Transformer Oil Flow Electrification Test Method

In Transformers in which oil are forced to circle, oil takes on not only cooling medium but also insulating medium. With the raise of voltage rank and capacity of transformers, the insulating structure becoming more and more compact and insulating capability of medium is raised generally, and the oil flow is more fast, the side-effect includes picking up the charge's separation on the surface of oil and solid insulation and weakening the competence of leaking out the charges in oil, consequently, static electrification in EHV power transformers becomes one of the key factors influencing the safety and stabilization of grid.Streaming electrification became firmly the universal problem threatening the running of large transformers and the reliability and safety of the grid. It provides essential references for transformers' designing, manufacturing, operating, running and maintenance to develop the theory and experimental research on streaming electrification.Oil-paper insulation, especially, oil which is only periodically disposed and replaced is the direct cause of streaming electrification. So, it is an important premise of solving the steaming electrification to research the characteristic of static electrification .The dissertation study and sum up all kinds of equipments researching static electrification and achievements inside and outside our country, founds the testing means, which is an experimental setup used to measure the static electrification. The setup is composed of the measurement and the regulation of the flux, and the measurement and the display of the current.The flux is usually measured by the turbine sensor, the throttle sensor or the supersonic sensor etc, but those sensors aren't used to measure the ropy liquid which flows in the small-bore pipeline, so this paper introduce the new-style photoelectric sensor.There are three ways to measure the large-scale small current, such as, an amplifier plus a digital resistor, a programmable amplifier, an multi-switch plus a resistor network and a amplifier. This paper compare their advantage and disadvantage, and improve on the third way to bring forward the voltage-followed way to measure the small current.This paper designs the current-drived proportional valve to regulate the flux, which is controlled by the current by voltage -to-current commutator.Experimental results on two samples of oil from two transformers indicate: the current caused by steaming electrification depends on the velocity of oil flow.In this paper, the system of the measurement and control based on the SCM is designed, which includes the hardware and software.