Adapted from CIM data models. The class represents IEEE Std 421.5-2005 type AC7B model. The model represents excitation systems which consist of an ac alternator with either stationary or rotating rectifiers to produce the dc field requirements. It is an upgrade to earlier ac excitation systems, which replace only the controls but retain the ac alternator and diode rectifier bridge. Reference: IEEE Standard 421.5-2005 Section 6.7. In the IEEE Standard 421.5 – 2005, the [1 / sT] block is shown as [1 / (1 + sT)], which is incorrect.