What is a Star connection?
A star connection, also known as a wye connection, is a type of electrical connection in which all of the terminals of a three-phase system are connected to a common point, forming a star shape. This common point is sometimes referred to as the "star point" or the "neutral point."
What is Delta Connection?
In a delta connection, also known as a delta connection, the three terminals of a three-phase system are connected together in a closed loop, forming a triangle shape. There is no common or neutral point in a delta connection, and all three phases are connected in series.
Delta connections are often used in electrical power transmission and distribution systems for short distances, because they allow for the transmission of electrical power at high voltages with a minimal amount of conductor material. Delta connections are also used in electrical motors because they allow for a more balanced distribution of the electrical current, which can help to reduce electrical losses and improve the efficiency of the motor.
Difference Between Star and Delta Connection
| Property | Star Connection | Delta Connection |
|---|---|---|
| Basic definition | Terminals connected to a common point | Branches connected in a closed loop |
| Terminal connection | Similar ends of the three coils connected together | Opposite terminals of the coils connected together |
| Neutral point | Neutral point exists | Neutral point does not exist |
| Line/phase current | Line current equals phase current | Line current equals root three times phase current |
| Line/phase voltage | Line voltage equals root three times phase voltage | Line voltage equals phase voltage |
| Motor speed | Slow (receives 1/√3 of the voltage) | Fast (each phase receives full line voltage) |
| Phase voltage | Low (1/√3 times line voltage) | Equal to line voltage |
| Number of turns | Fewer turns required | More turns required |
| Insulation level | Low | High |
| Network type | Power transmission networks | Power distribution networks |
| Voltage received by each winding | 230 volts | 414 volts |
| Type of system | 3 phase 4 wire, 3 phase 3 wire | 3 phase 4 wire |
Difference Between Star and Delta Connection
- In a star connection, the terminals of the three branches are connected to a common point, forming a network. In a delta connection, the three branches are connected in a closed loop.
- In a star connection, the starting and ending points of the three coils are connected to a common point called the neutral point. In a delta connection, there is no neutral point, and the opposite terminals of the coils are connected together.
- The line current in a star connection is equal to the phase current, while in a delta connection the line current is equal to the square root of three times the phase current.
- The line voltage in a star connection is equal to the square root of three times the phase voltage, while in a delta connection the line voltage is equal to the phase voltage.
- The speed of motors connected in a star configuration is slower because they receive 1/√3 of the voltage, while motors connected in a delta configuration run faster because each phase receives the full line voltage.
- Star connections are mainly used in power transmission networks for longer distances, while delta connections are mainly used in distribution networks for shorter distances.
- In a star connection, each winding receives 230 volts, while in a delta connection each winding receives 415 volts.
- Both 3 phase 4 wire and 3 phase 3 wire systems can be derived in a star connection, while only 3 phase 4 wire systems can be derived in a delta connection.
- A star connection requires less insulation, while a delta connection requires a higher level of insulation.
There are several differences between star and delta connections:
Phase voltage: In a star connection, the phase voltage is equal to the voltage between each winding end and the neutral point. In a delta connection, the phase voltage is equal to the voltage between any two winding ends.
Line voltage: In a star connection, the line voltage is equal to the phase voltage. In a delta connection, the line voltage is equal to the phase voltage multiplied by the square root of 3 (√3).
Current: In a star connection, the current in each winding is equal to the phase current. In a delta connection, the current in each winding is equal to the phase current divided by the square root of 3 (1/√3).
Power: In a star connection, the power in each winding is equal to the phase power. In a delta connection, the power in each winding is equal to the phase power multiplied by the square root of 3 (√3).
Neutral point: A star connection has a neutral point, which is a common point where the three winding ends are connected. A delta connection does not have a neutral point.
Impedance: The impedance of a star connection is higher than the impedance of a delta connection, because the neutral point provides an additional path for current to flow.