Conductor galloping, also known as conductor dancing, is a hazardous phenomenon related to the fact that wind induces the self-excited vibrations of overhead electric power line conductors. A test setup for inducing various kinds of vibrations, which is also used for galloping tests, has been established at the GIG Laboratory of Electric Power Grid Systems.
Vibrations induced by conductor galloping are the most hazardous type of vibrations occurring in overhead electric power lines. They may bring the conductors closer to one another or result in damage to the conductors, insulators and towers, which is why it is necessary to have the possibility of simulating this phenomenon under laboratory conditions and assessing its influence on the durability of conductors and other elements of overhead power lines. The vibrations may have a particularly unfavourable influence on ground wires with optical fibres, i.e. OPGW.
Currently, conductor galloping testing is not performed by any laboratory in Europe. Such tests are carried out only by Chinese laboratories and the Kinectrics lab in Canada.
Standards and technical specifications of various transmission system operators obligate the conductor manufacturers to test the conductors and other equipment for resistance to the galloping phenomenon, explains Mariusz Szot, D.Sc. Eng., the Head of the Laboratory. The most common requirement is to test a conductor section of at least 35 m in length at the appropriate tension, vibration frequency and amplitude. It should be noted that conductor dancing is a vibration at very low frequencies, ranging from 0.1 to 1 Hz, which necessitates the performance of at least 100 thousand cycles and makes this test very time-consuming.
The assessment criteria include the lowest possible change in optical fibre attenuation, no conductor element damage, and no damage to the equipment working in conjunction with the conductor.
The Laboratory of Electric Power Grid Systems is a new lab that was established at GIG in response to the increased demands of domestic and foreign manufacturers concerning the testing of equipment used in electric power lines. In September 2021, the Laboratory of Electric Power Grid Systems achieved a positive evaluation following an audit carried out by the Polish Centre for Accreditation within the standard scope pertaining to OPGW testing. The accreditation will undergo successive expansion as the comparative tests required for this process are carried out. Our goal is to be able to conduct all the mechanical and optical tests within the next few months, says Andrzej Pawłowski of the GIG Laboratory of Electric Power Grid Systems. As concerns short-circuit and atmospheric discharge testing, we will cooperate with national research institutions specialised within this scope to allow our clients to receive reports encompassing the full range of tests required by the relevant standards.
