Abstract: The present disclosure provides a corrugated skew rolling preparation method of a magnesium alloy bar with a gradient structure, adopts a three-roller skew rolling mill, adding a corrugated curve to a flat roll rolling section of the three-roller skew rolling mill to form a corrugated roll, the billet used is as-cast magnesium alloy bar, and steps include: simulated rolling physical experiment; rolling parameters setting; bar homogenization annealing treatment; heating treatment of bars before rolling; three-roller skew mill rolling; cooling of the rolled parts after rolling. Thus improving the preparation efficiency and preparation quality of the magnesium alloy bar with gradient structure. And further improves the formiability of magnesium alloy bar with gradient structure.

Abstract: An apparatus for testing the life of a leakage current protection device having a leakage current detection circuit. In one embodiment, the apparatus a trip mechanism state generator, a fault alarm generator, a ground fault simulation unit. In operation, the ground fault simulation unit generates a simulated ground fault signal during every positive half-wave of an AC power, the simulated ground fault signal is detected by the leakage current detection circuit, the leakage current detection circuit responsively generates a signal to turn a switching device into its conductive state so as to allow a current to pass therethrough, the passed current is converted into a DC voltage in accordance with a trip mechanism state generated by the trip mechanism state generator, the fault alarm circuit receives and analyzes the DC voltage and indicates whether a fault exists in the leakage current protection device.

Abstract: An apparatus for testing the life of a leakage current protection device having a leakage current detection circuit. In one embodiment, the apparatus a trip mechanism state generator, a fault alarm generator, a ground fault simulation unit. In operation, the ground fault simulation unit generates a simulated ground fault signal during every positive half-wave of an AC power, the simulated ground fault signal is detected by the leakage current detection circuit, the leakage current detection circuit responsively generates a signal to turn a switching device into its conductive state so as to allow a current to pass therethrough, the passed current is converted into a DC voltage in accordance with a trip mechanism state generated by the trip mechanism state generator, the fault alarm circuit receives and analyzes the DC voltage and indicates whether a fault exists in the leakage current protection device.