The HZ-109S Primary Current Injection Tester adopts ARM chip technology for controlling output and a high-capacity toroidal transformer, and is equipped with an LCD display meter. It can simultaneously display primary current, secondary current, turn ratio, and the actuation time of the stopwatch connection (electric potential). The product features a sleek design, large output capacity, compact size, and lightweight construction, with an external aluminum alloy case and PC panel. It is primarily suited for CT turn ratio and contact resistance testing in power systems, as well as other applications requiring high current testing.