22 July 2019

Advantages and disadvantages of star and delta connection

A star-delta starter is the most commonly used method for the stating of 3 phase induction motor. In star connection, the starting or finishing ends of three coils are connected together to form the neutral point. A common wire is taken out from the neutral point which is called neutral while in delta connection the opposite end of three coils is connected together. Here this page gives information about the pros and cons of star and delta connection to better understand this topic.

Advantages of star connections:
  • Used for high voltage
  • Common neutral point
  • Good for unbalanced loading
  • Each phase is a separate circuit
  • Dual voltage applications 
  • Star connection can distribute the load evenly
  • Star connection alternator requires lesser insulation
  • Star connection alternator requires a lesser number of turns than delta for the same voltage
  • Ability to spread the load between the phases
  • Availability of single phase at a lower voltage
  • The neutral point can be earthed

Disadvantages of star connections:
  • Less torque
  • Construction involves combining 3 single phases into 1
  • Secondary distribution, light-duty applications
  • Construction cost is more expensive

Advantages of delts connections:
  • More torque
  • Efficient
  • Simple motor design
  • Heavy-duty application
  • Protection is simple and less costly
  • Used in rotatory conveyors
  • While use delta connection, less current per winding for the same power output
  • Major applications in power generation, transmission, and distribution
  • The transformer secondary provides all the 3 phases
  • Construction cost is low

Disadvantages of Delta connections:
  • No common neutral point
  • Detecting earth ground faults is difficult
  • Low voltage connection

Summary : 

If power is kept constant, delta connection has lower voltage and high current capacity whereas a star connection has higher voltage and low current capacity.