Example – temperature derating calculation for a TRIO-20.0/27.6-TL-US installed at 7500 feet:
• The maximum rated temperature, for full power operation at sea level, from the TRIO-20.0/27.6-TL-US series
datasheet, is 113°F (45°C).
• The normalized temperature derating factor from the graph on page 97, at an altitude of 7500 feet is .945.
• The maximum full-power temperature for operation at 7500 feet would be 113°F * .945 = 107°F --OR-- 45°C
* .945 = 42.5°C.
Voltage derating
The dielectric strength of air decreases with altitude, so the maximum DC input inverter voltage must be decreased
at high altitudes to avoid unwanted electrical arcs. The graph below shows normalized voltage derating factor with
increased altitude.
Automatic power reduction
In order to maintain safe inverter operation under adverse environmental conditions or due to improper input
voltages, the unit automatically reduces the amount of power it feeds to the grid. The conditions for power reduction
due to environmental conditions and input voltage can occur at the same time, but the power reduction will always
be determined by the more severe factor.
50
55
60
65
70
75
80
85
90
95
100
1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000
% Maximum Input Voltage (V)
Altitude (feet and meters)
Altitude vs max input voltage
3280 3937 4593 5249 5905 6561 7217 7874 8530 9186 9842
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