| 摘要 |
PURPOSE:To achieve an economical testing under the conditions equivalent to those in the on-site installation without requiring special equipment by determining a natural circulation flow rate of an insulating oil by calculation during the operation with an oil pump provided for circulating the insulating oil through an oil piping. CONSTITUTION:A tester is arranged on the same floor as the body 1 of an oil-filled electric appliance and an oil pump 5 for circulating insulating oil and a flowmeter 6 are inserted somewhere into the course of oil pipings 3 and 4 for communicating the two units. The quantity of feed oil of the oil pump 5 is set at the value equivalent to the natural circulation flow rate of the insulating oil calculated in operation under the conditions with radiators set at a specified height and a testing for rise in the temperature is performed with the operation of the oil pump 5. The feed oil, namely, the circulation flow rate, of the oil pump 5 can be determined simply from the formula, where Q= quantity of circulated oil (m<2>/min), beta= expansion coefficient (1/ deg.C), g= loss of the oil-filled electric appliance (kcal/min), DELTAi= height (m) to the center of the radiators 2 from the center of the winding 1a, Cp= specific heat of oil (kcal/kg deg.C), Pf= friction pressure loss in the oil circulation system (kg/m<2>) and pressure loss (kg/m<2>) due to bending, branching or the like in the oil circulation system. |
