DC-AC Power inverter with two MOPPs

[SebastienBoisvert]

Hello,

I'm working on a medical product that has an applied part type B, and I'm struggling to find a power inverter that has 2 MOPP.

I've been wondering if someone has experienced the same issue? I wondered if this kind of component has the same requirement as an AC-DC, two means of protection. Indeed, since the source is not 'dangerous' (the DC level will be at 24V), an isolation fault would not keep a high voltage on the DC bus.

You can see the diagram below as a reference.

The power inverter is here to provide energy from the battery to a power inlet if the product is not connected to the main supply. Before the inlet, we plan to use a toroidal transformer with 2 MOPP of protection.

Anyone can help?

 

[Benjamin Weber]

According to your diagram, the applied part is supplied directly with the 24 VDC? What kind of applied part is this? Is it fully metal? Is it conductive? If yes: Is it necessary to have this conductive connection to the patient? If yes? Maybe it should be BF?

If not, I think it should be possible to apply some kind of solid insulation between the applied part / patient connection(s) and the patient? Unfortunately you cannot apply a PE connection as one MOPP, since PE connection is not always there (when it is not connected to the supply mains)

Kind regards,
Benjamin

 

[SebastienBoisvert]

Hello Benjamin,

Thank you for your reply!

The 'applied part' would be a touch panel and probably other control and display interfaces. In my opinion, it would stay a B type.

Indeed, maybe it would be easier to applied two MOPPs at each interface instead of at the inverter.

Thus, the AC-DC and the toroidal would have 2 MOPPs, and each interface would have its own, but the inverter would be a 'generic' part.