Manufacturers of medical electrical devices are being encouraged by TTS?to prepare for new Electromagnetic Compatibility (EMC) standards set to come into force from the start of 2019.
The revised International Medical Safety EMC Standard, IEC 60601-1-2 Edition 4, which takes effect in Europe, USA (new applications) and Canada, defines the basic and essential performance for medical equipment regarding emissions and immunity to electromagnetic disturbances.
Edition 4 responds to the increasing number of electrical devices being used directly by patients in the home healthcare environment, outside of hospitals or professional healthcare facilities. It shifts classification of the EMC requirements from relating to the usage of a medical electrical device (life supporting or non-life supporting) to the intended user and environment of a medical electrical device (home healthcare, hospital, special environment).
The home environment will often feature more mobile transmitters situated close to medical electrical devices, so immunity requirements have been revised to ensure that the devices can be operated safely in the current and future intended environments.
The revised standard requires manufacturers to take EMC into account in the risk management process and, in the risk management file, identify all risks affecting the basic safety of a medical electrical device. The practical outcome of a risk management file is a detailed EMC test plan, which the manufacturer will need to prepare prior to testing, ideally involving the EMC testing laboratory in its preparation.
The main elements in an EMC test plan are:
- Essential performances of the equipment (affecting basic safety)
- Detailed PASS / FAIL criteria for each essential performance
- The method of monitoring each essential performance while testing
- Test setups of the equipment under test (accessories, cables, operating modes etc.)
Immunity requirements have been revised to ensure that the medical electrical devices can be operated safely in the current and future intended environments. Electrical discharge immunity (IEC 61000-4-2), radiated RF field immunity (IEC 61000-4-3) and radiated magnetic field immunity (IEC 61000-4-8) requirements have been fully revised having much higher requirements now. Also, the requirements for conducted RF immunity take into account ISM and radio amateur frequencies. The radiated RF field immunity testing has been extended to cover a near field immunity testing which simulates the close proximity of external transmitters. For the devices to be installed in a vehicle a new EMC requirement of conducted transients (ISO 7632) has been introduced.
Emission requirements remain largely unchanged – for information and multimedia equipment a product standard of CISPR 32 may be used. A new test for the patient cables emissions has been introduced as an informative annex.
THE RISK MANAGEMENT PROCESS
Through the risk management process the manufacturer defines final EMC testing requirements. Manufacturers should consider the level of risk together with the test levels given in the EMC standard. The conclusion may be that different test levels, different test frequencies or different types of EMC interferences from the given requirements in the EMC standard shall be considered. It becomes the manufacturer