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6-6
Applying FLEX Ex Thermocouple/RTD/mV Input Modules
Table 6.B
Entity Terms:
Maximum output (open-circuit) voltage
Maximum output (short circuit) current
Maximum allowed capacitance
Maximum allowed inductance
Maximum input voltage
Maximum input current
Maximum internal capacitance
Maximum internal inductance
Publication 1797-6.5.2 - February 2001
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.
Applied to:
Power sources
Power sources
Power sources
Power sources
Power receivers
Power receivers
Power receivers
Power receivers
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
inductance (L
) in a control loop cannot exceed the allowed
i
capacitance (C
) or allowed inductance (L
o
Also, the open-circuit voltage (U
exceed the maximum input voltage (U
(I
).
i
CENELEC
FM/CSA
U
V
o
oc
I
I
o
sc
C
C
o
a
L
L
o
a
U
V
i
max
I
I
i
max
C
C
i
I
L
L
i
I
i
).
o
) or short circuit current (I
o
) or maximum input current
i
) or internal
) cannot
o
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