Quick Reference for End-Users Lambda Transmitter LT2 ... - lamtec

8 Service and MaintenanceCAUTION!Which instrument measures correctly?Compensation should only be carried out if it was previously ascertained, e.g. by using testgases, that the comparison instrument is measuring correctly.8.2 Checking the LT28.2.1 Checking the LT2's Measuring InputConnect a digital voltmeter between terminals 33 (-) and 34 (+), in parallel to the probe. Comparethe measured voltage with the probe voltage displayed (U S ).Range: -20 mV … +300 mV.If the difference is less than 1 mV, the LT2 is operating correctly.If the difference exceeds 1 mV, repeat the above step with another digital voltmeter.CAUTION!Check the accuracy of the digital voltmeter used.If the difference persists → exchange the instrument.8.2.2 Checking the Probe's Internal Resistance Measurement8.3 ServicingOnly possible with an LS2 probe simulator, type 655 R 1030.Connect the probe simulator between terminals 33 (-) and 34 (+).With a potentiometer, set an internal resistance < 200Use a voltmeter as follows to check the internal resistance:Measure AC voltage between terminals 33 (-) and 34 (+).The displayed value in mV corresponds to about one half of the probe's internal resistance.If R > 200 , the following warning is output after 10 seconds:"LS2 internal resistance too high”.If R > 300 , the following fault message is output:"Probe wire break / probe faulty”.Example: 150 75 mV.8.3.1 ConsumableCheck the measurement system on a monthly, quarterly or semi-annual basis, depending onthe application.LS2 Lambda probe Mean lifetime 2-3 years (depending on fuel).42