| 摘要 |
The invention shows a process and a device for inspection of electrostatic filters 10 for gas purification, comprising a filter housing 12 having earthed collecting electrodes 22 and emitting electrodes 24 connected to an alternating-current-connected transformer and rectifier unit 30,38,40. The state of the filter is established during operation through capacitance measurements. The capacitance of the filter is calculated during use of that alternating-current component of the filter current and filter voltage which is of a certain frequency, preferably the fundamental tone or double the mains frequency. The voltage across the filter electrodes 22,24 is measured. A fall in voltage proportional to the filter current across a precision resistor R11 arranged in series with the electrodes, between the rectifier and earth, is measured. The direct-current part of the filter current and filter voltage and unwanted alternating- current frequencies are separated out through the use of a band-pass filter 62. The capacitance of the filter is calculated from the acquired measurement values. <IMAGE> |
