Division 7.8.2.4 Validation criteria
United Kingdom
RMC tests shall be validated using the regression analysis as described in points 7.8.3.3 and 7.8.3.5. The allowed RMC tolerances are given in the following Table 6.1. Note that the RMC tolerances are different from the NRTC tolerances of Table 6.2. F1When conducting testing of engines of reference power greater than 560 kW the regression line tolerances of Table 6.2 and the point deletion of Table 6.3 may be used.
Table 6.1
RMC Regression line tolerances
| Speed | Torque | Power | |
|---|---|---|---|
| Standard error of estimate (SEE) of y on x | maximum 1 % of rated speed | maximum 2 % of maximum engine torque | maximum 2 % of maximum engine power |
| Slope of the regression line, a 1 | 0,99 to 1,01 | 0,98 - 1,02 | 0,98 - 1,02 |
| Coefficient of determination, r 2 | minimum 0,990 | minimum 0,950 | minimum 0,950 |
| y intercept of the regression line, a 0 | ± 1 % of rated speed | ± 20 Nm or 2 % of maximum torque whichever is greater | ± 4 kW or 2 % of maximum power whichever is greater |
In case of running the RMC test not on a transient test bed, where the second by second speed and torque values are not available, the following validation criteria shall be used.
At each mode the requirements for the speed and torque tolerances are given in point 7.8.1.3. For the 20 s linear speed and linear torque transitions between the RMC steady-state test modes (point 7.4.1.2) the following tolerances for speed and load shall be applied for the ramp:
- (a)
the speed shall be held linear within ± 2 % of rated speed,
- (b)
the torque shall be held linear within ± 5 % of the maximum torque at rated speed.