| 摘要 |
<p>An electrofusion control unit for controlling the welding together of thermoplastic pipes comprises a detector 20 for connection to a supply voltage 18 to detect the end of each half cycle of the supply voltage, a frequency-to-voltage converter 22 to generate a voltage proportional to the frequency of the supply voltage, and a ramp generator 10 which generates an output ramp voltage. The detector 20 is connected to the ramp generator 10, and the voltage from the converter 22 controls the output of the ramp generator to maintain the peak amplitude of the output ramp voltage constant. The ramp voltage is subsequently compared with a difference voltage so as to regulate the RMS voltage supplied to the pipe welder.</p> |
