Sierra Monitor Corporation 5000 instruction manual Cover Plate Oxygen Module

SMC sierra monitor corporation Sentry Instruction Manual - Version 6

7.6 OXYGEN MODULE (5100-03)

7.6.1 DESCRIPTION

The Oxygen Module includes the electronic assembly installed in an explosion proof housing and the electrochemical sensor connected to one hub of the enclosure. Cabling from the controller connects to a three pin spring loaded terminal strip.

7.6.2 TROUBLE ANALYSIS

Electrical adjustment, or replacement of the sensor will be necessary under the following conditions:

•Controller displays the following error messages:

CHANGE SENSOR

SENSOR FAILURE

REPLACE SENSOR

•False readings or alarms are received due to sensor inaccuracy.

Warning: During	sensor	adjustments	the
concentration reading on the controller will be
inaccurate and alarm level concentrations may be				Figure 7-7
displayed. If false activation of the alarm relays				Cover Plate - Oxygen Module
will cause a problem disconnect the relay wiring
prior to adjustment or turn the module off using

the "Change Module" mode.

			7.6.4 SENSOR REPLACEMENT
	NOTE		The oxygen sensor should be replaced when it can no
	Although all the necessary data can be collected with a
	voltmeter at the sensor module, some helpful information		longer be calibrated correctly or when the signal output
	can be displayed on the controller or printed. See		drops to zero. Generally this is every twelve to eighteen
	diagnostic codes 0004 and 0008 in Appendix C.		months. The Sentry clock keeps track of the age of the
7.6.3 ADJUSTMENT PROCEDURE			sensor if it is correctly initialized in the "change module"
			mode.
Prior to reading voltages and making adjustments perform
			When a new sensor is installed use the CHANGE MODULE
a visual inspection to confirm that there are no physical
			menu selection to	answer yes	to	the "new	sensor?"
problems such as water in the electronics enclosure,
			question. After	nine months	the	CHANGE	SENSOR
wiring damage or corrosion.
			message will be displayed to warn that a new sensor
Use Figure 7-7 to locate test points during the following
			should be installed.
procedures.			The SENSOR FAILURE message for Oxygen sensors does
7.6.3.1 SIGNAL ADJUSTMENT			not indicate a specific failure of the sensor but indicates
			that the sensor is not correctly connected to the
It is unlikely that any electrical adjustment will be			electronics. If this message appears check that the sensor
required except when a new sensor is installed.			harness is correctly installed to the connector on the
To make the electrical adjustment connect a voltmeter to			bottom electronics board.
			When sensor replacement is required, open the cover of
SIGNAL OUT (pos) and GND (ground) and use
SENSITIVITY ADJ potentiometer to set the voltage equal to			the sensor module, remove the transmitter and disconnect
1/10 of the actual oxygen concentration. In clean air the			the sensor wiring harness from the back of the transmitter.
concentration is 20.9% so the voltage should be set at
2.09 VDC.
		SERVICE
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