EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Procedure; Human Factors; MEL; Aircraft
Upon receiving the aircraft in ZZZ; I noticed on the dispatch release that there were 4 MEL's attached; two of them pretty significant to the operation.  One of them was MEL 36-XX-XX that stated 'APU PNEUMATIC BLEED SYSTEM.  APU INOP.' and another one which was 34-XX-XX for 'FLIGHT MANAGEMENT SYSTEM (S) INOPERATIVE ONE INOPERATIVE'.  Having flown with the APU inop before; I was familiar with the procedures.  I accidentally assumed based on the information of the dispatch release that the APU was INOP because that is what was printed on it.  Upon arriving to the gate in ZZZ1 and after having let operations know we were coming in with the APU inop - I proceeded to shut down engine Number 2 after ground power had been connected.  A few minutes later; while realizing that the jet bridge was not moving towards us; ground ops was signaling me asking me if they could disconnect ground power - which would have made the airplane go dark with passengers for a few minutes.  The reason for this; according to them; was because that particular jet bridge was unable to move if the GPU cable was connected to the airplane.  After discussing with the chief pilot; I went ahead and shut the airplane down and we went dark for about 2-3 minutes until the jet bridge hooked up and I powered back the airplane.  About a day later; Mr. X contacted me asking me why I had not used the APU for electrics since all we had deferred was the APU bleed valve according to their records.  I explained to him that I was under the impression that the entire APU was INOP because that is what the dispatch release said.  He told me that by looking further into MEL 49-XX-XX; it clearly states that both the APU and APU BLEED cannot be deferred together; and that the information on the dispatch release should not treated as final; which is why it can be amended.  I failed to put two and two together at the gate in ZZZ1 due to the fact that we were on a quick 30 minute turn with a crew swap; and it was in my best interest to try to get us out on time since the inbound flight was already delayed.  I was also impacted by the fact that one of the FMS's was not working which was an irregular situation and it doubled the work load between the FO and I.I should have spent more time reading all the way through to 49-XX-XX which states that APU BLEED VALVE INOP and APU INOP is a no dispatch situation; and should have questioned the APU INOP line on the dispatch release which I took as final word for operational reasons; and should have gotten it amended.  In the future; when there are these many MEL's on the dispatch release; I will take my time and make sure that I go through every operational instruction; even if it means taking a delay.  I will also not allow time pressure to be a factor on situations like these; even though it was in my best interest to do so; since it clearly allowed me to miss and misinterpret the dispatch release.
EMB-175 Captain reported misunderstanding a deferred item and did not realize the APU was operational for electrical power.