An electrical measurement apparatus may include a bias voltage generator configured to generate and output a bias voltage, a bias probe coupled to the output of bias voltage generator configured to apply voltage bias to a first portion of an external circuit which may be subjected to environmental stresses such as vibration, temperature, humidity etc., a measurement probe configured to receive a second electrical signal from a second portion of the external circuit, and a control unit configured to control the bias voltage generator to generate different bias voltages, patterns, AC/DC etc., receive the second electrical signal from the measurement probe and cause the device to output a response in the second electrical signal to the time-domain discontinuity in the first electrical signal.