How does the CECs' pendulum work?

The pendulum is comprised of three main parts: anchorage with the energy recovery system and stabilizer, on the top part, the steel sphere and the suspension cable.

The cable that suspends the sphere is intertwined steel wire, 4mm in diameter; the sphere is chrome. The sphere is filled with lead and weighs around 100 kilograms.

The energy recovery system returns the energy lost by the pendulum as a result of air friction. If this mechanism did not exist, the pendulun would no longer oscillate after a few hours.

This mechanism is comprised of four optical movement sensors, an electronic control system, an electromagnet (coil) and a magnet. Optical sensors trigger the control circuit that powers the coil located close to the pendulum attachment point.

The magnetic field generated by the coil produces force on the magnet attached to the cable inside the coil. This force compensates air friction enabling the pendulum to oscillate indefinitely.

The stabilization system consists of a metal ring in the upper part of the pendulum, known as the Charron Ring. In its oscillation movement, the cable comes into contact with the inside of the ring. This forces the pendulum to always move on one plane, preventing elliptical oscillation produced by disturbances, such as air currents or vibrations of the building. However, since the cable comes briefly into contact with the Charron Ring in each period, the oscillation plane no longer oscillates in relation to the ground during that period. In consequence, the rotation of the oscillation plane “slows down” and a complete turn takes slightly longer than expected.

The cardinal points and grading that enable measurement of the oscillation plane can be observed at the base.