Emerson Process Management IM-106-340 General Alarm Indications, Grounding, Electrical Noise

Instruction Manual

IM-106-340, Rev. 4.0 May 2006

Oxymitter 4000

GENERAL

ALARM INDICATIONS

Install all protective equipment covers and safety ground leads after troubleshooting. Failure to install covers and ground leads could result in serious injury or death.

The troubleshooting section describes how to identify and isolate faults that may develop in the Oxymitter 4000. When troubleshooting, reference the following.

Grounding

It is essential that adequate grounding precautions are taken when installing the system. Thoroughly check both the probe and electronics to ensure the grounding quality has not degraded during fault finding. The system provides facilities for 100% effective grounding and the total elimination of ground loops.

Electrical Noise

The Oxymitter 4000 has been designed to operate in the type of environment normally found in a boiler room or control room. Noise suppression circuits are employed on all field terminations and main inputs. When fault finding, evaluate the electrical noise being generated in the immediate circuitry of a faulty system. Ensure all cable shields are connected to earth.

Loose Integrated Circuits

The Oxymitter 4000 uses a microprocessor and supporting integrated circuits (IC). If the electronics are handled roughly during installation or located where subjected to severe vibration, the ICs could work loose. Before troubleshoot- ing the system, ensure all ICs are fully seated.

Electrostatic Discharge

Electrostatic discharge can damage the ICs used in the electronics. Before removing or handling the processor board or the ICs, ensure you are at ground potential.

The first indication of a problem at the analyzer usually comes from the Oper- ators running the process. Critical alarms that render the O2 measurement unusable will force the 4-20 mA analog output signal representing O2 to go to a default condition, as follows:

4-20 mA Signal Alarm Levels

4-20 mA signal	Analyzer Condition
0 mA	Analyzer unpowered, or completely failed
3.5 mA	Critical Alarm - analyzer reading unusable (factory default)
3.8 mA	Reading Under Range (Example - user sets range to 2-10%. Current
	reading is 1.9%)
4 to 20 mA	Normal Operation
20.5 mA	Reading Over Range (Example - range is 0-10%. Current reading is 12%)
>21 mA	Critical Alarm - analyzer reading is unuasble (user can choose this alarm
	level instead of the factory default level of 3.5 to 3.6 mA)

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