- 2068 Shrawan · 4 marks
Compare star and delta connection
Short answer
Star: V_L=√3 V_ph, I_L=I_ph, neutral available. Delta: V_L=V_ph, I_L=√3 I_ph, no neutral. Both deliver same total power √3 V_L I_L cos φ in balanced conditions.
Compare the star and delta 3 phase connection.
| Basis | Star (Y) connection | Delta (Δ) connection |
|---|---|---|
| Connection | Similar ends of the three windings joined at a neutral point | End of each winding joined to the start of the next, forming a closed loop |
| Line voltage | V_L = √3 V_ph | V_L = V_ph |
| Line current | I_L = I_ph | I_L = √3 I_ph |
| Neutral | Available (3-phase 4-wire possible) | Not available (3-wire only) |
| Phase voltage | Lower (V_L/√3), so less insulation needed | Equal to line voltage |
| Phase current | Equal to line current | I_L/√3 |
| Power (balanced) | √3 V_L I_L cos φ | √3 V_L I_L cos φ |
| Use | Transmission and distribution (supplies both 230 V and 400 V); motor starting in star–delta starters | Running windings of induction motors; HV (primary) winding of distribution transformers |
| Unbalanced loads | Neutral carries the unbalanced current | No neutral; unbalanced loads give unequal line currents (third-harmonic currents circulate inside the delta) |
✓ Answer checked by Claude Opus 5.5 (high effort)
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