Linetolinespänningar

Lineto-linespänningar, a term used in Swedish to describe the voltage difference between any two conductors in a multi-line electrical system, are the voltages that power equipment connected across two lines. They are essential for equipment such as motors, transformers, and other line-connected devices.

In a balanced three-phase system, the three line-to-line voltages are equal in magnitude and separated by 120 degrees. The line-to-line voltages are typically denoted V_AB, V_BC, and V_CA. The relationship to the line-to-neutral (phase) voltages V_LN is V_LL = sqrt(3) × V_LN in a wye (star) connected system. For example, a system with 230 V line-to-neutral yields about 400 V line-to-line in many European standards (V_LL ≈ 1.732 × V_LN). In delta connections, the line-to-line voltages are equal to the phase voltages, so V_LL corresponds directly to the system’s phase voltages.

The line-to-line magnitude is the vector difference between two phase voltages, and remains defined for unbalanced or non-sinusoidal conditions as the instantaneous or RMS value between two lines. In practice, ratings for equipment such as motors and transformers are often given as line-to-line voltages (e.g., 208 V, 400 V, 480 V), reflecting the standardized voltages used between lines rather than line-to-neutral values.

Measurement between two lines yields a line-to-line value, requiring appropriate safety and isolation precautions. Understanding lineto-linespänningar is fundamental for correctly sizing equipment, ensuring compatibility with supply voltages in different regions, and performing accurate electrical design and analysis.