Abstract: Measuring systems and methods measure particle velocity and/or particle velocity distribution and/or particle size or particle size distribution. The measuring system includes a filter for filtering collected signals which is arranged to pass signals at a relevant frequency band or at relevant frequency bands. The relevant frequency band or frequency bands are arranged to correspond to a frequency band or frequency bands defined by frequencies which exist in consequence of one or more process equipment or a process occurrence affecting to the medium flow.

Abstract: A method and a measuring system for detecting static electricity in a measuring object includes at least a sensor, a voltage meter, and a processor unit with a signal processing unit connected to the voltage meter. The sensor includes a sensing element arranged so that the electric field of the measuring object induces in the sensing element an electric signal which is proportional to the change in the electric charge of the measuring object. The sensor includes a detector including a capacitive circuit, such as a capacitor circuit, having an integrating effect on the measuring values which are read off by the voltage meter, connected between the sensing element and the voltage meter.