Know How
Zero-Crossing Switch
The test voltage is switched on in the voltage zero-crossing. Thus there are no voltage peaks at the test object because there is no abrupt uncontrolled voltage increase. This function is especially important at the high-voltage test. Voltage peaks that are higher than the test voltage may damage or even destroy the test object.
The test voltage is switched off in the current zero-crossing. Due to the impedance of the test object in combination with the high-voltage transformer there will always be a phase shift between current and voltage.