Establishing Communications; Figure 19 Typical Sfc Connections - Honeywell ST 3000 User Manual

5.2

Establishing Communications

SFC connection rules
Connecting SFC
WARNING
Figure 19 Typical SFC Connections.
+
Power
Supply
-
Receiver
250 
50 ST 3000 Release 300 and SFC Model STS103 User's Manual
 Always plug the SFC leads into the jack on the SFC before you
connect them to the transmitter.
 Use this formula to find the maximum filter capacitance allowed
across the sense resistor (250 ohm minimum) for SFC
communications to work.
C (µF) = 1000 / R
Using either leads with alligator clips or easy-hooks supplied with the
SFC, you connect the SFC directly to signal terminals on the
transmitter's terminal block or at any convenient location in the 4 to 20
milliampere line. Observing polarity, connect the red lead to positive (+)
and the black lead to negative (–).
When the transmitter's end-cap is removed, the housing is not
explosionproof.
Figure 19 shows typical SFC connections across loop wiring to the
ST 3000 transmitter. (Non-lightning protection terminal connections
shown.)
+
-
Field
Terminals
SFC
sense
+ Red
- Black
ST 3000
STR3012
Continued on next page
February 2012