PURPOSE: To secure electric capacity as required without increasing the electric capacity of an electrolytic capacitor by forming a dielectric between a power supply bar and a grand bar.

CONSTITUTION: The first insulation layer 4 is formed on one face of a power supply bar 3 and the second insulation layer 6 is formed on one face of a grand bar 5. The bar 3 and the bar 5 are overlaid with each other opposing the layer 4 to the layer 6 to form a dielectric 7 between the layers 4, 6, so that the bar 3 is formed by split conductors 3A. That is, a power supply bar is formed by overlaying the bar 3 and the bar 5 with each other via the dielectric 7 to obtain given electric capacity in the power supply bar itself. With the dielectric 7 provided between the bars 3, 5, power supply in potential-different power supply passages is stabilized. As a result, electric capacity is secured as required without increasing the electric capacity of an electrolytic capacitor.