Do Power Transmission Lines Have a Magnetic Field?

Most power transmission lines worldwide use a three-phase system. They have three wires, each carrying an alternating current that's out of sync with the others by 120 degrees.

Ideally, transmission power lines are in a balanced 3-phase system, meaning each wire carries the same amount of current. So, the magnetic fields from each wire largely cancel each other out.

This is because the sum of the currents in the three phases is always zero at any given moment.

When one phase is at its peak, the other two are at -50% of the peak, resulting in a significant, though not complete, cancellation of magnetic fields.

Overall, the sum of instantaneous values of three phases in balanced three phase system is always ZERO.

I talked about the peak values comparison and explain it with a waveform below, because it is easy to pick it 😄

However, in the real world, this cancellation isn't perfect. The wires are separated by some distance), and the currents aren't always perfectly balanced.

So, there is still some magnetic field around power lines, but it's much weaker than it would be with a single-phase system.

This partial cancellation of magnetic fields is one reason why three-phase systems are widely used for power transmission. They're more efficient and produce less electromagnetic interference than other systems.