IEEE (2005) DC4B Model<br /></p><p><br /></p><p>These excitation systems utilize a field-controlled dc commutator exciter with a continuously acting voltage<br /></p><p>regulator having supplies obtained from the generator or auxiliary bus. The replacement of the controls only<br /></p><p>as an upgrade (retaining the dc commutator exciter) has resulted in a new model. This excitation system typically includes a proportional, integral, and differential (PID) generator voltage regulator (AVR). An alternative rate feedback loop (kf, tf) for stabilization is also shown in the model if the AVR does not include a derivative term. If a PSS control is supplied, the appropriate model is the Type PSS2B model.<br /></p>