초록 ▼

A spark-over detector for an electrostatic precipitator has a current sensor (3) which provides a signal (a) which is differentiated twice to produce a signal (c). If the level of the signal (c) is above a predetermined level then a level-detecting circuit (7) passes a signal (d) to an AND-gate (8).

A spark-over detector for an electrostatic precipitator has a current sensor (3) which provides a signal (a) which is differentiated twice to produce a signal (c). If the level of the signal (c) is above a predetermined level then a level-detecting circuit (7) passes a signal (d) to an AND-gate (8). A second level detecting circuit (9) receives the signal (a) and if this signal is above a predetermined level passes the signal (e) to a timing circuit (10) which provides a signal (f) from a first preset time after having received the signal (e) until a second preset time after the signal (e) has ceased. Thus, if a spark over starts to occur signals (d) and (f) occur simultaneously and the AND-gate produces an output signal (g) which can be used to trigger the thyristor switch circuit of the pulse generator to conduction to prevent thyristor damage or destruction.

대표청구항 ▼

A spark-over detector for detection of spark-overs in an electrostatic precipitator, said detector comprising: a pulse circuit, a current sensor, said sensor providing a current-representing voltage signal proportional with the current in said pulse circuit; a first differentiation unit receiving sa

A spark-over detector for detection of spark-overs in an electrostatic precipitator, said detector comprising: a pulse circuit, a current sensor, said sensor providing a current-representing voltage signal proportional with the current in said pulse circuit; a first differentiation unit receiving said current-representing voltage signal, to differentiate said voltage signal and to provide a first output signal; a second differentiation unit receiving said first output signal from said first differentiation unit, to differentiate said first output signal and provide a second output signal; a first level-detecting circuit providing a third output signal when said second output signal is above a preset level; and AND-gate, said AND-gate having a first and second inputs, said first input receiving said third output signal; a second level-detecting circuit providing a fourth output signal as long as said current-representing voltage is above a preset level; and a timing circuit receiving said fourth output signal and transmit a fifth signal to said second input of said AND-gate throughout a period starting at a first preset time after said fourth output signal has been received from said second level-detecting circuit and ending at a second preset time after said fourth signal has been received or after said fourth signal has ceased; the said AND-gate outputting a signal when there are simultaneous signals on its said first and second inputs, thereby to indicate that a spark-over is developing.