Method for determining a property of a fluid component of a fluid present in a compartment of an electrical apparatus

A method for determining a property of at least a fluid component of a fluid present in a compartment of an electrical apparatus by means of a measurement device arranged outside the compartment and comprising a chamber for receiving a quantity of the fluid from the compartment, comprising the steps of:

• a) attaching the measurement device to a port of the compartment,
• c) illuminating an optical path in the chamber with light emitted by a light source,
• d) measuring a first intensity of light received by a light detector,
• e) releasing fluid from the compartment into the chamber,
• f) measuring a second intensity of light received by the light detector,
• g) calculating a partial particle density of the fluid component from the first and the second intensity, and either
• h1) determining the property of the fluid component by using the partial particle density;
• or
• h20) measuring at least one additional parameter of the fluid in the chamber and/or of a fluid portion in the optical path, and
• h21) determining the property of the fluid component by using the partial particle density (px) and the at least one additional parameter, wherein
• the fluid present in the compartment of the electrical apparatus is a dielectric gas which comprises a background gas and an organofluorine compound selected from the group consisting of:
• fluoroethers, fluoroketones, fluoroolefins, fluoronitriles, and mixtures and/or decomposition products thereof, and
• the measurement is done non-continuously such that no material incompatibility of the dielectric gas with the measurement device arises.