... .1HZ Digital Very-low-Frequency High Voltage Tester 1,Small volume, light weight, easily ... TesterThe new generation of AC withstand tester, replacing harmonic withstand tester, is widely used in AC withstand ... power Frequency.2. AC ultra-low frequency tester doesn’t form tree-clearance in the insulating ... displayed; testing reports can be printed.3. Auto-protection of over-current and over-voltage, the ...