Table 2.

Overview of the oil condition parameters to be monitored and the corresponding optical bandpass filters selected for the implementation of the NDIR sensor. FWHM: full width at half maximum.

Spectral Feature	Target ${\tilde{\mathit{\nu }}}_{\mathbf{\Theta }}$ (cm${}^{-1}$)	Target ${\tilde{\mathit{\nu }}}_{\perp }$ (cm${}^{-1}$)	Commercial Filter ${\tilde{\mathit{\nu }}}_{\perp }$/FWHM (cm${}^{-1}$)
Baseline point 1	3900	3881	3876/75
Water content	3409	3393	3390/57
Baseline point 2	2100	2090	2119/40
Oxidation and AN influence	1710	1702	1729/27
AN influence	1606	1598	1608/36
AN influence	1162	1156	1151/27
AN influence	1040	1035	n. a.
AN influence	987	982	980/9
AN influence	722	718	n. a.