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M9344 • REV K
(April 2022) Page
3 of 8
The maximum loop power supply voltage that may be applied is 30 VDC. The maximum loop
resistance (RL) is calculated by the equation:
RL = 50 (VS - 13)
W
Example: RL = 50 (24 - 13) = 550
W
for 24 VDC loop supply.
2.B EXPLOSION-PROOF INSTALLATION IN HAZARDOUS LOCATIONS
ST5491E transmitters are CSA certified explosion-proof, Class I (C & D); Class II (E, F & G,).
Connect the field wiring in accordance with the appropriate diagram on page 3. Refer to
paragraph 2.A for loop voltage and resistance requirements. All conduit and junction boxes
used must be certified explosion-proof for the class, division and group required by the
application. Installation of the transmitter must meet all of the explosion-proof installation
requirements of the local governing agency and facility safety procedures.
3. ELECTROMAGNETIC COMPATIBILITY
To meet the requirements of electromagnetic compatibility in areas of high electromagnetic
interference, the field wiring must be:
1. Shielded twisted pair cable enclosed in grounded metallic conduit, or
2. Double shielded twisted pair cable with a metallic body cable gland fitting and with the
outer shield grounded.
WIRING DIAGRAMS
Use standard two-conductor, twisted pair, shielded wiring for the long run to the instrumenta
-
tion enclosure. The transmitter is connected like any other loop powered end device.
3.A CONNECTION TO PLC OR OTHER INDICATING INSTRUMENT
The first step in configuring the PLC, DCS, or other recording instrument is to determine the
source of power. The ST5491E requires loop power be supplied to it. Some Analog Input
channels, on a PLC or DCS, for example, provide this power from within. If they do not
provide power, an external power supply must be provided. Connect the transmitter field
wiring using standard instrumentation practices.