure 38.
Figure 38 Compliance Voltage Test Setup
2. Send 4 mA to the test setup.
3. Increase the potentiometer value until the loop current reaches 3.95.
4. Read the voltage across the potentiometer, which should be > 11 VDC. This is the
available system voltage at the minimum output.
5. Send 20 mA to the test setup.
6. Increase the potentiometer value until the loop current reaches 19.95 mA.
7. Read the voltage across the potentiometer, which should be > 9 VDC. This is the
available system voltage at the maximum output.
Loop Current
Falling Off
0Ω 1KΩ
0mA
20mA
Read Vdc when
Current falls off
1KΩ
Control Sy stem
Output Card
4-20 mA
A
A
V
V
Loop Current
20mA
