Taking the switching power supply of information technology equipment as an example, according to the difference of electrical isolation degree between it and medical standards, this paper analyzes the additional safety measures that need to be taken when non-medical power supply is used in medical equipment, and discusses the specific implementation method of dielectric strength test according to the isolation mode of patient protection path in the equipment.
Due to different design specifications, switching power supply can be used for information technology equipment, medical equipment and other different products. Due to the characteristics of isolation requirements of medical electrical equipment, when using switching power supply that meets the requirements of different industry standards, it is necessary to conduct reasonable analysis and test verification according to its actual isolation parameters, combined with the specific application of the power supply in medical electrical equipment, and provide additional isolation measures when necessary, so as to ensure that the equipment meets the requirements of GB 9706.1-2007 [1] and GB 9706.1-2007 [1] 9706.152008 [2].
Medical power supply
According to GB 9706.1-2007 standard, the isolation parameters of medical power supply with the structure shown in Figure 1 and Figure 2 are: E1 - dielectric strength AC 1500 V, electrical gap 2.5 mm, creepage distance 4 mm; E3 - dielectric strength AC 4000 V, electrical gap 5 mm, creepage distance 8 mm; E4 - dielectric strength AC 500 v. There should be: c1-y2 capacitor, c2-x2 capacitor, C3 - equivalent to double Y1 series capacitor.
Non medical power supply.
Taking the power supply for information technology equipment as an example, according to GB 4943.1-2012 [3], the isolation parameters of non-medical power supply with the structure shown in Figure 1 and Figure 2 are: E1 dielectric strength AC 1500 V, electrical gap 2 mm; E3 dielectric strength AC 3000 V, electrical gap 4 mm; E4 dielectric strength AC 500 v. There should be: c1-y2 capacitor, c2-x2 capacitor, c3-y1 capacitor.
