Electrostatic charge measurement in hydraulic circuits

Abstract

Electrostatic charging of hydraulic circuits is recently becoming an issue as low conducting hydraulic fluids are increasingly in use. Charge generation is more likely to accumulate and build up large voltages. These high charge accumulations are hazardous as they can damage system components such as filters, which can eventually lead to system failure. In order to develop appropriate counter measures, a precise knowledge of influencing parameters is strongly beneficial. In this paper the causes for charge generation are discussed. Furthermore, methods for charge measurement of hydraulic fluids are presented. As the researched measurement methods are considered inappropriate, a new charge measurement method is developed. The development based on the principles of Faraday-cup and Faraday-cage are discussed in detail. Moreover, the integration of the developed charge sensors into an also developed experimental setup is described. The test rig in combination with the charge sensor allows the quantitative measurement of charged fluid without influencing the fluid to be investigated. It also enables measurements under pressure, meaning that the fluid can be pressurised up to 140 bar. The experimental setup is destined to obtain a large data basis. This data basis allows the validation of a charging model for which the modelling approach is also presented in this paper. This will lay the basis for a charging model to predict the charging tendency of a hydraulic system.