High-temperature derating of power frequency online UPS is based on 40℃ as the upper limit of rated power in the national standard, and 10%~20%** for every 5℃ increase above 40℃, and 55℃ as the long-term operation limit.
I. Basis of National Standard (GB/T 7260.40-2020)
Normal temperature:-5℃ ~ 40℃, 20℃ ~ 25℃ is the best, and it can be fully loaded.
Long-term high temperature (40℃ ~ 55℃): operation is allowed, but the rating must be reduced; Long-term operation is prohibited above 55℃.
Short-term limit: 40℃ ~ 55℃ ≤72 hours per month, which needs to be equipped with enhanced heat dissipation and wide temperature battery.
Second, the general derating standard (industry consensus)
40℃: 100% rated power (no derating).
45℃: * * 80% ~ 90% * * Rated power (10% ~ 20% drop every 5℃).
50℃: * * 60% ~ 80% * * rated power.
55℃: * * 50% ~ 60% * * rated power (long-term limit).
> 55℃: operation is prohibited, and shutdown of over-temperature protection is triggered.
Third, the mainstream manufacturers reference (power frequency online)
Schneider: linear derating from 40℃, 2.5% for every 1℃ increase; 45℃≈87.5%，50℃≈75%。
Huawei: 10% drop at 40℃ ~ 45℃ (45℃ ≈ 90%); At 45℃ ~ 50℃, the temperature will drop by 10%(50℃≈80%).
Shante/Kehua: 15% for every 5℃ above 40℃; 45℃≈85%，50℃≈70%。
IV. Reasons for derating (characteristics of power frequency machine)
Transformer: The power frequency machine is equipped with a high-power transformer, which has limited insulation (F-class 155℃/H-class 180℃) and iron loss at high temperature.
Power devices: the upper limit of junction temperature of IGBT and rectifier bridge is about 150℃, and high temperature is easy to trigger overcurrent/overtemperature protection.
Electrolytic capacitor: the service life of 105℃ capacitor is halved for every 10℃ increase, and it is easy to bulge and leak at high temperature.
Battery: The life of lead-acid battery drops sharply above 40℃, and 55℃ is the charging limit.
V. Operation and maintenance suggestions
Environmental control: the temperature of the machine room is **≤35℃**, the humidity is 40% ~ 60%, and there is no condensation.
Load management: the load rate above 40℃ * * ≤ 80%; Above 45℃ ≤60%**.
Heat dissipation enhancement: clean the filter screen to ensure the smooth air duct; In outdoor/high temperature environment, choose liquid-cooled or H-class insulation model.
Six, fast memory table
form
Ambient temperature allowable output power operation limit
100% long-term full load at ≤ 40℃
80% ~ 90% long-term derating at 40 ~ 45℃
60% ~ 80% long-term derating at 45 ~ 50℃
50 ~ 55℃ 50% ~ 60% Short-term (month ≤72h)
> 55℃ 0% operation is prohibited.
