Determining An Svi Positioner Compliance Voltage In A Control System; Compliance Test Set-Up - Baker Hughes Masoneilan SVI II ESD Quick Start Manual

C. Determining an SVI Positioner
Compliance Voltage in a Control System
This discussion explains how to determine compliance voltage for an SVI positioner. It applies to
the SVI II AP, SVI II ESD, SVI II APN and SVi1000.
A definition of compliance voltage is: The voltage that must be available at the control system out-
put in order to drive the control current through the SVI II AP and all the resistive devices in series
with it.
Measuring the voltage across the SVI II AP terminals doesn't give the true available system com-
pliance 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 compli-
ance 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 as at 20 mA this
equals 20 VDC, which is a sufficient maximum.

Compliance Test Set-Up

1. Configure a test setup as in Figure 27.
2. Send 4 mA to the test set-up.
3. Increase the potentiometer value until the loop current reaches 3.95 mA.
4. Read the voltage across the potentiometer, which should be > 11 VDC. This is the
available system voltage at the minimum output.
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Figure 27 Compliance Voltage Test Set-Up
Masoneilan SVI II ESD Quick Start Guide =| 97