| 摘要 |
<p>The circuit for measuring alternating voltages on protective switches contains a storage circuit which suppresses the voltage spikes occurring when the switch turns off. It can reproduce the actual value of the switching spike voltage without a delay and very accurately. Two capacitors (3,4) acting as the storage elements are connected alternately to the a.c. voltage being measured via one changeover switch (1) and to a voltage measurement circuit (11) via another changeover switch (2). This ensures that during each half-wave period the a.c. voltage is connected to one capacitor whilst the other capacitor voltage is being measured. The changeover switches are controlled by a null voltage switch (8) producing pulses whose durations corresp. to the voltage half-wave periods. They may consist of LMOS semiconductor switches.</p> |
