A load dump in a vehicle can occur when a load is suddenly dropped while another high-voltage (HV) component—particularly the powertrain or a charging component—continues to supply energy to the HV electrical system. This can cause a transient rise in the HV electrical system voltage, typically resulting in an overvoltage that must not exceed a specified limit.

For this reason, the components must be tested individually to assess their behavior during load shedding.

The load shedding test in accordance with ISO 21498 evaluates the maximum voltage dynamics and peak voltage that occur, as well as the component’s ability to limit them.

To do this, the load dump box is connected to the high-voltage circuit between the voltage source and the device under test. Once the component’s operating point has been established, the high-voltage circuit is abruptly interrupted by the load dump box. According to ISO 21498 and MBN 11123, MBN 51123, this must occur in less than 100 µs. This time value is used to ensure the comparability of test results.