| 摘要 |
<p>In a transformer having a primary winding (11) which is connectable to an a.c. voltage source (13) via switch means (14) which opens and closes at a controllable frequency, there is connected in parallel with the primary or secondary winding (11, 12) of the transformer (10) a circuit (21) which for at least a part of the time during which the switch means (14) opens maintains magnetization of the transformer (10) in a direction opposite to the direction of the magnetization caused by the subsequent closing of the switch means (14).</p> |
