Aspects Regarding the Surface Temperature for Electric Motors used in Potentially Explosive Atmosphere

Abstract

Most of the equipment operating in potentially explosive atmospheres in oil and gas industry is represented by electric motors, which in most situations act on various other elements (e.g. pumps, valves, fans etc.). Evaluation of explosion-proof protected electrical equipment in scope of certification is extremely important considering the risk of explosion that has to be minimized in order to ensure life safety and health of workers and to prevent damaging of property and the environment, as well as free movement of goods when they meet the essential safety requirements at European level. Even if electric motors for explosive atmospheres are designed and manufactured following some of the same principles as the ones used for other electric machinery, they have certain particularities related to their field of use. Thus, a series of specific restrictions and tests are required to be considered in their case. A very important component on which the explosion protection depends is the surface temperature of the equipment. This is the highest temperature reached in operation under the most unfavorable conditions (but within the tolerances set), by any part or surface of the electrical equipment (in the case of gaseous explosive atmospheres which may occur in technical installations operating in oil and gas industry, this temperature may appear on an internal component or on the outer surface of the case , depending on the type of protection used). To prevent an explosion it is very important that the tests performed on the equipment are done correctly and in the most unfavorable conditions. The purpose of this paper is to present the importance of performing tests to determine the surface temperature for electric motors designed to be used in explosive atmosphere generated by gases and vapors.