医用泄漏电流测量网络的校准技术研究

研究了GB 9706.1-2007医用泄漏电流测量网络的校准技术。分析了在DC~1MHz频率范围内校准测量网络的输入阻抗和传输特性的必要性,指出测量网络具有准确的频响特性是实现泄漏电流测量的先决条件;提出了测量网络的校准方法,并分析了测量网络的频响参数标准值。通过分析测试线分布电感对传输特性校准的影响,指出电压表高频共模抑制能力的不足将带来显著的误差。基于DDS、I-V转换和隔离测量等技术,研制了一款多功能的泄漏电流校准仪,能够实现测量网络的输入阻抗和传输电压比的自动扫频校准,满足医用泄漏电流测试仪的校准需要。

Research on the Calibration of Measuring Network in Medical Leakage Current Testers

The calibration of measuring network in medical leakage current testers is researched, in compliance with the standard of GB 9706. 1-2007. It is necessary to calibrate the input-impedance and transfer-characteristic in the frequency range from DC to 1MHz. It is pointed out that correct frequency response characters are the precondition of leakage current measurement, and the calibration method of network is pro-posed, whose standard values of input-impedance and transfer-ratio are calculated then. The influence of distributed inductance on the calibration of transfer-characteristic is analyzed, and the high frequency common-mode-rejection ability of voltage meter in network’ s respond port is the main error source. Based on the technologies of DDS, I-V conversion and isolation-measurement, a multifunctional leakage current calibrator is developed, which can take automatic sweep in frequency to calibrations of input-impedance and transfer-ratio. The Calibrator meets the require-ments of medical leakage current testers well.