| 摘要 |
PURPOSE:To prevent electrolytic corrosion of an earth electrode, in a new urban transit system concurrently provided to a DC electric railway, by connecting a neutral point of a feeding transformer to the earth through a capacitor and parallelly connecting a parallel circuit of discharge high resistance and discharge unit. CONSTITUTION:Feeding currents I1, I2 of an electric car D in a DC railway section are returned partially as DC stray currents I''1, I''2 via an earth electrode E of a new urban transit system feeding circuit flowing through in a low voltage secondary winding L and low voltage feeding wire K to a DC substation SS via the earth electrode E. Then a neutral point of the secondary winding L and the earth electrode E are connected through a capacitor C to cut off a DC stray current and prevent electrolytic corrosion, and an electric charge always to the capacitor C can be discharged by a high resistor r paralelly provided. Further a parallelly provided discharge unit SG is automatically discharged and short circuited to perform protection by a rise of terminal voltage of the capacitor C at one-line earth fault, from a direct earth circuit for a short time and automatically perform cut off by a feeding circuit protector at the new urban transit system side. |
