Power supplies for medical equipment in home healthcare environment

The use of medical devices in own homes is always growing. Patients can now perform many treatments outside the hospital. Blood pressure monitors or respirators for Sleep-Disordered Breathing (SBS) are already found in private homes and houses. Electronic devices with communication connections offer new possibilities of outpatient therapy, which is more efficient and cost-effective than a lengthy hospital stay.

Medical-electrical equipment has to meet the special requirements of the home healthcare environment. The IEC60601-1-11 standard defines requirements for the safety and essential performance of medical electrical equipment and systems. In addition the devices need also be compliant to the stronger electromagnetic compatibility requirements according to the IEC 60601-1-2 4th Edition for home healthcare environment.
As home healthcare environment, the norm is understood the house or flat in which a patient is living as well as other places where patients are located, e.g. residential care home for the elderly or vehicles, but no professional health care facilities or facilities for emergency medical services.

The current version of IEC 60601-1-11 was published in April 2016 as “German version EN 60601-1-11: 2015”, a transition period of the previous standard ends 2018-12-31.
The essential performance as well as the safety of medical devices is to be maintained under almost all circumstances, so there are special requirements.

Special electrical Requirements for ME Equipment and their power supplies

The mains voltage in AC power supply networks is usually assumed to be +/- 10% of the nominal voltage, which means that the devices must operate in this range. Because of the bad electrical wiring, in many buildings, ME devices must operate in a range of 85% – 110% of the rated voltage, for life supporting or reanimating devices, are even stricter requirements, which must operate in the range of 80% – 110% of the nominal voltage.

When selecting the power supply, the manufacturer of the ME device must take care, that the power consumption matches to the output data of the power supply also in these case of use.
Furthermore, it should be noted that ME devices which are not permanently connected to the mains:

• only operated with power supplies of Protection Class II or internally powered
• are not allowed to use a functional ground
• Applied parts must be type BF or CF

The background of this requirement lies in the fact that many houses have no functioning grounding. In the case of protection class I devices, a current flows to the earth via the protective conductor in the event of a fault and triggers the residual current circuit breaker (RCD) or a fuse. This may lead to a fatal electric shock if you install a building without or with a bad grounding. Protection class II devices have a double insulation and are safe in the event of this fault.
The functional grounding is used in devices for electromagnetic interference suppression. In the case of a missing grounding, this can lead to malfunctions due to impermissible interference levels. This is also not the case for protective class II devices without a functional grounding.
It is called applied part, if there is an electrically conductive connection between patient and device. In this case, the patient connection must be isolated from the earth and the AC supply network. The current flowing through the patient to the earth when touching the patient connection may not exceed 100μA for type BF and 10μA for CF. Such an applied part can be more easily realized, if the leakage current of the power supply already meets the limit values of for BF or CF.

Special Requirements Ingress Protection

For ME devices used in home healthcare environment, an increased risk of ingress of water is assumed. For this reason, IEC 60601-1-11 specifies the IP protection class IP01, for devices which may be moved during operation or hand-held applications, the protection class IP02 according to IEC 60529 is required. Furthermore, the devices must also be protected against children (protection against the penetration of solid foreign bodies ≥ 5.6 mm) and thus not only meet IP21 or IP22.
External power supplies often meet the protection class IP40 due to the closed plastic housing, but it is a misconception that the enclosed housing automatically protects against ingress of water. Please refer to the manufacturer’s specification and test results and the position of use in the operating instruction.

Special Environment Requirements

If no other information is given in the operating instructions of the ME device, the devices must be operable under the following conditions:

Special Stability Requirements

Devices such as power supplies which are not operable and portable for movement, have to constist, in addition to impact, bump and drop test even a shock test with 15 g (IEC 60068-2-27), and a vibration test according to IEC 60068-2-64.
Shock Test
IEC 600068-2-27:2008
Peak acceleration:     15 g
Duration:                   11ms
Pulse                         Sinus Half wave
Number of shocks:    3 per direction (total 18)
Requirement:            Units fulfill Basic Safety and essential performance

Vibration Test
IEC 600068-2-64:2008
Acceleration amplitude
10Hz – 100Hz: 1,0(m/s²)²/Hz
100Hz – 200Hz -3dB / octave
200Hz – 2kHz 0,5 (m/s²)²/Hz
Duration: 30 min each vertical axis (total 3)
Requirement: Units fulfill Basic Safety and essential performance

Additional Requirements of the IEC60601-1-11

Medical devices for use in a home healthcare environment need to fulfill some requirements for the operating instructions. The instruction must be addressed to the untrained and non-specialist patient as an operator and this must also be considered in the risk analysis.

Special Requirements of the EMC according to the IEC60601-1-2

Medical devices in home healthcare environment must fulfill at least the same, in some point’s even higher, values than in professional Healthcare facility environment. This is caused in the higher pollution by unknown transmission power in different frequency bands (radio, TV, amateur radio, Smartphone Connectivity, WLAN, GSM, UMTS, LTE etc.)

The following EM phenomenon’s have higher requirements,

• Radiated RF EM fields (IEC61000-4-3) 30MHz-2,7 GHz increased immunity level of  10V/m
• For conducted RF induced by RF fields (IEC 61000-4-6) 150kHz – 80MHz is the 6V immunity level, even valid for amateur radio frequency bands, not only for ISM frequency bands.

Even with the emission the devices must cause less electromagnetic emissions, they must meet the Class B of CISPR 11, this requires a 10 dB lower than the limit value class A, which is required for use in hospitals and clinics.

FRIWO’s new power supply line „FOX“ fulfills the Requirements

FRIWO’s FOX line (FRIWO one click x-change) offers highly efficient power supplies also useable for home healthcare environments. The units meet the most stringent energy effiency standards such as DOE Level VI. Up to now it is not required for medical applications, but it offers a future-proof, which should also be taken into account when selecting the power supply especially from environmental and resource considerations. In addition to the units’ high efficiency, the minimum standby losses are crucial.

Maximum safety is guaranteed by double locking of the housings, minimum leakage currents of ≤ 10 µA and a safety insulation according 2x MOPP. This makes it possible to design a medical device with patient connection, which is considered to be an applied part of class CF
The devices were developed and tested according to the special requirements of IEC60601-1-11 Thanks to interchangeable adapters and a wide range input of 80 to 264 VAC, the units can be used worldwide. In order to meet the requirements of IEC60601-1-11, the optional adapter system with IP42 protection for FOX products must be used. In practical terms, this means that the units can be damp wiped and cleaned – an invaluable advantage in sterile environments.

Since the units are optionally available with white housings, the FOX line perfectly fits in medical applications.
The units already comply with the EMC standard IEC60601-1-2: 2014 (4th Edition) for medical devices, for use both professionally and in a home healthcare environment.
The individual units of the FOX line provide power ratings of 7.5 W (FOX6M), 12 W (FOX12M), 18 W (FOX18M) and 30 W (FOX30M) and cover voltages of 5 to 48 VDC in the standard portfolio. The product line also includes solutions with USB output, in the power rating 11 W (5 V / 2200 mA) with medical approval according to IEC 60601-1.

In addition to the devices with interchangeable adapter system, FRIWO also offers variants with fixed bottom for country-specific use and the FOX30-DM as desktop version. The standard product in the catalog covers Europe, USA / Japan, UK and Australia. Other country-specific device versions are available on request.
In addition to our direct sales and distribution partners, the units can also be ordered in small and very small quantities on the internet at www.friwo-shop.com.