Medical and ITE Power Supply Safety Standard - IEC60601 & IEC60950

Medical Power Supply & ITE Power Supply Expected To Be Big In The Market

ITE Power Supply & Medical Power Supply

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Medical Power Supply & ITE Power Supply

Demand in the open frame power supplies and switching power supply adapters market, which includes medical power supplies and information technology equipment (ITE) applications, would increase from $14.8 billion in 2009 to $20.6 billion in 2014, at a compounded annual growth rate (CAGR) of 6.8 percent. A report just issued by Frost & Sullivan projects that the world power-supply market for medical applications will grow from revenues of $350 million in 2005 to $438.1 million in 2012. These numbers represent just a fraction of the overall power-supply market in which the top vendors can exceed $1 billion in annual revenue. Nevertheless, medical applications represent an attractive niche for some vendors because of switching power-supply products, once qualified for use in the applications, can have very long life cycles. With the burgeoning market for medical power supply and ITE apparatuses, power supply designers have become more familiar with the particular compliance standards required. New standards are being proposed that would change the medical-device and ITE approval process, literally turning the current method upside down.

Switching power supply is driven by the demand for electrical and electronic equipment used in various applications such as IT, Telecom, Industrial and Consumer Electronics. The demand for switching power connectors in the IT applications (ITE) is driven by applications such as computers, Liquid Crystal Display (LCD) and plasma displays, office equipment, servers, and networking equipment, the industrial market is driven by applications such as motor control, automated test and measurement instrument, and so on.

Using digital technology to control a switching power supply adds complexity and this if often measured in terms of cost. But the return on that cost is flexibility, far beyond that offered by an analogue solution. Power supply manufacturers continue to put their support behind open standards such as the PMBus protocol. By using a common protocol, switching power supplies from different vendors can be mixed and matched, giving the engineer more design freedom without sacrificing the benefits of digital technology.

There are critical demands for safety and reliability and lengthy cycles for medical power supply qualification. Medical switch-mode power supplies are used in a wide range of devices that include IV pumps, MRI, X-ray, CT and PET scanners, blood analyzers, patient monitors, and robotic surgical devices. Because any isolation shortcoming would result in a higher risk of electric shock, effective and reliable isolation between a power supply's input and its output is the first and most basic requirement. Several factors contribute to effective isolation, including spacing between conductive parts. Although IEC 60601 standards lay down minimum spacing distances, it is important to note that these are greater than spacing distances prescribed by relevant standards for industrial and general-purpose power supplies.

Power Supply Quality Certifications

Medical equipment is highly regulated and held to a higher level of safety than nearly all other types of equipment on the market since the performance of power supplies in such applications can be potentially life-saving. Medical equipment may be used on patients who are not able to respond to hazardous conditions or pain, an actual electrical connection between the equipment and patient may exist, and certain types of medical equipment function as life support, the failure of which could result in the death of the patient. The international safety standard for medical equipment is IEC60601-1 and there are three regional variants: EN60601-1 in Europe, UL60601-1 in the US, and CSA22.2 No 60601.1 in Canada. In all cases, the legislation covers protection against electric shock, protection against fire and mechanical hazards. IEC is the International Electrotechnical Committee. UL, CSA TUV and EN standards are derived from the IEC standards. It's important to consider how these standards affect the design and specification of power supplies used in medical applications.

IE 60601 national standards by country

Country / Region	Standard Adapted From IEC60601-1
United States	UL 60601-1 (U.S. national deviations) (Note: UL60601/1 was previously numbered UL 2601-1)
Canada	CAN/CSA C22.2 No.606.1 (Canadian national deviations)
European Union	EN 60601-1 (Identical to IEC 60601-1) (Known as BS EN 60601-1 in the United Kingdom)

The international medical standard IEC 60601-1 requires that maximum patient touch current (the current flowing between the patient and ground) from all such devices does not exceed 100 µA (microamps). Underwriters Laboratories has established standard UL 60601-1, which has similar requirements and serves as a industry standard in the U.S. and Canada. Generally speaking, hospitals in the U.S. and Canada will not allow medical electrical equipment to be used unless they meet UL standards. A maximum patient touch current of 100 µA is difficult to achieve using normal power strips and one conventional solution is to have a large isolation transformer in a box sitting on the floor near the wall outlet.

The leakage current requirements laid down by UL 60601 are difficult to meet. The maximum permissible earth leakage is 300µA for worldwide approvals, but this figure applies to the end-product as a whole, not just the power supply. To allow for additional leakage in other components it's a good idea to have an even lower leakage current from the power supply

Reinforced or double insulation in supplies which, for example, operate from a 240Vac main, must withstand a dielectric test at 4kVac for medical applications, whereas the corresponding figure for industrial use is just 3kVac. This difference must be taken into account when choosing a power supply. Those approved to less than 4kVac may be used in medical applications as part of a reinforced barrier, assuming the insulation provided by the power connector is regarded as a lesser "basic" or "supplementary" barrier.

Medical equipment will often have lives dependent upon its reliable operation. Power supplies must not only deliver the specified electrical performance but must also meet stringent specifications with respect to isolation in order that patients and medical staff are protected from the risk of electric shock.

ITE Power Supply Safety Certifications

Whether your ITE product is an open frame power connector for use in different application areas or an external power supply, a switching mode power supply or a linear one, all ITE suppliers need to obtain various certifications for accessing the market: