When it comes to connecting a 3-phase power supply, two common methods are the star (or wye) connection and the delta connection. Both methods have their own advantages and applications, so it's important to understand the differences between them. One of the fundamentals in electrical engineering is understanding how 3-phase systems are connected: Star (Y) or Delta (Δ). Both are widely used, but in different ways.
Star (Y) Connection
- Neutral is available → can supply both 3-phase and single-phase loads.
- Line voltage = √3 × phase voltage (higher line voltage).
- Commonly used for long-distance transmission because it reduces insulation requirements.
- Starting current is lower → good for starting heavy motors in star before switching to delta.
Delta (Δ) Connection
- No neutral point (only 3 wires).
- Line voltage = Phase voltage (higher current flow).
- Provides higher starting torque → often used for distribution and running of heavy motors.
- More robust, can keep running even if one phase goes down (open delta).
Rule of thumb:
Star → Best for transmission & mixed (3-phase + single-phase) loads.
Delta → Best for distribution & running heavy 3-phase machines.
A star connection is commonly used in systems where the load is evenly distributed among the three phases. This configuration is ideal for systems with mixed resistive and inductive loads. On the other hand, a delta connection is preferred for systems with mostly high-power loads or for applications where a higher line voltage is required.