IEEE Std C37.74-2014 pdf download – IEEE Standard Requirements for Subsurface, Vault, and Padmounted Load-Interrupter Switchgear and Fused Load-Interrupter Switchgear for Alternating Current Systems up to 38 kV.
4.1.2 Outdoor DSG Subclause 2.1.2 of IEEE Std C37.100.1-2007 applies. 4.2 Special (unusual) service conditions Subclause 2.2 of IEEE Std C37.100.1-2007 applies with the following addition:  Any unusual service conditions should be specified by user. 4.2.1 Altitude Subclause 2.2.1 of IEEE Std C37.100.1-2007 applies. 4.2.2 Exposure to excessive pollution Subclause 2.2.2 of IEEE Std C37.100.1-2007 applies. 4.2.3 Temperature and humidity Subclause 2.2.3 of IEEE Std C37.100.1-2007 applies with the following modifications:   When DSG is applied where the ambient air temperature is higher than 40 ºC, the total temperature limits for parts and materials as listed in 5.5 should not be exceeded. Therefore, for the higher ambient, the equipment should be derated to a continuous current value that maintains the total temperature limits.   When DSG is applied where the ambient air temperature is less than −30 ºC, space heating and thermal insulation should be considered to minimize the effects of such exposure.
4.2.4 Exposure to abnormal vibration, shock, or tilting Subclause 2.2.4 of IEEE Std C37.100.1-2007 applies. 4.2.5 Other special (unusual) service conditions Subclause 2.2.5 of IEEE Std C37.100.1-2007 applies. 4.2.5.1 Exposure to damaging fumes, vapor, steam, oil vapors, salt air, and hot and humid climate Subclause 2.2.5.1 of IEEE Std C37.100.1-2007 applies. 4.2.5.2 Exposure to excessive dust or abrasive, magnetic, or metallic dust Subclause 2.2.5.2 of IEEE Std C37.100.1-2007 applies. 4.2.5.3 Exposure to explosive mixtures of dust of gases Subclause 2.2.5.3 of IEEE Std C37.100.1-2007 applies.
5.2.1.3 Rated lighting impulse withstand voltage (U p ) The rated lightning impulse withstand voltage shall be the voltage of the way with the lowest rating. The preferred values of rated lightning impulse withstand voltage are shown in Column 4 of Table 1. 5.2.1.4 Rated power-frequency withstand voltage (U d ) The rated power-frequency withstand voltage shall be that of the way with the lowest rating. The preferred values of rated power-frequency withstand voltage are those shown in Column 5 of Table 1. 5.2.1.5 Rated short-time withstand current and duration (I k ) (t k ) The rated short-circuit withstand current shall be the lowest of the following ratings of any of the ways and shall be expressed in both short-time withstand and peak withstand current. a) The rated interrupting current of the protective devices (if applicable). b) The rated peak withstand and short-time current of the switches, loadbreak devices (if applicable), grounding switches (if applicable), and bus. c) The rated fault-making current of the switches, loadbreak devices, protective devices, and grounding switches (if applicable).