The a.c. the armature winding can be either star (Y) connected or delta (Δ) connected, depending on the specific design requirements and operating conditions of the alternator.

Star (Y) connection is commonly used in low voltage alternators where the line voltage is equal to the phase voltage. In this configuration, the ends of the three winding coils are connected together to form a common neutral point, which is then connected to the system neutral or ground. The line voltage is measured between the phase terminals and the system neutral, while the phase voltage is measured between any two phase terminals.

Delta (Δ) connection is typically used in high-voltage alternators where the line voltage is greater than the phase voltage. In this configuration, the winding coils are connected in a closed loop, with each coil connected to the next in a series. The line voltage is measured between any two phase terminals, while the phase voltage is equal to the line voltage divided by the square root of three.

The choice of winding connection depends on various factors, such as the required output voltage, the number of phases, and the operating conditions of the alternator.