| 摘要 |
PROBLEM TO BE SOLVED: To set the operation temperature of a measuring sensor in an accurate adjusted state by calculating the AC current internal resistance of the electrode lead wire of a Nernst measuring cell and calculating operation temperature in consideration of this current AC curent internal resistance. SOLUTION: A measuring sensor 10 is heated for a short time through a heating device 50 at the times of start and re-start. During this heating phase period, the AC current restance Ri of a Nernst measuring cell 12 is measured by a measuring circuit 58 according to a known method. By substracting the sum of known resistors R1-R3 from this resistance Ri, the current AC current internal resistance RZ=R4+R5 of the lead wire of the Nernst measuring cell 12 is calculated. Herein, R1-R3 are generated from the AC current internal resistances of a solid electrolyte 20 and electrodes 16, 18 and R4 (R5) is generated from the AC current internal resistance of the lead wire to an electrode 16 (18)-connection terminal 34 (36). Therefore, when operation temp. is calculated, by considering the current AC current internal resistor RZ of the lead wire, the variation prescribed by the production of a resistance value is removed and the measuring sensor can be operated at accurate operation temp. |
