Functional monitoring of an electrolytic gas sensor having three electrodes, and hazard alarm and gas measuring device

摘要

An electrolytic gas sensor which is sensitive to a specific gas and has a working, reference and counter electrode is functionally monitored. A differential voltage between the reference and working electrodes is amplified and the potential of the counter electrode is regulated to minimize the differential voltage. Then a measured current flowing into the counter electrode approximately proportionally to the gas concentration of the gas to be detected arises. Independently of the determination of the gas concentration, a working, counter and reference voltage which is present at the three electrodes in each case is captured and monitored for an impermissible deviation. In an impermissible case an assigned error message is then output. Online monitoring of the gas sensor is thus possible and no interruption of the measurement operation for test purposes and additional components are required.

主权项

1. A method for the functional monitoring of an electrolytic gas sensor that is sensitive to a specific gas, the gas sensor having a working electrode, a reference electrode, and a counter electrode, the method comprising:
amplifying a differential voltage present between the reference and working electrodes and regulating the differential voltage on a basis of a potential of the counter electrode such that the differential voltage becomes as small as possible, whereupon a measured current arises which flows into the counter electrode and is approximately proportional to a gas concentration of the gas to be detected; converting the measured current into a measured voltage proportional thereto, wherein then the measured voltage represents the gas concentration approximately proportional thereto; and independently of a determination of the measured current representing the gas concentration, capturing a working voltage present at the working electrode, a counter voltage present at the counter electrode, and a reference voltage present at the reference electrode and monitoring the voltages for an impermissible deviation; when an impermissible deviation is detected, outputting an assigned error message; and monitoring at least one combination of the measurement voltage, the working voltage, the counter voltage and the reference voltage for another impermissible deviation and, in an impermissible case, outputting an assigned further error message.