2/2012 - Fingrid

1.Stages of testing oftransmission line towerBefore testing, the designer of thetower and the testing station drawup a test programme. The test programmecontains information on theloads that the tower is designed towithstand, and the proposed testingsequence and testing method, includingthe fixing points of pull wires.Manufacture of the tower, transport tothe testing station, and erection.2. 3.The load sensors are calibrated to ensurethe accuracy of the results.Pull wires and load sensors, whichmeasure the load exerted on the towerby the wires, are attached to thetower.If the testing also covers the measurementof stresses occurring in thesteel, strain gauges are attached tothe towers.4.The guys of the tower are providedwith measuring instruments used formonitoring the forces created in theguys.The load situations are examined inaccordance with the test programme.Displacements are measured at eachload step (50%, 75%, 90%, 95%, 100%)and also when the load has comedown to zero (permanent deflection).Material samples are taken from thetower, used for ensuring that the steelin the tested tower is of the right quality.After the tests, the tower is scrappedand recycled. The towers are testedwith no zinc coating, because galvanizingis expensive, and it does notchange the strength properties of thesteel.1. The tests model a variety of forces exerted on the towers. The forcesare directed to the tower structures via portals by means of pull wires.2. The loads are created by means of automatically-controlled winches.3. The load sensors of the test equipment are provided with a directoptical fibre connection to the computer in the control room of the testingstation.4. Before testing, the pull wires are secured to the tower structuresand tightened. The tapes on the tower are used for fastening the straingauges, which measure the tensions occurring in the steel.FINGRID 2/2012 | 12