Electrical Connections; Stroke Port - Emerson Fisher 846 Instruction Manual

Instruction Manual
Form 5739
February 2002
D excessive vibration.
D pressure pulsation.
D excessive instrument
temperature.
D corrosion of the pressure
containing parts.
D other misuse.
Refer to ANSI B40.1-1980. Do not use
on oxygen service.

Electrical Connections

WARNING
Personal injury or property damage
could result from fire or explosion. In
explosive atmospheres, remove power
and shut off the air supply to the I/P
unit before attempting to remove the
terminal compartment cover or
module cover. Failure to do so could
result in an electrical spark or
explosion.
Personal injury or property damage
may occur from an uncontrolled
process. Unscrewing the module
cover removes power from the
electronics and the output signal will
be 0.0 psi. Before removing the
module cover, ensure the process is
properly controlled.
CAUTION
Excessive current can damage the
transducer. Do not connect an input
current of more than 100 mA to the
transducer.
Signal wiring is brought to the terminal compartment
through a 1/2–14 NPT housing conduit connection,
shown in figure 2-1. Where condensate is common,
use a conduit drip leg to help reduce liquid buildup in
the terminal compartment and avoid shorting of the
input signal. Electrical connections are made at the
terminal block. An internal grounding lug is provided
to facilitate a separate ground when required. As
shown in figure 2-4, units with CENELEC
certification also have an external earthing
connection. The use of shielded cable will ensure
proper operation in electrically noisy environments.
Connect the positive signal lead to the positive
terminal, marked +. Connect the negative signal
lead to the negative terminal, marked –.
Units with the Remote Pressure
Reading (RPR) option may cause
interference with the analog output
signal from some instrumentation
systems. This problem may be solved
by placing a 0.2 microfarad capacitor
or a HART filter across the output
terminals.
WARNING
Personal injury or property damage
could result from an uncontrolled
process. Unscrewing the module
cover removes power from the
electronics and the output signal will
be 0.0 psi. Before removing the
module cover, ensure the process is
properly controlled.

Stroke Port

WARNING
Personal injury or property damage
could result from fire or explosion of
accumulated gas. During normal
operation, supply air is vented to the
atmosphere through the stroke port in
the module cover and exhaust port
(located under the nameplate). If a
flammable gas is used as the supply
air, the area into which it is vented
must be classified as a Division I
hazardous area. Adding a remote vent
to the stroke port is not sufficient to
permit safe operation in a hazardous
area.
The constant bleed of supply air from the pilot stage
is directed out the stroke port, which is a screened
hole located at the center of the module cover.
Figure 2-1 shows the location of the stroke port.
Before installing the transducer, ensure the stroke
Installation
Note
2–7