Support of guyed transmission tower, using self-adjusting sprung guy wires
Johnston, A. Grant
Manitoba Hydro transmits high-voltage electric power hundreds of kilometers using conductors suspended from guyed transmission towers. Towers located in central and northern Manitoba can heave or settle due to discontinuous permafrost. The problem is that excessive heave can cause loss of guy wires or buckling of tower shafts and excessive settlement allows lateral leaning of the towers. The tower of interest in this thesis is the latticed tower of Manitoba Hydro designated as A-203. The objective of this thesis project is to design a tower-support method that will safely permit an A-203 tower to heave or settle. A new method of tower support is proposed which allows the tower to heave four inches or settle six inches from its mean seasonal position. The method involves retrofitting existing towers with a device called the guy-wire tension stabilizer or GTS. The device consists of a large spring and locking mechanism which is installed between the guy wires and tower. As the tower base heaves or settles, the spring displaces to maintain acceptable guy-wire tension. When wind loads act against the tower and conductors, the spring is temporarily restrained by the locking ring, preventing excessive leaning of the tower. A 1:20 scale steel model of the device and tower was built for demonstration. The objectives, as stated by the client, have been met. A design of a tower-support method for the tower of interest has been prepared. It is recommended that consideration be given to developing the GTS to a working prototype.