Division 3 Measurements and determination of the efficiency
United Kingdom
The efficiency of the 12 V motor generator shall be determined in accordance with ISO 8854:2012, with the exception of the elements specified in this point.
Evidence shall be provided to the type approval authority that the speed ranges of the efficient 12 V motor generator are consistent with those set out in Table 1. The measurements shall be conducted at different operating points, as set out in Table 1. The efficient 12 V motor generator current intensity shall be defined as half of the rated current for all operating points. For each speed the voltage and the output current of the alternator shall be kept constant at 14,3 V.
Table 1
Operating points
| Operating pointi | Holding time[s] | Rotational frequencyni[min– 1] | Frequencyhi |
|---|---|---|---|
| 1 | 1 200 | 1 800 | 0,25 |
| 2 | 1 200 | 3 000 | 0,40 |
| 3 | 600 | 6 000 | 0,25 |
| 4 | 300 | 10 000 | 0,10 |
The efficiency at each operating point shall be calculated in accordance with the following Formula 1: