Emerson 1700 Benutzerhandbuch

38

The Model 1700 or 2700 transmitter’s safety parameters require the selected barrier’s open-circuit 
voltage to be limited to less than 30 VDC (Vmax = 30 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 1700 or 2700 transmitter’s safety parameters require the selected barrier’s short-circuit 
currents to sum to less than 300 mA (Imax = 300 mA) for the milliamp outputs and 100 mA 
(Imax = 100 mA) for the frequency/discrete output.

The capacitance (Ci) of the Model 1700 or 2700 transmitter is 0.0005 

μF. This value added to the 

wire capacitance (Ccable) must be lower than the maximum allowable capacitance (Ca) specified by 
the I.S. barrier. Use the following equation to calculate the maximum length of the cable between the 
transmitter and the barrier:

≤ Ca

The inductance (Li) of the Model 1700 or 2700 transmitter is 0.0 mH. This value plus the field wiring 
inductance (Lcable), must be lower than the maximum allowable inductance (La) specified by the I.S. 
barrier. The following equation can then be used to calculate the maximum cable length between the 
transmitter and the barrier:

≤ La

To reduce 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

)

30 V

30 V

Current (I

i

)

300 mA

100 mA

Power (P

i

)

1.0 W

0.75 W

Capacitance (C

i

)

0.0005 

μF

0.0005 

μF

Inductance (L

i

)

0.0 mH

0.0 mH