Abstract: An electronic control system to automatically determine the validity of an apparent overheating signal from an overheat monitor of a gas-cooled dynamoelectric machine and reduce machine load or indicate a monitor malfunction. Upon receipt of an apparent overheat signal by the control system, filtration of the monitored cooling gas is automatically initiated to remove pyrolysates released into the gas by overheated elements within the machine. A normal monitor response is thereby effected, provided the overheat signal is valid. If filtration of the monitored cooling gas fails to elicit a normal response within a preselected time period a monitor malfunction is indicated. The control system initiates a scheduled reduction in machine load either subsequent to validation of overheating or as verification is initiated, and if a valid indication of overloading persists, trips the excitation and remaining load from the machine.

Abstract: In a gas-cooled dynamoelectric machine some machine parts may contain, or may be coated with, organic materials which may undergo thermal decomposition and emit pyrolysates into the machine gas coolant upon the occurrence of localized overheating in the machine parts. These pyrolysates are detectable by means of an ion chamber detector which may be put in fluid communication with the machine gas coolant. Different pyrolysates have different characteristics and thus are identifiable by various qualitative analysis techniques making it possible to locate the source of overheating in the dynamoelectric machine by knowing which parts are coated with selected organic materials. An apparatus for collecting pyrolysates is described having a multi-media collector therein for obtaining both gaseous and particulate pyrolysates.

Abstract: Certain internal parts of a gas cooled dynamoelectric machine may be coated with selected materials which will decompose at elevated temperatures to give off sub-micron particles into the machine gas coolant called pyrolysates. The presence of such pyrolysates in the machine gas coolant is indicative of localized overheating within the dynamoelectric machine. A detector is known for sensing the occurrence of these pyrolysates and hence a monitoring system has been devised for giving an early warning of machine overheating. Occasionally, oil mist particles from the machine may become entrained in the machine gas coolant and cause a false overheating signal from the detector. A second detector has been devised which may be used in combination with the first detector to provide a redundant monitoring system which will provide immediate validation of the presence of pyrolysate particles and which monitoring system is testable on line.

Abstract: An improved detector apparatus is provided in combination with a gas cooled dynamoelectric machine for detecting the presence of pyrolysate products in the machine gas coolant indictive of localized overheating of certain dynamoelectric machine parts. The detector apparatus is of the type which analyzes an ionized gas sample by measuring the current flow in the gas sample. A decrease in current flow is indicative of the presence of submicron particulates. The present invention resides in heating the gaseous sample to eliminate more volatile submicron particulates so that the output signal from the detector apparatus is indicative only of the presence of pyrolysate products resulting from the localized overheating of certain dynamoelectric machine parts.