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56 Technical data
Derating
The load capacity (current and power) decreases if the installation site altitude exceeds
1000 meters (3300 ft), or if the ambient temperature exceeds the nominal ambient
temperature 45 °C (+113 °F).
￭
Temperature derating
Use the following correction factors when you calculate the available inverter station power
at different outdoor temperatures:
•
-20 °C...+20 °C (-4 °F...+68 °F), the power vs temperature ratio is 0 P(%) per 1 °C.
•
+20 °C...+45 °C (+68 °F...+113 °F), the power vs temperature ratio is -0.8 P(%) per
1 °C.
Note:
Temperature ranges are based on assumption +5 °C delta temperature inside the inverter
station.
￭
Altitude derating
The inverter station load capacity (current and power) decreases if the installation site
altitude is higher than 1000 meters (3281 ft). This is due to the fact that air is thinner in
higher elevation which decreases the cooling capacity. To calculate the altitude effect for
installations at higher than 1000 m, add 1 °C per 100 m to the inverter temperature derating
curves (for example, an installation altitude of 1400 m adds 4 °C). When you calculate the
available inverter power, account for the different ratios of P(%) per °C at different inverter
operating temperatures (see section
￭
Combined derating
Because altitude affects the maximum temperature, it is possible to compensate for the
altitude derating value with a limited maximum ambient temperature. Each degree of
maximum ambient temperature below the nominal ambient temperature gives a 1%
compensation to the altitude derating.
Note:
Maximum altitude is limited to 4000 m (13000 ft).
Note:
Use temperature compensation only for altitude derating. Nominal power must not be
exceeded.
Derating Example
This example calculation is for a site at 1300 m with an ambient temperature of 35 °C:
1. Calculate the altitude corrected temperature: 35 °C + 3 °C = 38 °C.
2. Calculate the inverter power difference with relation to the nominal (+45 °C) value with
the altitude corrected temperature: (45 °C – 38 °C) * 0.8 P(%)/°C = 5.6 P(%).
3. Add the result to the inverter nominal power (100 P(%)): 100 P(%) + 5.6 P(%) = 105.6
P(%).
4. Based on the calculation, in these conditions the inverter can produce 105.6% of its
nominal power.
In the unlikely event that the total equivalent temperature (site °C + altitude °C) exceeds
the nominal temperature of 45 °C, contact ABB for information.
Temperature derating (page
56)).
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