Partial discharge measuring and/or fault location in HV insulation - using pulse-echo method by charging capacitor, triggering, decoupling, processing and displaying before point of application

Calibration is achieved by coupling pulses of defined charge in the test piece, e.g. plastics insulated h.v. cable or electrical installation. The triggering of the partial discharges follows through discharge of the capacitor in the test piece with a decoupling unit switched in parallel. The capacitor (7) is only charged to a certain stipulated voltage through a controlled recharge blocking unit (1). The controlled discharge of the capacitor follows via a discharge impedance (11) matched to the test piece and an alternating impedance (12) such that a certain pulse form appears across the test piece. A measuring window signal (MF) is formed from a voltage (U2) proportional to this pulse after a threshold value has been attained. USE/ADVANTAGE - Prophylactic fault location in insulation of h.v. cables and electrical installations. Application for laboratory testing or in the field since no n.v. generator is required and method can use modular equipment for easy demounting and transporting.