To take action on weak insulations quickly, the failure location must be known. Upcoming insulation defects already produce measurable partial discharges (PD). These partial discharges emit electrical impulses and acoustic signals at the same time.
The PDL 650 measures acoustic signals with multiple sensors spread over the transformer. Then the software determines the failure location using the time difference of all incoming signals. Finally, these coordinates are shown in a 3D model of the transformer.