Improvements in RF monitoring system on generators

An improved RF monitoring system for generators is described. A capacitive coupling is shown to be much more sensitive than the currently used magnetic coupling through a current transformer. The increase in sensitivity results in an improved coupling between the generator´s neutral grounding lead and the monitor. An RC high-pass filter is shown to be an effective coupler, because it does not attenuate the RF noise or create saturation problems as in the case of magnetic coupling. By selecting an RC filter with higher capacitance than the stray capacitances created by the typical generator grounding transformer, the coupler can detect arcing signals in any generator, regardless of the type of neutral grounding transformer used. Even though there is an ohmic contact to the neutral lead, the protections to the added RF instrumentation assure that the protective relaying scheme is not degraded.<>