The standards in this section apply to: Transformers. (Exclusive of instrument transformers@ auto transfomers used as part of autostarters@ rectifilers@ special testing@ series street lighting@ sign lighting@ ignition@ and radio transformers and all small transformers used for special purposes. Standards for instrument transformers and for constant current transformers and for constant current transformers are the subjects of separate sections. Voltage Regulators. (Exclusive of devices for controlling the voltage of generators).