The Assignment: Pulling a ground wire

At Zero Gravity Drone, we go beyond just looking and measuring; we also roll up our sleeves. For this project, we were commissioned to pull a shield wire (also known as an earth wire or OPGW).

The shield wire is the topmost cable that connects the peaks of the high-voltage pylons. Its primary function is to protect the current-carrying conductors from lightning strikes by safely directing the current to the ground. Nowadays, these cables often contain fiber-optic connections for data communication between substations. Installing them is traditionally a time-consuming and high-risk task for technicians.

The Unique Challenge: Flying with resistance

The fundamental difference from our regular inspections is the physics of the flight.

• Dynamic Forces: Normally, a drone flies with a static payload (a camera). In this case, we are physically connected to the ground via a cable.

• Drag & Wind: You are not only dealing with the weight of the line but also the resistance from the reel as it unwinds. Additionally, the sagging cable acts as a ‘sail’ that catches the wind. The drone must constantly compensate to stay on course while being continuously pulled.

The solution: M350 with release mechanism

To master these forces, we chose our “tried and tested” DJI Matrice 350. This drone possesses the motor power required to remain stable under heavy load.

The key to success, however, was the modification to the aircraft. We equipped the M350 with an automatic release mechanism. Upon reaching the final position, the pilot can open the clamp via the controller, allowing the line to be released in a controlled manner for the technicians.

The result

The operation was a success: the lines were pulled across safely and quickly, without the need for climbers or heavy cranes in difficult positions. It proves that drones are becoming indispensable in the construction phase of the energy sector.