Document ID: chunk:federal_register_of_legislation:F2025L00028:reg:3:p6
Version: federal_register_of_legislation:F2025L00028
Segment Type: reg
Provision Reference: reg 3 (pt 6/11)
Character Range: 135340–138282

1. Test setup and equipment

              If a high voltage disconnect function is used, measurements are to be taken from both sides of the device performing the disconnect function.

              However, if the high voltage disconnect is integral to the REESS or the energy conversion system and the high-voltage bus of the REESS or the energy conversion system is protected according to protection degree IPXXB following the impact test, measurements may only be taken between the device performing the disconnect function and the electrical loads.

              The voltmeter used in this test shall measure DC values and have an internal resistance of at least 10 MΩ.

              2. The following instructions may be used if voltage is measured.

              After the impact test, determine the high voltage bus voltages (Ub, U1, U2) (see Figure 1 below).

              The voltage measurement shall be made not earlier than 10 seconds, but, not later than 60 seconds after the impact.

              This procedure is not applicable if the test is performed under the condition where the electric power train is not energized.

       Figure 1
       Measurement of Ub, U1, U2

       3. Assessment procedure for low electrical energy

               Prior to the impact a switch S1 and a known discharge resistor Re is connected in parallel to the relevant capacitance (ref. Figure 2 below).

                  (a) Not earlier than 10 seconds and not later than 60 seconds after the impact the switch S1 shall be closed while the voltage Ub and the current Ie are measured and recorded. The product of the voltage Ub and the current Ie shall be integrated over the period of time, starting from the moment when the switch S1 is closed (tc) until the voltage Ub  falls below the high voltage threshold of 60 V DC (th). The resulting integration equals the Total Energy (TE) in joules.

                  (b) When Ub is measured at a point in time between 10 seconds and
                  60 seconds after the impact and the capacitance of the X-capacitors (Cx) is specified by the manufacturer, Total Energy (TE) shall be calculated according to the following formula:

                 TE = 0.5 x Cx x Ub2

                  (c) When U1 and U2 (see Figure 1 above) are measured at a point in time between 10 seconds and 60 seconds after the impact and the capacitances of the Y-capacitors (Cy1, Cy2) are specified by the manufacturer, Total Energy (TEy1, TEy2) shall be calculated according to the following formulas:

                   TEy1 = 0.5 x Cy1 x U12

                      TEy2 = 0.5 x Cy2 x U22

                  This procedure is not applicable if the test is performed under the condition where the electric power train is not energized.

       Figure 2
       E.g. measurement of high voltage bus energy stored in X-capacitors

              4. Physical protection

              Following the vehicle