Abstract: A diagnostic device for use in the detection of a fault in an electrical apparatus, especially transformers that have electrical windings immersed in electrical insulating oil with a headspace above the oil. The device comprises a housing defining a chamber with a mouth adapted to receive a pressure relief valve on the oil tank. The device creates a fluid tight seal around the pressure relief valve and operates the pressure relief valve to extract a gas sample from the headspace into the chamber. The device may include a gas analyzer for analyzing the gas sample for the presence of acetylene, which is indicative of a fault in the apparatus.

Abstract: A portable, hand held reflectometer which employs at least one blue light emitting diode for measuring the optical brightness of an opaque material, such as a stack or pad of paper is disclosed. A brightness measuring reflectometer which employs two blue light emitting diodes arranged so as to substantially reduce measured brightness variations caused by changing the orientation of the reflectometer relative to that of the fibers contained in a fibrous material such as paper whose brightness is to be measured is also disclosed. An ultraviolet light source such as a fluorescent lamp is also employed for measuring the brightness of paper or other materials which contain ultraviolet light excitable blue wavelength emitting substances. An electronic circuit for operating the reflectometer is also disclosed which employs a negative feedback circuit for maintaining the intensity of the ultraviolet light source at a relatively constant level.