Isolation levels - query 1

[CanosSSCS]

Hello all,

I'm trying to choose the correct AC/DC power supply, and I have some questions as to Isolation levels, can anyone explained the difference between:

A) Isolation level : Primary-Secondary: 2xMOOP, Primary-Earth: 1xMOOP, Secondary-Earth: 1xMOOP (MeanWell MSP-600)
B) Isolation level : Primary-Secondary: 2xMOPP, Primary-Earth: 1xMOPP, Secondary-Earth: 1xMOPP (MeanWell MSP-1000)

I understand that MOOP stands for, means of operator protection, and MOPP stands for, means of patient protection. However, I am unclear as to what the primary and secondary refer to. I'm not fluent in electrical lingo so apologies in advance if the questions seems basic. Any/all help appreciated.

 

[RedSnake]

https://configurable.meanwell.com/newsInfo.aspx?c=5&i=639

Primary is "incoming" AC side, secondary "outgoing" DC side.

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein