|Source:||National Institute of Standards and Technology|
|Date:||4/1/94 Record No.: 10063|
|Contact:||Dick Van Brunt, 301-975-2418|
Partial Discharge Analysis. Phase correlated noise near the peaks of the plus and minus parts of the 60-cycle waveform are recorded and digitized, and saved for subsequent analysis. The best commercially available instrument is expensive and complex, and lacks the important capability to store data for later reanalysis (and to maintain a history). NIST is developing new techniques to analyze signal properties using pattern recognition.
Patterns are compared against simulations to provide diagnosis of type of discharge, probable cause, and consequences (Is it changing? How soon to failure?). They are just starting a project for the NRC to test instrument cables from decommissioned plants. Also, PDA can help to interpret implications of manufacturer's specs. (picocoulomb partial discharge).
Partial Discharge in liquids has very different phenomenology from what occurs in gases, and is only partially understood. Work in this area was motivated by the need for high voltage switches for SDI, and contributes to the development of PCB replacements for transformers and capacitors.
-- Detecting trace quantities of S2F10 in small samples. S2F10, which is highly toxic, is produced in tiny quantities during partial discharge in SF6. Possible but unlikely health risk. Developing cheaper more portable instrument as add-on to a residual gas analyzer to use in place of laboratory gas chromatograph and mass spectrometer. (with ORNL and Ontario Hydro)