The IS200ERDDH1A model is part of the EX2100 series and is an Exciter Regulator Dynamics Discharge Board. The ERDD model has two operating modes, simplex and redundant. Each application mode is used differently as well as mounted differently.
When the IS200ERDDH1A is being used in simplex mode the model controls the K3 charging relay; when the board is being used in the redundant mode it will control the K41 de-excitation relay. The mounting places of the ERDD mode when operating in simplex and redundant mode are different, when in simplex mode the IS200ERDDH1A is mounted in the ERBP backplane and when in redundant mode two ERDD models must be used, one is mounted in the same location as the model in simplex mode and the other board will be mounted in the ERRB backplane.
Another function of the board is to provide feedback from the bridge to observe the output field and DC link voltages. When monitoring these the board also allows for observation of output shunt currents, IGBT gate drive statuses, and bridge temperature. The IS200ERDDH1A board is also typically used to control the excess DC link voltages through the dynamic discharge of the model.