I was conducting some robotics tests on a old wind turbine today, and noticed strong magnetic fields around the steel tower. This magnetic field does not exist on other modern wind turbines at the same site. I am completely baffled by this, so I’m hoping I can find some answers here.
These turbines are located in San Gorgonio Path near Palm Springs, CA. They are Nordtank 65 wind turbines, decommissioned about a decade ago. The towers are steel, bare, without paint. Overall they have very little rust as the climate is very dry and hot. The turbines still contain their generators, which contain magnets. But I don’t think these magnets are very strong.
Using a decent mechanical compass, I can clearly see about 40 degrees of deflection as I walk towards the base of the tower from about 10 feet away. I tried this on all 6 decommissioned Nordtanks, all of them exhibited the same behavior. I tried on modern 0.5 MW turbines nearby while they are generating, but the max compass deflection I got was about 5 degrees at a distance about 5 inches away from the tower itself.
When I first observed the magnetic field, my theory was that the turbine tower was still heating up from the morning sun. Due to Seebeck effect, there could be current flowing in the material as the base is cooled by the foundation buried into the ground. However the deflection on the compass did not stop even though the temperature stabilized.
What could have caused this? I would love to find out!