Section 4-vibration of conductors and overhead ground wires

Among the problems connected with the 220-kv. lines, that of the vibration of conductors and ground wires has claimed its share of attention. On account of the larger diameter of the conductors this phenomenon is clearly visible, and exaggerated reports are frequently received that the conductors are jumping up and down 6 in. or more. There have also been complaints of the rattling of towers, even on still nights. In one instance a conductor failed at the outer end of a dead end clamp and the appearance of the broken strands indicated that vibration might have caused the break. A second conductor was discovered with 28 aluminum strands out of a total of 54 broken at the end of a dead end clamp. Numerous rases of broken ground wires have been found, the strands breaking at the point of attachment to the towers. In a few cases ground wires have fallen but a larger number of broken strands has been discovered by inspection and repaired before complete failure of the cable. These troubles led to an investigation of the vibration problem as it appears in the spans of the Big Creek and Eagle Bell lines. While this investigation has not yet led to definite conclusions as to the cause of vibration and method of preventing it, the information obtained is presented here as a part of the operating record.