The volume resistivity of the insulating oil filter
2018/5/17 Viewers:
Under the action of a constant voltage, the capacity of a medium to conduct current is called electrical conductivity, and the reciprocal of electrical conductivity is called the resistivity of the medium. That is to say, the conductivity of insulating oil is the ability to transmit current between two electrodes under certain pressure. The greater the conductivity, the stronger the ability to conduct current. The volume resistivity of insulating oil is the magnitude of the resistivity in the unit volume between the two electrodes and the insulating oil, usually expressed in P. In general, the resistance R between the poles is measured, and the electrical conductivity is calculated according to the following formula. The insulation property of the oil with small conductivity and high resistivity is good. The volume resistivity of the general new insulating oil is 1x 1012 "~1X1014Q.cm". As the temperature increases, the viscosity of the oil decreases, and the conduction velocity of some conductive particles in the oil increases, which leads to the decrease of resistivity.
The factors that affect volume resistivity of oil products have the following points.
(1) the influence of temperature. The volume resistivity of general insulating oil varies with the change of temperature, that is, the temperature rises and the volume resistivity decreases. On the contrary, it increases. Therefore, the temperature must be kept constant at the time of determination, so as not to affect the determination result.
(2) it is related to electric field intensity, just like oil test, and the volume resistivity measured by different electric field intensity is different. Therefore, in order to make the measured results comparable, the residual voltage should be determined under the prescribed electric field strength.
(3) it is related to the time of voltage application, that is, the time that the voltage is applied is different. When measuring at room temperature, the time of applying voltage is longer (such as not less than 5min). The pressure time can be reduced a little (such as 1min) at high temperature. In a word, pressure should be carried out at the specified time.
The factors that affect volume resistivity of oil products have the following points.
(1) the influence of temperature. The volume resistivity of general insulating oil varies with the change of temperature, that is, the temperature rises and the volume resistivity decreases. On the contrary, it increases. Therefore, the temperature must be kept constant at the time of determination, so as not to affect the determination result.
(2) it is related to electric field intensity, just like oil test, and the volume resistivity measured by different electric field intensity is different. Therefore, in order to make the measured results comparable, the residual voltage should be determined under the prescribed electric field strength.
(3) it is related to the time of voltage application, that is, the time that the voltage is applied is different. When measuring at room temperature, the time of applying voltage is longer (such as not less than 5min). The pressure time can be reduced a little (such as 1min) at high temperature. In a word, pressure should be carried out at the specified time.
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