Line and phase quantities differ by √3 in balanced three-phase systems.
In wye, V_L=√3 V_ph and I_L=I_ph; in delta, V_L=V_ph and I_L=√3 I_ph. Wye has a neutral and lower phase voltage; delta tolerates a lost transformer in open-delta. Motor starting uses star-delta switching.
A motor rated for 400 V delta runs from 690 V in star.
Star and delta connections determine the voltage and current in each winding, which affects how a motor or load is wired to the supply.
Line and phase quantities differ by √3 in balanced three-phase systems.
Star and delta connections determine the voltage and current in each winding, which affects how a motor or load is wired to the supply.
In a balanced star, the line voltage equals the square root of three times the phase voltage.
The line current equals the square root of three times the phase current in a balanced delta, while the line voltage equals the phase voltage.
Typical applications include choosing a star or delta connection for a motor on a given supply voltage, calculating the line current drawn by a delta-connected heater and checking the voltage across a single winding in a star-connected transformer.
Study "Three-phase systems" first (topic 53 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
Line vs phase quantities. Delta circulating harmonics. Zig-zag grounding transformers.
A motor rated for 400 V delta runs from 690 V in star.
The next topic is "Three-phase power measurement", which builds directly on this one.
It is classed as Intermediate in Electrical Engineering (topic 54 of 106). It is an intermediate topic. Work through the beginner topics in Electrical Engineering first.
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