Timeline for Why does the Cray 2 use 400 Hz power, and why generate that from motors?
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 31 at 3:09 | comment | added | Simon Kissane | Not just Cray's. Per en.wikipedia.org/wiki/IBM_308X the IBM 3081 mainframe (announced Nov 1980) needed 400Hz power. IBM would sell you the optional IBM 3089 motor/generator unit to convert 60Hz/50Hz to 400Hz, or you could do it yourself using a third party solution. I expect large data centres that may have already had lots of 400Hz systems (including non-IBM systems) would likely have gone for the third-party option. Maybe even IBM themselves in their own data centres which could contain easily contain dozens of high end mainframes (for testing, development, or remote customer use) | |
| Sep 1, 2018 at 23:48 | comment | added | Simon Brady | As a reference for military standardisation, see the various iterations of MIL-STD-704, "Aircraft Electric Power Characteristics." | |
| Aug 30, 2018 at 21:16 | comment | added | tofro | Mil Standards do, however specify 108V instead of 208 the Cray wants.@kingledion | |
| Aug 30, 2018 at 20:41 | comment | added | kingledion | @tofro Indeed, I can confirm that Navy radar and associated control systems runs 400 Hz. There is a whole separate electrical system installed to provide this power to the combat systems suite. | |
| Aug 30, 2018 at 15:36 | answer | added | Spehro 'speff' Pefhany | timeline score: 8 | |
| Aug 30, 2018 at 11:20 | answer | added | tofro | timeline score: 4 | |
| Aug 30, 2018 at 9:43 | vote | accept | Omar and Lorraine | ||
| Aug 29, 2018 at 23:30 | answer | added | lvd | timeline score: 5 | |
| Aug 29, 2018 at 21:20 | answer | added | grahamj42 | timeline score: 9 | |
| Aug 29, 2018 at 17:37 | answer | added | Raffzahn | timeline score: 26 | |
| Aug 29, 2018 at 17:22 | comment | added | Jules | It's perhaps worth noting at this point that Seymour Cray had a military background, and that many of his customers were military or other government groups. If this was the kind of power supply they'd expect, he'd know that and would provide it for them. | |
| Aug 29, 2018 at 15:26 | answer | added | Maury Markowitz | timeline score: 48 | |
| Aug 29, 2018 at 13:49 | comment | added | tofro | 400Hz is indeed a standard in Aircraft, and especially, military installations. I can only guess, but would assume the generators have been used to completely isolate and protect the non-neglectable investment in a Cray from mains disturbances like over-current, frequency drift, and especially lightning strike. The mechanical coupling can achieve that, any electrical means cannot. | |
| Aug 29, 2018 at 13:42 | comment | added | Stephen Kitt | I don’t know why, but 400 Hz was used for large mainframe systems before the Cray 2. It’s used in the aircraft industry and on ships because it allows the use of smaller and lighter transformers (lighter because they don’t need as much iron as 50/60 Hz transformers). So perhaps this is used to allow smaller motors to be used in the cooling pumps? | |
| Aug 29, 2018 at 13:34 | history | asked | Omar and Lorraine | CC BY-SA 4.0 |