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Installation Manual 21
I/O Wiring – Model 2400S Analog Transmitters
Power Supply I/O Wiring – DP and DNI/O Wiring – ANBefore You Begin
3.5.1 Hazardous area safety
The proper barrier selection will depend on what output is desired, which approval is applicable, and
many installation-specific parameters. The information that is provided about IS barrier selection is
intended as an overview. Refer to barrier manufacturers for more detailed information regarding the
use of their products. Application-specific questions should be addressed to the barrier manufacturer
or to Micro Motion.
Hazardous area voltage
The Model 2400S transmitter’s safety parameters require the selected barrier’s open-circuit voltage to
be limited to less than 36 VDC (V
max
= 36 VDC). This voltage is the combination of the maximum
safety barrier voltage (typically 28 VDC) plus an additional 2 VDC for HART communications when
communicating in the hazardous area.
Hazardous area current
The Model 2400S transmitter’s safety parameters require the selected barrier’s short-circuit currents
to sum to less than 500 mA (I
max
= 500 mA) for the milliamp outputs and 500 mA (I
max
= 500 mA) for
the frequency/discrete output.
Hazardous area capacitance
The capacitance (C
i
) of the Model 2400S transmitter is 1.1 nF. This value added to the wire
capacitance (C
cable
) must be lower than the maximum allowable capacitance (C
a
) specified by the IS
barrier. Use the following equation to calculate the maximum length of the cable between the
transmitter and the barrier:
WARNING
A transmitter that has been improperly wired or installed in a hazardous area
could cause an explosion.
To avoid the risk of an explosion:
• Make sure the transmitter is wired to meet or exceed local code requirements.
• Install the transmitter in an environment that complies with the classification tag
on the transmitter. See Appendix A.
Table 3-3 Safety parameters
Parameter
Value
4–20 mA output Frequency/discrete output
Voltage (U
i
) 36 V 36 V
Current (I
i
) 500 mA 500 mA
Power (P
i
) 1.5 W 1.5 W
Capacitance (C
i
) 1.1 nF 1.1 nF
Inductance (L
i
) 0.0 mH 0.0 mH
C
i
C
cable
C
a
≤+