Rockwell Automation 1797-IRT8 FLEX Ex Thermocouple/RTD/mV Input Module User Manual - Manual (Page 63)

Publication 1797-6.5.2 - February 2001
Applying FLEX Ex Thermocouple/RTD/mV Input Modules 6-9
Each power supply output in the FLEX Ex system is rated for 8.5W.
Modules can be attached to the output until their combined power
equals that number. Do not exceed the power supply maximum of
8.5W.
Assign the next module to another output as before. When all four
power supply outputs are utilized, add another power supply to the
system, see the figure below.
Power Supply Considerations
When applying power, consider the certain characteristics of the wire
connecting the power supply output to a module’s power input. The
wire cannot exhibit more than:
•
0.1
Ω
of resistance (+V and -V combined)
•
800nF of capacitance
•
10mF of inductance
Typically, these restrictions will yield wiring lengths of not more than
3.5m or 5.8m (1.5mm
2
and 2.5mm
2
wire respectively) without the use
of special wiring or wiring methods.
IS Pwr
Safe Area
Hazardous Area
1797 power supply
1797 power supply
1797 power supply
ACNR Spare IE8 OE8 IRT8 Spare Spare IJ2 IJ2
ACNR OB4D OB4D IBN16 IBN16 IBN16 IE8 IRT8 OE8
RPA RPFM RPFM
IS 1797 I/O
IS 1797 I/O
IS 1797 Fiber Hub
IS Pwr
IS Pwr
IS Pwr
IS Pwr
IS Pwr
IS Pwr
IS Pwr
IS Pwr
IS Pwr
IS Pwr
IS Pwr
EEx d
/e
EEx ib
EEx d
/e
EEx ib
EEx d
/e
EEx ib
41306
Unsafe
Power
Entrance
Spare