The construction of the ST& STC series alternators is of drip-proof, salient pole rotating field self-excitation and constant voltage type. The alternator is used with high quality electric magnetic and electrical materials inside. Stator and Rotor insulation is of Class B. These alternators are excellent in appearance. The dimensions are adopted IEC standard. The alternators are of harmonic wave self-excitation constant voltage system and automatic voltage control excitation constant voltage system.