IEEE Std C37.100.1-2018 pdf download – IE EE Standard for Common Requirements for High-Voltage Power Switchgear Rated Above 1000 V.
a) The ambient air temperature does not exceed 40 °C. The minimum ambient air temperature is – 30 °C for class“minus 30 indoor. b) The influence of solar radiation may be neglected. c) The altitude does not exceed 1000 m above sea level. (Switchgear ratings are based on sea level. See Annex B for considerations at application above sea level.) d) The ambient air is not significantly polluted and would be classified as having pollution level I “light” according to Table C.1 in Annex C. e) The conditions of humidity are as follows: 1) The average value of the relative humidity, measured over a period of 24 h, does not exceed 95%. 2) The average value of the relative humidity, over a period of one month, does not exceed 90%. For these conditions, condensation may occasionally occur. NOTE 1–Condensation can be expected where sudden temperature changes occur in periods of high humidity. NOTE 2- To withstand the efects of high humidity and condensation, such as breakdown of insulation or corrosion of metallic parts, switchgear designed and tested for such conditions should be used. NOTE 3- Condensation may be prevented by special design of the building or housing, by suitable ventilation and heating of the station or by the use of dehumidifying equipment. Other options include heaters with thermostats/ humidistat inside the switchgear. Condensation may also be due to ground level . rainwater or for underground applications, from incoming cable raceways connected to switchgear. f) Vibration due to causes external to the switchgear and controlgear or earth tremors are insignificant relative to the normal operating duties of the equipment and do not exceed the low performance level defined in IEEE Std 693. 10 The manufacturer will assume that, in the absence of specific requirements from the user, there are none.