Ultra-Low Frequency High Voltage Generator (referred to as VLF generator) is a precision instrument specifically designed for insulation withstand voltage testing of large capacitive test objects (such as long-distance power cables, large generator stator windings, etc.). It generates 0.1Hz (or 0.05Hz, 0.02Hz) sinusoidal or cosine square wave high voltage to replace traditional power frequency (50Hz) AC withstand voltage tests and DC withstand voltage tests. It is currently the mainstream detection method recommended by the International Electrotechnical Commission (IEC) and Chinese national standards (such as DL/T 849.4, DL/T 596-2025). The following is a core analysis of this equipment: 1. Why is ultra-low frequency (0.1Hz) needed? Solving capacity problems: For long cables or large motors, their equivalent capacitance is very large. When conducting withstand voltage tests at power frequency (50Hz), the required test current is extremely large (