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Choosing the Right Power Supply for Medical Applications

the power

Medical Power Supplies Buyers Guide

By Mark Casilang
Jameco Product Marketing Engineer

Basic terms of how to choose the right power supply.

Medical power supplies are designed to some of the most exacting standards. Each device must operate in accordance with specific standards to protect patients and operators from electrocution.

Applied Parts Classification

Medical power supplies are categorized into one of three applied parts types – body type (B), body floating type (BF) and cardiac floating type (CF). These applied parts determine the amount required of other attributes such as isolation voltage, creepage and leakage current.

Floating refers to an ungrounded power supply that is not referenced to another output. Floating outputs are fully isolated.
Power Supply
Mean Well Medical Grade Power Supply


Type B refers to devices that operate within the patient vicinity, which is described as six feet around a patient's chair or bed. They do not touch the patient electronically and are grounded. These devices include operating room lights, hospital beds, automated medication dispensers and x-ray machines.

Type BF devices deliver electrical energy signals to or from the patient. These include electrosurgical devices, endoscopes and electrical thermometers.

Type
Types of Medical Grade Power Supplies


Type CF devices are similar to BF, except they supply power to devices connected to the heart, such as a defibrillator, external pacemaker or intracardiac ECG electrodes. Type CF requires a higher degree of protection against electrical shock than BF types.

Applied Parts Requirements:

Classification
Isolation Requirement
Creepage Requirement
Insulation Requirement
Type B
1500 Vac
2.5 mm
Double
Type BF
3000 Vac
5 mm
Basic
Type CF
4000 Vac
8 mm
Double


Regardless of classification, medical devices may not exceed 500uA leakage current, or 300uA for UL approval. Double insulation is a two-level system with basic plus supplementary insulation, where supplementary insulation provides a second level of protection by adding a layer of insulating material with a minimum of 0.4mm thickness. Protective earth (PE) is an equipment grounding conductor that keeps the exposed conductive surfaces of a device to earth by not having current flow into it.

Creepage is the distance between the point of origin and the point of termination along the surface of the insulation.

Means of Protection Classification

All medical power supplies must include at least one Means of Protection (MOP) in order to prevent patients and operators from electrocution. A MOP includes safety insulation, protective earth, creepage, and protective insulation. There are different requirements for Means of Patient Protection (MOPP) and Means of Operator Protection (MOOP).

MOP Requirements:

Classification
Isolation Requirement
Creepage Requirement
Insulation Requirement
One MOOP
1500 Vac
2.5 mm
Basic
Two MOOP
3000 Vac
5 mm
Double
One MOPP
1500 Vac
8 mm
Basic
Two MOPP
4000 Vac
8 mm
Double


The Mean Well GSMB series medical power supplies are applied parts type BF and classified as two MOPP (2 x MOPP). To achieve 2 x MOPP qualification, the device must pass an isolation test requiring 4,000 VAC and a creepage distance of 8mm. This is over twice the VAC requirement and twice the creepage requirement needed to achieve one MOPP.

Selecting a 2 x MOPP power supply can be the most favorable in that it can allow for a common power supply to be used for more than one product as well as providing the highest level of protection.

Jameco carries a variety of medical power supplies from Mean Well including enclosed, open frame, table top and wall mount power supplies. Check out our Mean Well Store for even more Mean Well products.

Enclosed Medical Power Supplies

Open Frame Medical Power Supplies

Table Top Medical Power Supplies

Wall Mount Medical Power Supplies

For more information on selecting specific power supplies visit the Power Resource Center.


These are some of the things to consider when selecting a medical power supply. What are some other things you look for when selecting a power supply? Let us know at [email protected].