Altitude de-rating ??

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Jpro556
Forum Member
Posts: 18
Joined: Thu Mar 22, 2018 7:19 pm
My RE system: Two systems:
- Dual Radian 8048's, two FM100's, 10.3kw pv, 12 Simpliphi 3.5's, 1 Kohler 14Resa, 1 Honda EU7000IS
- SystemEdge FP1 3648, FM80, 1 Simpliphi 3.4

Altitude de-rating ??

Post by Jpro556 » Mon Dec 03, 2018 5:14 pm

ANSI says that transformers that use air for insulation or a dielectric(?) have to be de-rated for altitude.

Do radian and FXR inverters need to be de-rated for altitude?

Spec says:
.3% de-rate for every 330ÔÇÖ over 3300ÔÇÖ.
My elevation is 11k. So I might be looking at a 7% de-rating. Round to 10%.

...another factor in system sizing I hadnÔÇÖt considered, if this is a necessary for outback inverters.

Thanks,
Jason

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Gwendoly Espe
Applications Engineering
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Re: Altitude de-rating ??

Post by Gwendoly Espe » Tue Dec 04, 2018 11:05 am

Electrical power systems are affected by altitude. Standards indicate that an electrical device will operate satisfactorily at elevations between sea level and 1000 m. Per the IEEE document VOL. IA-20, NO. 2 a derate factor should be applied on equipment operated above 1000 m.
 Yes, the inverters should be de-rated based on altitude.

http://outbackpower.force.com/articles/ ... al-systems

The manuals only state the maximum altitude. Maximum Altitude Rating 6561ÔÇÖ (2000 m)
Gwendoly Espe
Applications Engineer


Alpha Technologies Inc. / OutBack Power Technologies
3767 Alpha Way Bellingham WA 98226 USA
http://www.alpha.com

JRHill
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Re: Altitude de-rating ??

Post by JRHill » Tue Dec 04, 2018 12:55 pm

Gwendoly Espe wrote:
http://outbackpower.force.com/articles/ ... al-systems

The manuals only state the maximum altitude. Maximum Altitude Rating 6561ÔÇÖ (2000 m)
This is interesting to me. I understand the lower air density would be a negative to cooling. OTOH, unobstructed panels at a high altitude should get better producing sunlight and hence better production. This is location dependent, of course. So, a derated "device" function with better input from the panels... where does this factor out?

The maximum altitude is confusing as well. I can't make sense of that number/elevation. The only thing I can think is that above a certain elevation the power needed for supplemented cooling in thin air is greater than what is gained from doing so.

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