To prevent large inrush currents upon application of [+ or -]270-Vdc power to the WACU, the ATRU includes inrush current limiting resistors on the three input power phases.
The high-power connections include the [+ or -]270-Vdc input power from the ATRU and three-phase AC output power to the TM.
In a future implementation, the ATRU can be replaced with an active bidirectional converter for feeding the regenerated power from dynamic braking back to the bus.
Self cooling with dedicated fans for the large components like the ATRU, the WACU, and the TM is probably the most efficient method since the distance between the components is large and an active liquid cooling system is not justifiable
ATRU key requirements Power Input 115Vac, 400Hz, 3 phase, nominal, per ABD 100.