What is MOPP?

MOPP is a term familiar to the designers who work on medical domain. The design aspects, approach to design, documentation are very stringent in Medical. For example, IEC60601, which calls for a safety and technical performance of a system in which IEC60601-1 is specifically for Medical domain. Most of the international markets look for IEC60601 certification for medical products to be commercialized in their country. One of the requirement for Medical standard is that there should not be any shock or any hazards to either the patients or operator. For these requirements to be met, the thoughts of safety should start at architecture level. One of the major concerns of shock is the power supply. So, power supply certified for Medical applications is the critical section in the design.  

MOPP means Means of Patient Protection and must be achieved by the power supply used in the system. The system could be a Scanner, Analyzer or some other lab equipment. These are the equipment that come into contact with patient directly. Generally, off-the-shelf power modules shall be used in these systems. The most stringent requirement as a part of certification is a two level of certification required. Two levels of MOPP is most of the power modules comply to. 

The most important requirement as a part of MOPP for a hardware person to consider is that the leakage current must be very less and there must be isolation between the input and output. To explain in depth about the power supplies used, they 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 requirement for isolation voltage, Creepage and leakage current. For a 2 levels of MOPP, 4000Vac is the isolation required. For single layer of isolation, 1000 vac isolation is required.

For example, consider the MUI30 from Polytron Devices, which is a 30W AC-DC converter module which works over a universal input of 85-264 Vac, 47-63-Hz frequency input and low leakage current under 100uA. This supply has 2xMOPP protection and as desired 4000Vac reinforced isolation. MUI30 meets all medical safety standards, including IEC/EN/ANSI/AAMI ES60601-1 and IEC/EN/UL 60950-1. Similarly, products from Artesyn, RECOM also have supplies with these standards.