I'm looking for clarification for the NCS DC PMs. I understand the matrix for redundancy configuration i.e 1+1, 2+0, etc. and it clearly states that any combination of PMs can be used. But I'm confused about the matrix for power module settings as shown below. The chassis has 4 PMs and the inputs are: 1A & 2A for PM 1, 3A & 4A for PM 2, 1B & 2B for PM 4, and 3B & 4B for PM 3. There are no designated A/B feeds for each PM. Am I correct to assume this means that for PM 1, Feed A is input 1A and Feed B for it is 2A? What I'm trying to determine is the Work vs Protect capability with only 1 input per PSU. We have only 2A and 2B feeds available for a chassis. By the redundancy matrix, that means we can supply 2As to 1 PM and 2Bs to a second PM (preferably on the B side) and configure them as either 2+0 or 1+1 correct? Or, we should be able to supply the 2As to both A-side PMs and the 2Bs to both B-side PMs and configure them as 2+2 correct? Then if we ever wanted 3+1 we would just need 1 more input to any 2 of the PMs to create W, W, WP, WP for a total of 6 inputs. Correct? The feed A and Feed B for a module is just confusing me and I want to confirm that each PSU only needs 1 input to fully power. If I'm correct here, then to make PM 3 Power, it has to have input 3B and to make it Protect it has to have 4B or both if it's to be Power-Protect?
Maybe I was over thinking that. After looking at individual PM specs, it appears the second feed to each PM is just for input redundancy and has nothing to do with the W, P, W/P setting. (I said it incorrectly prior as Power/Protect) If so then I see that the matrix just means for Work, A-side is mandatory for 1 module to be in either slot and B-side is optional for a 3rd module in either PM 3 or PM 4 slot. For Protect, an A-side module is optional as long as the other is Work but B-side modules are mandatory when both A-sides are Work. For Work and Protect, A-side has to have both slots a combo of work and protect and Work and Protect has to be in either B-side slot or both. But then the darn thing says whats shown below that any combination of PMs can from all 4 PMs so that just confuses it again. What the heck?
