Yesterday in our discussion group, a friend raised a question regarding UPS. A helpful member in the group provided an answer to this question. I have organized the question for everyone to share and learn from, and you can also share your thoughts in the comments section.Question: Can different brands of UPS be used in dual bus parallel operation?Answer 1: The two buses should be fine as they are completely independent and do not interfere with each other. I remember there was a guideline from either China Mobile or China Unicom suggesting this.Question: Each UPS output should be completely consistent, right? Does a different waveform affect the server?Answer 2: When two UPS units operate in parallel to supply the same load, their waveforms definitely need to be consistent, including voltage, frequency, and waveform. Personally, I believe using the same brand and model of UPS ensures these factors. The parallel system mainly guarantees that there is no phase difference between the outputs of the two UPS units and is designed with some logical judgments. Devices of the same brand have the same controllers, the same protocols, and good compatibility. I haven’t seen cases of parallel operation with different brands of UPS, so I cannot rule out the possibility of achieving parallel operation through various complex means.Answer 1: What I just said was not very clear; in a 2(n+1) configuration, n+1 needs to be of the same brand and model, while 2 can be of different brands.Answer 2: What you mentioned is a 2N or super 2N power supply architecture, where different brands of UPS can be used on both sides because they do not affect each other and are relatively independent. For example, in a 2N architecture, the two PDU paths in each cabinet can be powered by Schneider UPS in parallel for path A, while path B can be powered by Vertiv UPS in parallel; there is no requirement for the two PDUs to have the same phase (it does not affect the server, as both power paths will first convert AC to DC in their respective power modules).Even if both sides use the same brand of UPS, it does not guarantee that there will be no phase difference, as it mainly depends on whether the two power sources are the same. The waveform output from the inverter tracks the static bypass waveform (the static bypass waveform is the waveform of the utility power); theoretically, only in this way can the system switch instantly to static bypass during inverter failure, ensuring that the waveform aligns, and the power supply to the end devices is not affected. For the T4 2N power supply mode, having the two power sources from the same origin is inherently impossible.
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