Application: SCR-controlled Battery Charger.
Input power: 440 VAC, 60 Hz, 3 ph, 3-wire, 10 KW.
Output power: 42.3 VDC, 200 Amps.
Input Transformer: 440V pri. Δ, 44V sec. Y, 18-pulse (9-phase).
Links shows sketch of application and transformer winding configuration.
Link
I thought the 18-pulse...