Division 2.1 48V motor-generator efficiency
United Kingdom
The efficiency of the 48V motor-generator shall be determined in accordance with ISO 8854:2012, with the following precisions.
The manufacturer shall provide evidence to the type-approval authority that the frequency ranges of the 48V motor-generator are the same as or equivalent to those set out in Table 1.
The efficiency of the 48V motor-generator shall be determined on the basis of measurements at each of the operating points listed in Table 1.
The current intensity of the 48V motor-generator at each operating point shall be half the rated current. For each operating point, the voltage and the output current of the 48V motor-generator shall be kept constant during the measurement, with the voltage at 52V.
Table 1
| Operating pointi | Holding time[s] | Rotational frequency | Frequency of operating points |
|---|---|---|---|
| 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 of the 48V motor-generator at each operating point i ( 
Formula 1
where, for each operating point i,
is the voltage [V];
is the current intensity [A];
is the torque [Nm];
is the rotational frequency [min-1].
For each operating point, the measurements are to be performed at least five times consecutively and the efficiency shall be calculated for each of those measurements 
For each operating point, the average of those efficiencies 
The efficiency of the 48V motor-generator 
Formula 2
where
is the mean efficiency of the 48V motor-generator determined for operating point i [%]
is the frequency of operating point i, as set out in Table 1.