Grounding Practices; Compliance Voltage In Single Drop Current Mode; Verify Wiring And Connections - GE SVI II AP-2 Quick Start Manual

Installation and Set Up

Grounding Practices

To ensure proper grounding make sure that case, signal, and ground connections
are made in compliance with the plants normal grounding practices. Any point in
the loop can be referenced to ground, but there must never be more than one
ground point. Normally ground is connected at the controller or at the intrinsic
safety barrier.
The case grounding screws are located on the outside of the case at the lower
right of the display cover and inside the cover. The case is isolated from all
circuitry and can be grounded locally in accordance with applicable codes.
If noise or instability is present, set the positioner to MANUAL mode of operation
and manually position the valve over its entire range. If the valve is stable in
MANUAL mode then the problem can be noise in the control system. Recheck all
wiring connections and ground points.

Compliance Voltage in Single Drop Current Mode

The SVI II AP requires 9.0 V at 20 mA and 11.0 V at 4 mA. Typical HART devices
require MORE Voltage at higher current and MORE current source have LESS
Voltage available at higher current. The SVI II AP is noteworthy in that it requires
LESS Voltage at higher current that complements the characteristic of the source
requiring only 9 V at 20 mA.

Verify Wiring and Connections

NOTE
Use the following procedure to ensure that the SVI II AP is properly powered:
1. Connect a DC voltmeter across the input terminals.
2. Connect a milliampmeter in series with the current signal.
3. Verify that source can supply 20 mA to SVI II AP input. If 20 mA is not
attainable, troubleshoot the source and set up.
For split range installations the compliance voltage must be
capable of the minimum span being 5 mA; the upper range
value must be 8 mA to 20 mA; the lower range values must
be 4 mA to 14 mA.
For an input current between 4 and 20 mA the voltage varies between
11 V and 9 V respective.
When voltage exceeds 11 V check that polarity is correct.
If voltage is less than 9 V and polarity is correct, voltage compliance of
current source is inadequate.
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Grounding Practices