Emerson 2400S Manuel D’Utilisation

21

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.

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.

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.

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: 

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.

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

≤

+