Primary Coil : (Elec. Eng. A coil, forming part of an electrical machine, or piece of apparatus, in which flows a current setting up the magnetic flux necessary for the operation of the machine or apparatus. (Chambers)
H. J. Porter (Chairman - Technical Committee), Dictionary of Fire Technology, The Institution of Fire Engineers, The Victory Press (Leicester) Ltd. 1979 UK. (Fr Tech - Brit) {81}