Designing Transformers for the Power Supply of a Transmission Line Inspection Robot

September 1800

This work describes the design and the prototype essays of power transformers to be part of a power supply system that grabs energy from power line cables to supply line inspection robots. The power levels obtained are compatible with the robot power needed when using a carefully designed energy management system. Two variants of the designed transformer, based on UI or UU laminations, denoted respectively TUI and TUU, are presented in the paper along with a discussion on limitations and possible improvements. The basic design principle to harvest the magnetic energy requires a magnetic core surrounding the power cable which acts as a single turn primary winding of a transformer. The secondary is coiled around the core. The typical range of line currents to be considered for the operation of the transformer lies between 100 and 1000A, with the transformer itself having almost no influence in this current. The line current variation must be accounted for in the power converter stage that interfaces the transformer from the robot, by making the transformer supplying a slowly varying resistive load [2,3]. The power cable cylindrical structure leads naturally to a toroidal shape for the transformer core. With a primary winding section around 500 mm2 (the typical section area of a high voltage power line) the toroid inner window must accommodate the power cable and the secondary winding, while allowing some margin for isolation. The prototypes developed use off-the-shelf UI and UU cores instead. The resulting transformers show very interesting measured power outputs of 600W (TUI) and 290W (TUU), respectively at 300A and 350A line currents. Such power levels clearly indicate that this type of power supply is indeed a valid option that can still be improved by selecting adequate toroidal cores and tuning the design parameters.

Authors in the community:

• 

  J

  José Fernando Alves da Silva

  ist11962

• 

  J

  João Fernando Cardoso Silva Sequeira

  ist13132

Procs. 7th Annual CIGRÉ Canada Conference on Power Systems

Montreal

electrical-engineering-electronic-engineering-information-engineering - Electrical engineering, electronic engineering, information engineering

eng - English