Does anyone know where to find the creepage distances for 115V/400Hz power supply circuit boards in civilian aircraft?
Similar to what IEC/UL60601 says for medical. I have the numbers for mil but not sure whether civilian is the same. DO-160E is (to my surprise) silent about this topic.
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Regards, Joerg
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That sounds too high. Mil allows down to 1.5mm for low power stuff in some situations (under 150V). Lower power usually meaning that it does not exceed 50W. Medical is 4/8mm.
Do you remember what the standard was called?
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Regards, Joerg
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115V/400Hz | > | power supply circuit boards in civilian aircraft? | > | | > | Similar to what IEC/UL60601 says for medical. I have the numbers for | > mil | > | but not sure whether civilian is the same. DO-160E is (to my surprise) | > | silent about this topic. | > | | > | -- | > | Regards, Joerg | > | | > |
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| > | | > | "gmail" domain blocked because of excessive spam. | > | Use another domain or send PM. | >
| > Double or single insulation? If I recall, its 4mm single 8mm double. And | > a whole other story above 150v. | >
| | That sounds too high. Mil allows down to 1.5mm for low power stuff in | some situations (under 150V). Lower power usually meaning that it does | not exceed 50W. Medical is 4/8mm. | | Do you remember what the standard was called? |
Well, whichever one it is, I'd say if you follow what the medical one says, it should be stringent enough to cover airplanes. (unless there's a military one). The only other concerned parties should be the people in the airplane and the insurance company. ;-)
Your creepage and clearance distance depends (as you know) on Peak Working voltage, Transient voltages, Insulation surface and alltitude. Maybe IEC 60664-1 can help you (table A.2).
One example, up to 33000ft, for clearance, you need to multiply with
3.02. I assume the civilian values are derived from this std.
After 12 hours my posting did not appear over here. I already sent you a reply directly.
Creepage and Clearance distances depend on working voltage, maximum transient voltage, surface characteristics of creepage paths and air pressure.
IEC 60664-1 deals with these issues, many product standard derive there creepage/clearance requirements from this std. Table A.2 gives the multipliers for higher altitudes. For example for 33000 ft (10 km), the multiplier for clearance through air is 3.02.
You could do worse than to consult IEC60664, or even the ancient VDE0804. These all have pressure/altitude information.
Aircraft standards tend to be controlled by conformance documents relevent to the model, issued by their manufacturer. This is a pretty specialized field of power conversion , possibly approached most sensibly for the first time from the ground support or test/diagnostics end.
In military standards, more emphasis is actually placed on creepage and clearance at the connector set, where it is assumed that the most fragile and concentrated safety interface will occur, not in the built-in isolators or enclosed printed wiring.
MIL HDBK 5400 and NAVSO P-3641 make good reading on power assemblies for hi-rel applications.
Thanks, Wim, it did appear over here. Also got your PM. Sometimes posts propagate onto your ISP's server later than onto other. I've never quite understood why.
Thanks, I'll check that out this afternoon. Hopefully it will be on the web somewhere, I only have the medical IEC/EN standards here on the table. In English and French ;-)
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Regards, Joerg
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That's the problem, we do not have that much real estate here. Otherwise I usually go with medical because it is stricter than pretty much anything else.
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Regards, Joerg
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Yes, but the breakdown curve goes DOWN from sea level to about 30k ft, and then starts going back up. WHich has ABSOLUTELY NOTHING to do with the breakdown in insulation.
Jim
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