Adapted from CIM data models. The class represents IEEE Std 421.5-2005 type ST1A model. This model represents systems in which excitation power is supplied through a transformer from the generator terminals (or the unit’s auxiliary bus) and is regulated by a controlled rectifier. The maximum exciter voltage available from such systems is directly related to the generator terminal voltage. Reference: IEEE Standard 421.5-2005 Section 7.1.