GE BAKER HUGHES Masoneilan SVi 1000, Быстрый старт

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Masoneilan SVi1000 Positioner Quick Start Guide =
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Wiring Guidelines
Guidelines for a successful implementation of DC current signal, DC power, and HART
®
commu-
nication to the SVi1000:
Compliance voltage at the SVi1000 is approximately 9 V at the current of 20
mA. “Determining an SVI Positioner Compliance Voltage in a Control System”
on page
63.
Signal to the SVi1000 must be a regulated current in the range 3.2 to 22 mA.
Controller output circuit must be unaffected by the HART
®
tones which are
in the frequency range between 1200 and 2200 Hz.
In the frequency range of the HART
®
tones, the controller must have a circuit
impedance of more than 220 Ohms, typically 250 Ohms.
HART
®
tones may be imposed by the positioner and a communication
device located anywhere on the signaling circuit.
Cabling must be shielded to prevent electrical noise that would interfere with
the HART
®
tones, with the shield grounded.
Shield must be properly grounded in only one place.
For details and calculation methods for wiring resistance, and capacitance
and for calculation of cable characteristics, refer to the HART
®
FSK Physical
Layer Specification.
For split range installations the output voltage must be sufficient to operate
two positioners (11 V @ 4 mA, 9 V @ 20 mA) and the expected voltage drop in
the cable.
Use of a low impedance voltage source damages the SVi1000. The current
source must be a true high impedance current limiting device. A proper
current source explicitly enables adjustment of the current, not the voltage.
Position Retransmit: when wiring this feature:
Use the same gauge wires as the 4-20 mA control loop.
Ensure that the position retransmit signal is connected to the control
system’s analog input card.
Ensure the control loop is powered while making measurements with a
meter.
WARNING
This process can cause the valve to move. Before proceeding be
sure the valve is isolated from the process. Keep hands clear from
moving parts.