Emerson 2400S 3.5.1Hazardous area safety, 3 Safety parameters, Hazardous area voltage

I/O Wiring – Model 2400S Analog Transmitters

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.

Before You Begin

3.5.1Hazardous 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.

Table 3-3Safety parameters

		Value
Parameter	4–20 mA output	Frequency/discrete output
Voltage (Ui)	36 V	36 V
Current (Ii)	500 mA	500 mA
Power (Pi)	1.5 W	1.5 W
Capacitance (Ci)	1.1 nF	1.1 nF
Inductance (Li)	0.0 mH	0.0 mH

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 (Vmax = 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 (Imax = 500 mA) for the milliamp outputs and 500 mA (Imax = 500 mA) for the frequency/discrete output.

Hazardous area capacitance

The capacitance (Ci) of the Model 2400S transmitter is 1.1 nF. This value added to the wire

capacitance (Ccable) must be lower than the maximum allowable capacitance (Ca) specified by the IS barrier. Use the following equation to calculate the maximum length of the cable between the

transmitter and the barrier:

Ci + Ccable ≤ Ca

Power Supply

I/O Wiring – AN

I/O Wiring – DP and DN

Installation Manual 21