Three-phase circuits are used in transformers, generators, and distributors to generate electric power. It has three voltages interconnected using a star or wye connection or a delta or mesh connection to save copper and make the system less expensive. T
Key Takeaways
- Star connection involves connecting three-phase windings to form a neutral point, while delta connection involves connecting the windings in a triangular shape.
- Delta connection is more suitable for high-power applications, and star connection is more suited for low-power applications.
- The line voltage in the delta connection is higher than the line voltage in the star connection, but the phase voltage in the star connection is higher than in the delta connection.
Star Connection vs. Delta Connection
Star connections are used in long-distance transmission lines, and delta connections are used in short-distance distributed networks. The star connection ufoures 4 wires, three connecting to the external circuit and one to the neutral point. The delta connection uses three wires to form a mesh loop.
The Star connection system connects the starting or finishing ends to the neutral point. It uses four wires to connect to the external load circuit, of which three wires are for the outer course and the fourth fire are for a neutral connection forming a three-phase star connection.
Delta Connection is a system in which the starting end is connected to the phase’s finishing end, forming a mesh loop. A delta-connected system does not have a neutral point.
Comparison Table
| Parameters of Comparison | Star Connection | Delta Connection |
|---|---|---|
| Definition | It is a three-phase four-wire start-connected system used in long-distance power transmission in the distributed network. | It is a three-phase three-wire delta-connected system used in the short-distance transmission of power in the distributed network. |
| Neutral point | It has a neutral point where each resistor’s starting or ending points meet. | There is no neutral point in the delta; instead, the starting point of one resistor is connected to the ending point of the other, forming a mesh loop. |
| Line Voltage | Line voltage = √3 *Phase Voltage | Line voltage is equal to phase voltage. |
| Line Current | Line Current is equal to Phase current. | Line current=√3 * phase current |
| True Power | √3*Line Voltage *Line Current*CosΘ Where Θ is the difference between phase voltage and phase current | √3*Line Voltage *Line Current*CosΘ Where Θ is the difference between phase voltage and phase current |
What is Star Connection?
Star connection is one of the forms to interconnect the three-phase circuit. It has a neutral point N where all the similar ends of the resistors either start or finish joins.
In this system, the line current and line currents are equal. The potential energy at a neutral point is zero.
Formulae
EL (line Voltage) =√3*Eph (phase Voltage) or Eph = EL
Actual power (p) = √3*EL*IL* CosΘ here Θ is the angle obtained between phase voltage and phase current.
Apparent power=√3*EL*IL
What is Delta Connection?
The delta connection is the other form of interconnecting a three-phase circuit. In this circuit, the phases have different ends where the start point of a resistor is connected to the endpoint of the other resistor to form a mesh loop.
The line voltage and phase voltages are equal in the balanced delta-connected system. This system does not have a neutral point. Therefore, only three wires are used in the system.
Formulae
IL (line current) =√3*Iph (phase current) or Iph = IL
Actual power (p) = √3*EL*IL* CosΘ here Θ is the angle obtained between phase current and phase voltage.
Apparent power=√3*EL*IL
Main Differences Between Star Connection and Delta Connection
- The star connection system is a three-phase four-wire system with a neutral point, whereas the Delta connection system is a three-phase three-wire system without a neutral point.
- Star connection systems are used for both low and heavy loads of power transmission long-distance, whereas Delta connection systems are used for heavy load transmission in a shorter distance.
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