To process application software, two independent Universal Controller Stand-alone Board

Version B (UCSB) controllers, with separate PCMs and an output selector module (SCM

or TCM), provide the dc output current for the exciter field (or SCTcontrol winding).

The active power bridge receives the gating commands from the active control (M1 or

M2), and supports the full-field voltage and current needs of the exciter field while the

backup power bridge’s gating circuit is inhibited. The operator has full control to select

which of the dual power bridges is active or inactive. Bi-directional, bumpless transfer

between active and inactive bridges is standard. The active master can also self-diagnose

a failure or missed operation and activate the backup control and power bridge without

operator intervention.

The control includes M1 (Master

One) and M2 (Master Two), with two IGBT bridges that can accept separate or shared ac

input power. The control configuration can also share a common dc output circuit to the

exciter field through the transfer module. M1 and M2 are independent controls, each with

automatic and manual regulator functions. Either M1 or M2 can control bridge firing, as

determined by the operator.