Over time, safety and environmental standards have been changed for the benefit of all in the medical industry. Here at Components Bureau we can help you decide on the most efficient power choice for your application.
Medical power supplies are used in multiple medical equipment applications including MRI, X-ray, CT and PET scanners, DNA equipment, ultrasound, diagnostic equipment and automated pharmaceutical dispensers.
There is a trend for all medical equipment to make them compact, light-weight and efficient.
All medical equipment has to meet a set of safety standards that keep the patient and the operator safe.
The same is the case with the medical power supplies, where they have to meet a specific set of standards. Tomorrows power supplies are moving to digital controlled power, allowing much more control over voltage and current, we already have a wide choice here available from many leading brands.
Let us look at the Standard for the Medical Power supplies.
Standards to maintain Medical Power Supplies
1. MOPP (Means of Patient Protection) & MOOP (Operator protection)
A medical power supply should protect both the patient (referred to as MOPP) and operator (referred to as MOOP) of the medical equipment.
A small electric current may not affect a healthy person, but hospital patients are in a weak condition. Therefore, any exposure to the smallest current leakages can put their life at risk.
Also, the power supply should be safe for the operator as well. Any leaked current may potentially harm the operator who may also have direct physical contact with the patient's body, consequently the current may affect the patient. A limit is prescribed for the allowed leakage current for the medical equipment (irrespective of the limit of the power supply).
Therefore, all medical power supplies and equipment should come with the lowest leakage levels prescribed.
2. Upgrade to the latest power supply standards
In medical equipment, there are different safety requirements for medical power supplies. These safety requirements are referred to as the IEC 60601-1 standard.
Medical power supplies have to follow the IEC 60601-1 standard (3rd edition, originated in 2005). Now, there have been different editions to the IEC 60601-1 standard.
Over time, these editions have added many precautions and measures for ensuring safety while using medical power supplies.
One major advancement in the 3rd edition is the introduction of the “Risk Management Process” that will include an audit of the manufacturer’s compliance with ISO14971 (Risk Management Process).
All the manufacturers have to provide effective and reliable isolation for the internal voltage stages, DC output, the AC input (to the power supply) to avoid all chances of an electric shock. There has to be effective isolation between the conductor and the electronic components. The IEC 60601-1 has set a minimum distance for the space between all elements, it also prescribes reliable insulation and that’s why medical power supplies come with reinforced insulation.
Reinforced insulation is tested using dielectric strength testing, where all medical power supplies are tested for higher voltages to ensure that there is no failure.
The power supplies that are verified to operate in less than 4K Vac are used for medical application, where the reinforced insulation is done to avoid contact between the AC input and the patient.
Maximum allowed earth leakage is 300μA worldwide, but keep in mind that this is a combined limit for both the power supply and the medical equipment together.
Therefore, manufacturers follow the process to make the lowest leakage current power supplies by adding additional layers of insulation to their product.
After tackling all these major safety checkmarks, the EMC (Electromagnetic Compliance) performance is the next critical issue for all medical power supply manufacturers. All modern power supplies are of switch-mode type, as these are more compact and efficient than linear power supplies.
However, switch mode supplies are known for generating EMI (electromagnetic interference) and then the EMI filters are used to limit the unwanted electrical noise. Where the capacitors present in the EMI filters allow the smallest amount of leaked current to follow, which reduces the amount of interference.
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