Siemens Sitrans Certificates and Approvals, NAMUR recommendation NE, Application, Specifications

Certificates and Approvals

The Intrinsic Safety Specifications of the SITRANS LC 500 have been defined and approved as follows:

Application	Specifications
current loop insulated from the measuring circuit	3.6-22 mA
internal capacitance	can be ignored
internal inductance	10 µH
maximum supply voltage	30 Vdc
maximum current	200 mA
maximum power consumption	1.5 W

The SITRANS LC 500 can be directly connected to an intrinsically safe supply for intrinsically safe applications. For non-intrinsically safe operations, such as explosion proof, a safety barrier must be used.

The operation of the SITRANS LC 500 conforms to the following:

NAMUR recommendation NE 43

This recommendation describes rules by which analog transmitters transfer their information to DCS equipment. This information can be divided into two types:

•measurement information

For measurement information the current signal should be within the range of 3.8 to 20.5 mA.

•failure signalling

For failure information which indicates a failure in the measuring system1 the current signal should be in the range of either 0 to 3.6 mA, or 21 mA or greater.

The application will determine which of these two ranges is more desirable. The SITRANS LC 500 can be set for 3.6 mA, or 22 mA, as required2.

Appendix F

1.It may also signal a process level outside the Upper and Lower Sensor Limits, if the unit has been programmed for this. For more information, see Fault Signalling on page 15.

2.See Analog Fault Signalling (2-state) on page 66 for details.

7ML19985GE01 SITRANS LC 500 – INSTRUCTION MANUAL Page 107