DENKYUSETSUHONIOKERUIJOOKENSHUTSUSURUHOHOOYOBISOCHI

摘要

In an electron-fushion welding process a fault, e.g. due to incorrect assembly of the pipe joint components, is detected by sensing the welding current and emitting a signal to actuate an audible or visible alarm and/or to interrupt the welding process, if the welding current increases unexpectedly. A reference signal dependent upon the current dependent signal produced by the sensor and RMS to DC converter at a time t1 is held by a converter and is compared by a comparator with the current dependent signal transmitted through converter at subsequent intervals. So that the device does not react to transient current increase a delay arrangement delays the output signal for a given time.