What is phase voltage, and what is line voltage? These two terms are often confused, but they have clear differences. This article will explain both concepts in detail.
In a three-phase system, there are two common configurations: delta and star (wye). In a delta connection, there are three live lines with no neutral wire, and the voltage between any two lines is called the line voltage, which is typically 380V. In a star connection without a neutral, the same applies. However, when a neutral wire is present, it becomes a three-phase four-wire system. In this case, the voltage between a live line and the neutral is known as the phase voltage, which is usually 220V. The line voltage remains 380V, and it is the vector sum of two phase voltages. Mathematically, the relationship is: Line Voltage = √3 × Phase Voltage. So, 380V = √3 × 220V.
Many people mistakenly believe that the phase voltage is 380V and the line voltage is 220V, which is the opposite of the actual definition. Understanding the difference is crucial for electrical safety and proper system design.
**Concepts:**
Phase voltage refers to the voltage measured between a live line and the neutral line, which is typically 220V in household settings. All the electricity used in homes comes from this phase voltage. On the other hand, line voltage is the voltage between any two live lines in a three-phase system, commonly 380V. This is often referred to as the "line-to-line" voltage.
**Relationship and Differences:**
During long-distance power transmission, higher voltages reduce energy loss, which is why high-voltage transmission lines are used. Once the electricity reaches the end-user, transformers step down the voltage to 220V or 380V for different applications.
In a three-phase four-wire system, the phase voltage is measured between each live wire and the neutral, while the line voltage is measured between any two live wires. The three-phase voltages are out of phase by 120 degrees. The line voltage is calculated using vector addition, resulting in a value equal to √3 times the phase voltage.
When a motor operates with only two phases, it can still run, but this is known as "phase loss." It can lead to overheating and damage. In a delta-connected motor, losing one phase reduces its output power by about two-thirds, causing unbalanced currents and potential burnout. Similarly, in a star-connected motor, losing a phase causes the remaining windings to carry more load, increasing the risk of failure.
If a three-phase motor loses two phases, it may not start at all. For a single-phase motor connected to a 380V supply, the voltage would be too high, leading to immediate damage.
Understanding the difference between phase and line voltage is essential for safe and efficient use of electrical systems. Whether you're working on motors, wiring, or just trying to understand your electricity bill, knowing these basics can help prevent costly mistakes.
Digital Signage Outdoor,Digital Advertising Boards,Display Digital Signage,Healthcare Digital Signage
Guangdong Elieken Electronic Technology Co.,Ltd. , https://www.elieken.com