Any structure or building or assembly of component parts, whether housed or not, which is intended to generate electrical energy or to convert or transform electrical energy or to change the type of frequency or voltage; except, however, that the Board of Trustees may, in specific cases, grant a permit for the construction of such a structure, building or component parts when and if such Board shall find as a fact, after public notice and hearing, that such a structure, building or component parts is necessary and desirable to improve and increase the efficiency of any electric light and power transportation or like facilities and services rendered to the inhabitants of the Village of Rockville Centre, and that in the proposed location, size and character of construction thereof and its general nature and operation will not be detrimental to the general health and welfare of the community.