| 摘要 |
PURPOSE:To make it possible to measure a load indirectly by measuring a voltage and a current, which are supplied into the winding of a synchronous motor, obtaining effective power from the product of the voltage and the current, obtaining the product of the effective values of the voltage and the current as apparent power, obtaining power factor from both powers, and using the correlation of the power factor and the load. CONSTITUTION:A winding 31 of a synchronous motor 3 on the stator side is excited with an AC driving power supply 4. A voltage/current measuring means 11 is provided between the power supply 4 and the motor 3 and measures the voltage and the current supplied into the winding 31. A power-factor operating means 12 obtains the effective power from the product of the voltage and the current and also obtains the apparent power from the product of the effective value of the voltage and the effective value of the current. Then, the effective power is divided by the apparent power, and the power factor is obtained. In a load detecting means 13, the data of the correlation of the load and the power factor are stored in memory circuit 14 in the inside, the data of the circuit 14 are referred based on the inputted power factor with a load detecting circuit 15 and the corresponding load is obtained. |
