A case study of power quality metering for short-term disturbance analysis

Generators tied to an electric utility´s power lines can be susceptible to power quality events that occur on the grid. This paper describes an example of the damaging effects that lightning can have on cogeneration equipment. Permanently mounted electronic monitoring equipment provided disturbance data that was used to determine the cause of the damage to the generator. This information made it possible to observe line-to-ground faults, sudden changes in phase currents and oscillations in phase voltage or current. Four-quadrant metering and accurate time-stamping of power quality events provided the information needed to determine the sequence of events in a forensic analysis of the disturbance leading to the damage.