| 摘要 |
PURPOSE:To prevent the quick change of mechanical power by making a switch to continuously supply a current to an electromagnet coil at the time of abnormal stop of a DC power source. CONSTITUTION:In an electromagnet power unit, an electromagnet coil 2 to generate a ferromagnetic field is fed by a DC power source 1. A DC variable voltage source 10 is connected through a switch 11 to constitute a power source free from power failure. This voltage source 10 consists of a self-excited converter 22 of a transformer 21, DC capacitors 23-1 and 23-2, and a bidirectional chopper circuit 24. A thyristor 11-1, a voltage detector 25, and an abnormal stop detector 26 of the DC power source 1 are provided. When the thyristor 11-1 is ignited by the output of the abnormal stop detector 26 of the DC power source 1, the current is supplied to the electromagnet coil 2 by the voltage source 10. This output voltage (the voltage of the capacitor 23-2) always has the same value as the voltage of the electromagnet coil 2, and the quick change of the current of the coil 2 is prevented. |
