剩余电压测试是电气安全领域的重要测试项目，目前实验室多采用人工模拟拔断装置进行断电操作，此实验手段无 法找到剩余电压的最大值，并且测量重复性很差。为了方便的找出剩余电压的最大值，提高剩余电压的测量重复性，提出 一种可在交流电一个周期内任一相位点处断电的装置。该装置采用模拟电路检测出交流电的零点，利用单片机进行相位时 间延时，配合机械继电器进行精确断电，在研制过程中采用多种方法实现了精确断电的要求。通过试验证明该装置的断电 精度可达±0.3 ms，测量重复性比人工装置提高了7.5倍，利用此装置配合示波器测量可方便地找出剩余电压的最大值，并 显著提高了测量稳定性。

The residual voltage testing is an important test project in electrical safety field. At present, the laboratory often used the artificial simulation to pull out the device to operate the power off. However, we could not find the maximum residual voltage value by this testing method and repeatability of measurement was poor. In order to solve these problems, a device which could be cut off at any phase point during a period of alternating current was proposed. To achieve the precise power requirements, a variety of methods were adopted, such as adopting the simulation of the circuit to detect the alternating current zero, using single chip microcomputer to phase delay time and coordinating with mechanical relay for accurate power off during the process of developing. The test results showed that the power failure accuracy of the device could reach ±0.3 ms. The repeatability of measurement was 7.5 times higher than the manual device. The maximum value of residual voltage can be easily found and the measurement stability can be improved significantly by using this device and oscilloscope measurement.