Reint Jelger (about power transmission cables): So you are saying with 525kV there is less line loss

Gemini: Yes, exactly. Counterintuitively, the higher the voltage, the lower the loss over long distances.

This comes down to a fundamental law of electrical physics (P=I2R).

When electricity flows through a metal conductor (like copper or aluminum), the electrical current encounters natural resistance (R). That resistance converts part of the electrical energy into waste heat.

The formula for power loss (Ploss​) in a conductor is:

Ploss​=I2⋅R

Where:

• I = Current (Amperes / Amps)
• R = Resistance of the cable (Ohms)

Notice that current (I) is squared. If you double the current running through a cable, you don’t double the heat loss—you multiply it by 4 times. If you increase current by 10 times, heat loss increases by 100 times.

Why 525 kV Changes the Game

Total electrical power (P) being moved down the cable is:

P=V⋅I

Where:

• V = Voltage (Volts)
• I = Current (Amps)

To move a massive amount of power across a continent (say, 1,000 Megawatts from a North Sea wind farm to an industrial district):

1. Option A (Low Voltage, High Current): If you keep voltage low, you have to push a massive current (I) through the wire. Because of I2R, the cable gets extremely hot, melts its insulation, and loses a huge percentage of the electricity as heat before it reaches its destination.
2. Option B (High Voltage, Low Current – 525 kV): By stepping the voltage up to an extreme 525,000 Volts, you can move the exact same total power using a tiny current (I). Because I is now very small, I2R heat loss drops dramatically.

HVDC (Direct Current) vs. AC Over Long Distances

At 525 kV, long-distance lines almost always use High Voltage Direct Current (HVDC) rather than standard Alternating Current (AC).

• The AC Limitation: Alternating current continuously changes direction (50 times per second in Europe). Over long insulated cables (especially underwater), AC creates a heavy electromagnetic effect called capacitive charging loss, where the cable behaves like a giant capacitor and consumes its own power.
• The HVDC Advantage: Direct current flows continuously in one direction. There is no capacitive loss, meaning power can be pushed over 1,000+ kilometers of continuous subsea or underground cable with line losses as low as 3% to 4% per 1,000 km.

The Industrial & Business Takeaway

This physical reality is why companies like Prysmian and Nexans command high profit margins:

1. Insulation technology for 525 kV HVDC must withstand extreme electric field stress without breaking down.
2. Manufacturing a continuous conductor that can handle these stresses over hundreds of kilometers without a single structural flaw is a massive technical barrier to entry.