IEEE (1992/2005) DC3A Model<br /></p><p><br /></p><p>The Type DC3A model is used to represent older systems, in particular those dc commutator exciters with non-continuously acting regulators that were commonly used before the development of the continuously acting varieties. These systems respond at basically two different rates, depending upon the magnitude of voltage error. For small errors, adjustment is made periodically with a signal to a motor-operated rheostat. Larger errors cause<br /></p><p>resistors to be quickly shorted or inserted and a strong forcing signal applied to the exciter. Continuous<br /></p><p>motion of the motor-operated rheostat occurs for these larger error signals, even though it is bypassed by<br /></p><p>contactor action. <br /></p>