1 As provided for by Section
3.1 of these Guidelines, in the case of the E2/E3/D2 test cycles,
the minimum number of load points should be such that the combined
nominal weighting factors as given in the NOx Technical Code, paragraph 3.2, are greater than 0.50.
2 Consequently, for the E2/E3 test cycle it would
be necessary to use the 75% load point plus one or more other load
points. In the case of the D2 test cycle, either the 25% or 50% load
point should be used plus either one or more load points such that
the combined nominal weighting factor is greater than 0.50.
3 The examples below give some of the possible
combinations of load points which may be used together with the respective
revised weighting factors:
|
E2/E3 test cycles
|
| Power
|
100%
|
75%
|
50%
|
25%
|
| Nominal weighting factor
|
0.2
|
0.5
|
0.15
|
0.15
|
| Option A
|
0.29
|
0.71
|
|
|
| Option B
|
|
0.77
|
0.23
|
|
| Option C
|
0.24
|
0.59
|
|
0.18
|
| Plus
other combinations which result in a combined nominal weighting factor
greater than 0.50. Hence use of the 100% + 50% + 25% load points would be
insufficient.
|
|
D2 test cycle
|
| Power
|
100%
|
75%
|
50%
|
25%
|
10%
|
| Nominal weighting factor
|
0.05
|
0.25
|
0.3
|
0.3
|
0.1
|
| Option D
|
|
|
0.5
|
0.5
|
|
| Option E
|
|
0.45
|
|
0.55
|
|
| Option F
|
|
0.38
|
0.46
|
|
0.15
|
| Option G
|
0.06
|
0.28
|
0.33
|
0.33
|
|
| Plus other combinations which result in a combined
nominal weighting factor greater than 0.50. Hence use of the 100% + 50% +
10% load points would be insufficient.
|
4 In the case of the C1 test cycle, as a minimum,
one load point from each of the rated, intermediate and idle speed
sections should be used. The examples below give some of the possible
combinations of load points which may be used together with the respective
revised weighting factors:
|
C1 test cycle
|
| Speed
|
Rated
|
Intermediate
|
Idle
|
| Torque
|
100%
|
75%
|
50%
|
10%
|
100%
|
75%
|
50%
|
0%
|
| Nominal weighting factor
|
0.15
|
0.15
|
0.15
|
0.1
|
0.1
|
0.1
|
0.1
|
0.15
|
| Option H
|
|
0.38
|
|
|
0.25
|
|
|
0.38
|
| Option I
|
|
|
|
0.29
|
|
0.29
|
|
0.43
|
| Option J
|
0.27
|
0.27
|
|
|
|
|
0.18
|
0.27
|
| Option K
|
0.19
|
0.19
|
0.19
|
0.13
|
|
0.13
|
|
0.19
|
| Plus
other combinations incorporating at least one load point at each of rated,
intermediate and idle speeds
|
5 Examples of calculation of revised weighting
factors:
| For Option A:
|
| 75% load: revised value is calculated
as: 0.5 x (1/(0.5 + 0.2)) = 0.71
|
| 50% load: revised value is calculated
as: 0.2 x (1/(0.5 + 0.2)) = 0.29
|
|
|
| For Option F:
|
| 75% load: revised value is calculated
as: 0.25 x (1/(0.05 + 0.25 + 0.3 + 0.3)) = 0.38
|
Note The revised weighting factors are shown to 2 decimal places.
However, the values to be applied to NOx Technical Code equation 18
should be to the full precision. Hence in the Option F case above
the revised weighting factor is shown as 0.38 although the actual
calculated value is 0.384615...
Consequently, in these examples of revised weighting factors
the summation of the values shown (to 2 decimal places) may not sum
to 1.00 due to rounding.