| 摘要 |
Plastics material pipes 10, 12 are built joined by means of an electrofusion coupling 14 having a heating coil 16 energised by the output winding 24 of an electrical generator 20 which has a field winding 22 controlled by a control circuit 26. The coupling has a pressure sensor 18 which monitors the build up of pressure which occurs in the coupling during the fusion process and, through the control circuit 26, inhibits the field winding 22 when the pressure indicates that the fusion process is complete. Alternatively, control circuit 26 may receive an input from a timer 28 to terminate the welding process. The output voltage of the generator may also be regulated by means of the circuit 26 which may have a sensing input connected at the load lid of the output power cables to compensate for voltage drop in the latter. The system eliminates the need for power semiconductors and contactors resulting in savings in weight and cost. <IMAGE> |
