| 摘要 |
PURPOSE:To effect an efficient control without impairing the life of a motor of each of an oil feeding pump and a cooling fan, by controlling the frequency of an auxiliary power source by means of a device which can vary frequency, such as an inverter or the like. CONSTITUTION:An auxiliary power source 1 is connected to an inverter 2 through a changeover switch 6. When the transformer is used in a region where both the load and the frequency are high, for example, when the load is not less than 90%, the changeover switch 6 is changed over so that an oil feeding pump 3 and a cooling fan 4 are directly connected to the power source 1. On the other hand, when the load is less that 90%, the power source 1 is connected to the inverter 2 through the changeover switch 6 in order to control the number of revolutions of the motor of each of the oil feeding pump 3 and the cooling fan 4 through the change in frequency. When the transformer is used in a region where both the load and the frequency are low, since the motor current is also low, there is no problem of the effect of the inverter pulsating pulse on the motors of the oil feeding pump and the cooling fan. |
