Rockwell Automation 1797-IRT8 FLEX Ex Thermocouple/RTD/mV Input Module User Manual - Manual (Page 60)

Publication 1797-6.5.2 - February 2001
6-6 Applying FLEX Ex Thermocouple/RTD/mV Input Modules
Entity Parameters
Entity parameters are a system of quantified safe levels for voltage,
current, inductance, and capacitance used when connecting multiple
devices.
The following table details the entity parameters that must be taken
into account when designing a FLEX Ex system.
In the table above, power sources are devices such as outputs or
inputs, and power receivers are devices such as transmitters.
In use, the sum of all the input internal capacitance (C
i
) or internal
inductance (L
i
) in a control loop cannot exceed the allowed
capacitance (C
o
) or allowed inductance (L
o
).
Also, the open-circuit voltage (U
o
) or short circuit current (I
o
) cannot
exceed the maximum input voltage (U
i
) or maximum input current
(I
i
).
Table 6.B
Entity Terms: Applied to: CENELEC FM/CSA
Maximum output (open-circuit) voltage Power sources U
o
V
oc
Maximum output (short circuit) current Power sources I
o
I
sc
Maximum allowed capacitance Power sources C
o
C
a
Maximum allowed inductance Power sources L
o
L
a
Maximum input voltage Power receivers U
i
V
max
Maximum input current Power receivers I
i
I
max
Maximum internal capacitance Power receivers C
i
C
I
Maximum internal inductance Power receivers L
i
L
I