1. What does △/Y0-11 mean on the transformer nameplate? Answer: According to the different connection methods of the primary coil and the secondary coil of the transformer, the phase angle of the line voltage on the primary side and the secondary side of the transformer is different. Transformer △/ Y0-11 means that the phase angle difference between the two line voltages of the transformer is 330°. It is customary to use the clock notation, that is, 11 o'clock.