内部电源设备与网电源设备的检测差异

结论：分类影响的不只是几个项目，而是整套测试的组织方式

医用电气设备按供电方式可以分为由内部电源供电的设备和由网电源供电的设备。这个分类影响一系列项目 ——哪些漏电流需要测、耐压试验怎么做、单一故障状态包括哪些、防电击的措施要求是什么。

实务中的复杂之处在于：很多设备是可切换的。 电动轮椅平时用电池，充电时接网电源；某些设备可以用电池也可以用适配器直接供电。这类设备的测试组织需要覆盖各种状态。

两类设备的差异

注意「内部电源设备风险较小」不等于「不需要考察」。 内部电源设备有自己的风险集中点——电池、大电流回路、以及充电时进入的网电源部分。

可切换设备的处理

这是实务中的重点。可切换设备需要在各个状态下考察：

仅电池供电状态。 按内部电源设备考察。

连接网电源状态。 按网电源设备考察。

充电中同时使用的状态。 如果产品允许边充边用，这个状态要单独考察。它是两类风险同时存在的状态。

状态切换过程。 插拔电源时的行为，是否有异常。

「边充边用」这个状态最需要注意。 很多电动轮椅在说明书中禁止边充边用，但实际中使用者可能这样做。如果产品从结构上不能防止，就应当按这个状态考察安全性。

各自的考察重点

内部电源设备的重点：

电池相关的全套考察（前面专门讲过）；大电流回路的发热与保护；电压虽低但电流大时的能量风险；电池耗尽时的行为（是否安全停止）；以及电磁兼容（电池供电设备的抗扰度考察有其特点）。

网电源设备的重点：

网电源部分的绝缘配置；漏电流的完整测量；保护接地的连续性与阻抗（适用时）；电源中断与恢复的行为；过压与欠压条件下的表现；以及电源线、插头、内部布线的要求。

可切换设备两者都要做，工作量大于单一类型的设备，这一点在项目规划时要考虑到。

分类判断上的注意点

看设备在什么状态下执行功能。 如果设备只在接网电源时工作，即使内置电池（仅作后备），分类判断也不同。

充电器是否为设备的一部分。 内置充电器与外置充电器的处理不同。外置充电器可能需要单独考察。

适配器的角色。 用适配器供电的设备，适配器是否属于设备的一部分、是否随设备提供、是否指定型号。

多种供电方式。 有些设备支持多种方式，各方式都要考察。

「外置适配器」是实务中容易含糊的地方。 如果适配器是通用件由使用者自备，那么设备的安全就依赖于一个不受控的部件。建议明确指定适配器型号并随机提供，把这个不确定性消除。

电源相关的单一故障

两类设备的单一故障项不同：

内部电源设备： 电池短路、电池反接、充电控制失效、保护电路失效、大电流回路元件失效。

网电源设备： 保护接地断开、中性线断开、相线断开、变压器故障、电源部分元件失效。

可切换设备： 两组都要做，另外还有切换相关的故障——比如充电中断开电源、充电中电池故障。

故障项的清单建议在送检前与实验室确认，避免遗漏或者重复。

资料准备上的差异

内部电源设备要准备： 电池规格书、电池管理电路资料、充电器规格、电池运输相关文件。

网电源设备要准备： 电源部分电路图、变压器规格、绝缘配置说明、电源线与插头的规格。

两类都要准备： 整机电路图、元件清单、结构图、使用说明书、风险文件。

「绝缘配置说明」对网电源设备很关键，它是确定耐压试验点和电压的依据。这份资料准备得清楚，测试的效率会明显提高。

电磁兼容方面的差异

两类设备在电磁兼容测试上也有差异：

内部电源设备。 不涉及电源端口的传导发射和传导抗扰度（无网电源连接时）。但在充电状态下，这些项目适用。

网电源设备。 完整的端口测试，含电源端口。

可切换设备。 要在各状态下测试，或者按较严的状态测。

充电状态的测试容易被漏掉。 产品平时电池供电，充电时连接网电源，此时电源端口的相关项目是适用的。测试方案应当明确包含充电状态。

说明书中的相关内容

供电方式相关的信息应当在说明书中写清楚：

供电方式与额定参数；配套充电器或适配器的型号；充电方法与限制；能否边充边用；电池耗尽时的表现与处理；停电时的行为（适用时）；以及电源线的更换要求（适用时）。

「能否边充边用」应当明确写出，并且如果禁止，建议在结构上也做相应的防止措施。仅靠文字禁止而结构上允许的用法，实际中一定会发生。

我们的做法

承接委托时，我们会先确认设备的供电方式和各种使用状态，特别是可切换设备的各个状态。 状态清单确定之后，测试项目的组织才有依据。

对于允许或可能出现「边充边用」的产品，我们会把这个状态作为独立的测试状态。说明书禁止但结构上不能防止的用法，仍然是可预见的使用方式。

如果你有带电池且可充电的产品需要安排测试，想先理清测试状态和项目，可以把产品资料和供电方式说明发过来一起讨论，或者直接联系：132 4819 8029。能力范围见服务介绍，送检要求见送检要求，其他问题见常见问题。

English version

Conclusion. Medical electrical equipment is classified by supply as internally powered or mains powered. The classification affects a whole series of items: which leakage measurements apply, how dielectric strength testing is performed, which single fault conditions are included, and what protective measures against electric shock are required. The practical complication is that many products switch between the two. A powered wheelchair runs on battery and connects to mains when charging; some equipment can run on battery or directly from an adaptor. Testing such equipment must cover every state.

Differences between the two. For internally powered equipment the shock risk source is limited where internal voltages are low, while mains powered equipment faces direct risk from mains voltage. Some leakage items do not apply to internally powered equipment, while mains powered equipment needs the full set. Dielectric testing follows the actual insulation arrangement in the first case and involves mains-side insulation in the second. Protective earth is usually absent in the first and depends on class in the second. Single fault conditions centre on the battery in the first and include mains-related faults in the second. And supply interruption means battery exhaustion in the first and power failure in the second. Note that lower risk for internally powered equipment does not mean no assessment: such equipment has its own concentrations of risk in the battery, in high-current circuits, and in the mains-side section entered during charging.

Handling switchable equipment. This is the practical focus, and such equipment must be assessed in each state. On battery alone, assess as internally powered. Connected to mains, assess as mains powered. Charging while in use, if the product permits it, must be assessed separately, being the state in which both categories of risk are present simultaneously. And the transition itself must be assessed, checking behaviour when the supply is connected and disconnected. Charging while in use deserves the most attention: many powered wheelchairs prohibit it in the instructions, yet users may do it anyway. Where the product cannot prevent it structurally, safety should be assessed in that state.

Focus for each. For internally powered equipment: the full set of battery-related assessments discussed separately; heating and protection in high-current circuits; energy hazards where voltage is low but current is high; behaviour on battery exhaustion, meaning whether it stops safely; and electromagnetic compatibility, immunity assessment of battery-powered equipment having its own characteristics. For mains powered equipment: the mains-side insulation arrangement; the complete set of leakage measurements; protective earth continuity and impedance where applicable; behaviour on supply interruption and restoration; performance under over- and undervoltage; and requirements on supply cords, plugs and internal wiring. Switchable equipment needs both, which is more work than a single-type device and should be allowed for when planning.

Points in classification. Consider the state in which the equipment performs its function: where it works only when connected to mains, an internal battery serving only as backup leads to a different classification. Consider whether the charger forms part of the equipment, since internal and external chargers are handled differently and an external charger may need separate assessment. Consider the adaptor's role, meaning whether it forms part of the equipment, is supplied with it, and is a specified model. And consider multiple supply arrangements, each of which must be assessed. External adaptors are where practice most often becomes vague: where the adaptor is a generic item supplied by the user, equipment safety depends on an uncontrolled component. Specify the adaptor model and supply it with the product, removing that uncertainty.

Supply-related single faults. For internally powered equipment: battery short circuit, battery reverse connection, charge control failure, protection circuit failure and failure of high-current circuit components. For mains powered equipment: interruption of protective earth, neutral or line conductor, transformer faults and failure of supply-section components. For switchable equipment: both sets, plus transition-related faults such as disconnection during charging and battery faults during charging. Agree the fault list with the laboratory before submission, to avoid both omission and duplication.

Differences in documentation. Internally powered equipment needs the cell specification, battery management circuit documentation, charger specification and battery transport documentation. Mains powered equipment needs supply-section circuit diagrams, transformer specifications, an insulation arrangement description and supply cord and plug specifications. Both need overall circuit diagrams, component lists, construction drawings, instructions for use and risk documentation. The insulation arrangement description is critical for mains powered equipment, being the basis for determining dielectric test points and voltages; prepared clearly, it improves testing efficiency noticeably.

How we handle it. We confirm the supply arrangement and every operating state at the outset, switchable equipment especially. Only with the state list settled can test items be organised. For products that permit or cannot prevent charging while in use, we treat that as a separate test state: a use prohibited by the instructions but not prevented by the construction remains foreseeable.

Send us the product documentation and supply arrangement and we will map the states and items. Phone or WeChat: +86 132 4819 8029.