| 摘要 |
PURPOSE:To save electric power without stopping the transformer cooler even at a light load, by separating electric sources for oil pumps and for cooling fans, and by connecting the coil pumps with fixed-frequency generating means and by velocity-controlling still variably the cooling fans by means of an inverter, under a given load factor. CONSTITUTION:A command for optimizing the frequency according to a load factor L and an ambient temperature is fed from control meand 3 to an inverter 2 and also to a level discriminator 17. Where the load factor L is above L1, the command from the level discriminator 17 is fed to the switch 16 so that oil pumps 4, 5 are connected with the inverter 2 and therefore the oil pumps 4, 5 and cooling fans 6, 7 are controlled variably. When the load factor L is decreased to L1, the command from the level discriminator 17 is fed to the switch 16 so that the oil pumps 4, 5 are connected with fixed-frequency generating means 14 and a starting command is outputted to the fixed-frequency generating means 14. Therefore, the oil pumps 4, 5 are controlled at a fixed velocity corresponding to a frequency F1. |
