en
Description
3.2.2
4 to 20 mA interface
The 4 to 20 mA interface is configured to automatically detect whether the receiver works as sink or source (factory setting).
If the 4 to 20 mA signal line is connected to 0 V (gnd), the receiver automatically works as a source after switching on. If the
4 to 20 mA signal line is connected to supply voltage (Power+), the receiver automatically works as sink after switching on. This
behaviour is configurable. The system can be permanently set to sink or source. In that case, automatic detection is excluded.The
following values for the different states apply for all configurations described.
The 4 to 20 mA interface signals the following states:
Status
Measuring value output
Over range
Under range
Warning
Maintenance
Fault
Beam Block
a) when using the SIL Lock: 0.5 to 3.5 mA
The "Maintenance" state can be triggered by various maintenance functions. The maintenance functions are indicated by blink
patterns of the LEDs. In maintenance mode the gas warning system automatically ends the activated maintenance function after
60 minutes and returns automatically to measuring mode.
The transmitter has no 4 to 20 mA interface. The "Warning" or "Fault" states at the transmitter are forwarded to the receiver if the
DIGITAL LINK connection is installed.
3.3
Intended use
The gas warning system is used for stationary, continuous monitoring of areas where flammable gases and vapours containing
hydrocarbons could occur.
The gas warning system is approved for operation in explosion-hazard areas.
3.4
Limitations on use
The gas warning system is not suitable for monitoring areas where the temperature or pressure deviates from the ambient
conditions specified in Chapter 8 on Page 62.
The gas warning system must not be used in oxygen-enriched atmospheres.
3.5
Approvals
For information on approvals, see supplement 9033710.
3.6
SIL (Safety Integrity Level)
The gas warning system is SIL 2-certified. To ensure SIL-compliant operation, the gas warning system must be protected against
inadvertent or unauthorised changes to the configuration. To do so, SIL LOCK must be activated. Two passwords are available.
For applications with Safety Integrity Level, observe the safety manual (9033709).
44
Factory setting
>3.8 mA ... <20.5 mA
≥20.5 mA
3.8 mA
3.5 mA
3.0 mA
1.0 mA
2.0 mA
Configurable
no
no
no
yes
yes
yes
yes
Configurable range
a)
0.5 to 5 mA
0.5 to 3.2 mA
0.5 to 3.2 mA
0.5 to 3.2 mA