[INTRODUCTION] The voltage within an electrical system can vary depending on the configuration. In a standard scenario, there are two key voltage measurements: “line voltage,” which is the voltage between the live wire and the neutral wire, typically 220 volts, and “phase voltage,” which is the voltage between two live wires, usually 380 volts. This article explores the relationship between line voltage and phase voltage.
[EXPLANATION] To understand the relationship between line voltage and phase voltage, it’s essential to consider the electrical connections in the system. For the star connection configuration, both line voltage and phase voltage are relevant. Line voltage represents the voltage between any two of the live wires, while phase voltage denotes the voltage between a live wire and the neutral point.
In contrast, for delta (angular) connection, there is no neutral point. Therefore, in this setup, phase voltage is equal to line voltage. This occurs because, in angular connection, one of the phase windings is always directly connected between the two live wires, resulting in the lowest standard voltage that the system can handle. In this configuration, line voltage must be equal to phase voltage to ensure the windings’ voltage level is maintained.
For a more comprehensive understanding:
- Three-Phase Electricity: In a three-phase system, three fixed coils within a generator produce induced voltages as they move within a magnetic field. These induced voltages have a phase difference of 120 degrees, commonly referred to as ABC three-phase.
- Neutral Line: In a three-phase four-wire star connection, one neutral wire and three phase wires are present. The neutral line connects to the earth, keeping the neutral point’s potential at zero. This maintains a stable voltage difference between the phase lines (A, B, and C) and the neutral line, which is beneficial for electrical appliances.
- Line Voltage and Current: Line voltage is the voltage between two phase lines, typically 380V, while the current generated by the loop between these lines is called line current.
- Phase Voltage and Current: Phase voltage is the voltage between a phase line and the neutral line, generally 220V. The current generated within this loop is termed phase current.
- Bus: The primary line in a transmission system is known as the bus.
- Relationship: Phase voltage is the voltage between each phase and the ground, while line voltage represents the voltage between phase lines. In a three-phase four-wire system, line voltage is 380 volts, and phase voltage is 220 volts, with a relationship factor of 1.732.
[DIFFERENCE] The difference between line voltage and phase voltage lies in their reference points. Line voltage pertains to the voltage between live wires (380V), while phase voltage concerns the voltage between a live wire and the neutral wire (220V). In star power connections, line voltage is not equal to phase voltage, with the difference being √3 times the phase voltage. In angular power connections, line voltage is equal to phase voltage (380V). Both 380V and 220V systems are used in daily life, with star power connections utilizing a step-down transformer in a three-phase four-wire system.
In a three-phase four-wire distribution system, phase voltage and line voltage can be matched. The voltage between each phase line and the neutral line is called phase voltage, while the voltage between any two phase lines is called line voltage. Phase voltage is typically 220 volts, and line voltage is 380 volts, with line voltage being 1.732 times phase voltage.
It’s important to note that phase voltage and line voltage are defined based on the specific configuration of the electrical system, and their values can vary in different contexts.