17 Appendix

Pl =

+ 0.25 C

(accuracy of standardisation )

Pz =

+ 0.25 C

(zero accuracy )

Pd =

0

(no zero offset)

Pm calculation :

Slope calculation at 240C : 321 + (301-321) x (240-200) / (400-200) so 317 V/C Pm = 210 / 317 = + 0.66C

Max. total accuracy:

Pt = + 0.25 + 0.25 + 0.66 = + 1.16C

17.4. Accuracy class index of class

This is one of the essential concepts of the C.E.I. recommendation: it is intended to alleviate the listing of the specifications. In order to do so, it introduces the concept of ACCURACY CLASS, which is determined here as CLASS C INDEX.

The normalised values of the index of class are: C = 0.1 ; 0.25 ; 0.5 and 1.

The intrinsic error (in the reference conditions) does not exceed C % (the manufacturer can also specify this limit of the intrinsic error as an absolute value (for example 5 microvolts) for the first ranges).

When one of the influence variable varies within the nominal range of use, variations (of the measured value) do not exceed:

-C % for the position, for the magnetic induction from outer origin and for spurious voltages

-0.5 C% for the power supply

-0.3 C% according to the class index for the room temperature (0.15 % for the 0.25 class).

Moreover, the range of insensitivity must not exceed:

-C% in the reference conditions

-1.5 C% for the maximum resistance of the outer circuit of measure

-2 C% for the spurious voltages

-

Eventually, no overvalue should exceed 2 C% (4 C% for the limits of the power supply).

Page 8

Page 137
Image 137
Escort 3004B, 3016B, 3008B user manual Accuracy class index of class