Question

What is the relation between star delta current and voltage?

Answer 1

In a three-phase electrical system, star (Y) and delta (Δ) connections are two common ways of connecting loads or generators. The relationship between the current and voltage in star and delta connections differs, and here's how:

1. Voltage Relationship:

   - Star Connection (Y):
     In a star connection, the line voltage (voltage between two phases) is √3 times the phase voltage (voltage between a phase and neutral).  
     \[
     V_{\text{Line}} = \sqrt{3} \times V_{\text{Phase}}
     \]
     So, the line voltage is higher than the phase voltage by a factor of √3.

   - Delta Connection (Δ):
     In a delta connection, the line voltage is equal to the phase voltage.  
     \[
     V_{\text{Line}} = V_{\text{Phase}}
     \]

2. Current Relationship:

   - Star Connection (Y):
     In a star connection, the line current (current in the wire between the phases) is equal to the phase current (current flowing through each individual load).  
     \[
     I_{\text{Line}} = I_{\text{Phase}}
     \]
   
   - Delta Connection (Δ):
     In a delta connection, the line current is √3 times the phase current (current flowing through the load).  
     \[
     I_{\text{Line}} = \sqrt{3} \times I_{\text{Phase}}
     \]

Key Points:

1. Voltage: Line voltage is higher in star (√3 times phase voltage) and equal in delta (line voltage = phase voltage).
   

1. Current: Line current is equal to phase current in star connection and √3 times the phase current in delta connection.
   

In short, in a star connection:

1. Line voltage = √3 × Phase voltage
   

1. Line current = Phase current
   

In a delta connection:

1. Line voltage = Phase voltage
   

1. Line current = √3 × Phase current
   

This relationship helps engineers understand how voltage and current behave in different wiring setups, affecting things like power, efficiency, and safety in electrical systems.