| 摘要 |
<p>PURPOSE:To enable the removal of extraneous noise in stationary waves with the cycle almost doubling the width of an internal partial discharge pulse by employing a filter circuit, a narrow band pass filter and the like made up of a delay circuit and the like. CONSTITUTION:A partial discharge pulse of a gas insulated electric appliance is detected as distinguished from a pulse due to corona discharge in the air with a detection circuit 11 having a detection circuit 14 of an RC parallel circuit with the time constant of wavetail as specified. The detection output thereof passes through a filter circuit 12 composed of circuits 21 and 26 for delaying the pulse width of a partial discharge pulse, circuits 22 and 23 for delaying that by two or three times, addition circuits 24 and 25, a multiplication circuit 27 and the like to remove continuous extraneous noise with the cycle almost doubling the pulse width. It is further processed with an output circuit 13 having a narrow band pass filter 31 with the frequency 10% lower than the center frequency. This enables the removal of extraneous noise in stationary waves with the cycle almost doubling the width of the internal partial discharge pulse thereby ensuring a better measurement of the internal partial discharge pulse.</p> |
