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):
- 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.
- 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:
- Insulation technology for 525 kV HVDC must withstand extreme electric field stress without breaking down.
- 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.










