Grounding - ABB Platinum standard Series Product Instruction

INSTALLATION
SETUP AND PHYSICAL INSTALLATION
3 - 16
In the digital mode, the process variable signal of each trans-
mitter is a digitally polled variable. The field bus module
sequentially polls each transmitter output on the bus. Each
transmitter on the bus has its own unique address that is
assigned during configuration. Refer to
Section 5 for information on configuring the transmitter
address. The address allows the field bus module to distin-
guish between transmitters on the loop.
Each transmitter present on the bus is wired from the control
system to the + (positive) and - (negative) terminals of the
transmitter. Connect all transmitters on the bus in parallel.
The minimum power supply voltage required for the loop is
determined by:
minumum supply voltage =
( ×
12 volts 0.004 no. of transmitters on bus
+
The load resistance must include the system input resistance
and the resistance of the wire. No meters or measuring devices
are to be included in the field bus loop since the transmitters
are not delivering an analog process variable. Power supply
regulation is not critical as long as the voltage remains above
the minimum calculated value.
The Type STT terminal can be connected anywhere there is
access to the signal leads. Since the Type STT terminal also
has its own bus address, it can be connected to the bus while
the control system is online. Only one Type STT terminal can
be connected to the bus at any one time. While the field bus
module is online, the Type STT terminal can monitor any
transmitter on the bus.
In order to change any calibration or configuration parameters
of transmitters using the Type STT terminal, the field bus
module must be instructed to bring the desired transmitter
offline.
Signal wiring should not be run in conduit or open trays with
wiring used to power other devices and should not be run near
heavy electrical equipment. Twisted shielded pairs are recom-
mended for best results. Reverse polarity protection is built
into the transmitter to protect it against accidental reversal of
the field wiring connections.

GROUNDING

Signal wiring may be either ungrounded (floating) or grounded
at any one point in the signal loop. If more than one transmit-
ter is connected to a single power supply, grounding should be
at the supply. The transmitter housing must also be grounded.
Channel Number in
× )
load resistance
WBPEEUI110504A0