Critical Load Protection from Transient Surges

Transients in electrical power systems at many installations are found to cause malfunctions in and damage to electronic equipment. Investigations to date indicate that harmful transients are injected into the critical power bus by both external and internal transients producers. Oscilloscope recordings show that the harmful transients consist of oscillatory voltages having predominant frequency components as low as 400 Hertz and high-frequency disturbances in the form of spike voltages as short as 10 μsec in duration. A study was conducted on the feasibility of developing power filters which could prevent the externally produced transients from reaching transient- sensitive electronic equipment, and prevent load-caused transients from reaching the critical power bus. Based on the findings, a single-phase filter was designed, fabricated, and experimentally evaluated.