Implements or apparatus for applying pushing or pulling force – Method or apparatus for placement of conductive wire – Utility pole guide
Patent
1990-06-11
1993-06-22
Watson, Robert C.
Implements or apparatus for applying pushing or pulling force
Method or apparatus for placement of conductive wire
Utility pole guide
B65H 5900
Patent
active
052210740
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a suspension device that allows to support and string conductors on low, medium, high, and extra high transmission lines.
BACKGROUND OF THE INVENTION
It is well known to the experts in the art of power lines construction that the stringing and clamping-in procedures usually comprise the following operations:
position one pulley per each crossarm of each tower and suspend each of said pulleys from the strings of insulators hanging from each crossarm,
lay on the ground one service cable per each phase of the power line according to the layout of the towers,
lift and position each service cable on each respective pulley,
tension each of said service cables from one end by means of a winch and from the other end by means of a brake,
pull the service cables by means of said winch, and replace each service cable with a conductor and/or a larger draw cable if a bundle of conductors has to be positioned per each phase of the line,
position all conductors and/or bundles of conductors on their respective pulleys, while keeping said conductors and/or bundles of conductors always under tension and therefore always raised from the ground,
pull the conductors and/or bundles of conductors by means of said winch till they reach the prescribed degree of tension (pre-sagging) (if longitudinal unbalances are present the pre-sagging of the conductors at this stage cannot be the equal to the final and correct sagging),
if longitudinal unbalances are present, due to the fact that the power line is crossing mountains and/or the distance between towers is not constant, calculate said longitudinal unbalances, and mark the plumb-point on each conductor so that once the conductors have been clamped-in to said insulators, the insulators will be plumbed and the conductors sagged,
temporarily lift, by means of one or more tackles, the conductor and/or each conductor of a bundle from the grooves of a pulley, remove said pulley, clamp-in the conductor and/or conductors to the insulators, and once all conductors have been clamped-in to the insulators of all towers between the brake and the winch, control, and often adjust, the sagging of said conductors.
It is to be understood that when longitudinal unbalances are present, before the crews can proceed with the last described operation, that is to say before they can clamp-in the conductors, said tackles have to be used not only to lift the conductors from the pulleys, but also to pull said conductors, with repeated operations, in order to recover the calculated differences between the "rest" position of the conductors on the pulley and the final clamp-in points. This additional operation has to be carried out with absolute accuracy so that once said conductors have been clamped-in to the insulators of all towers between the brake and the winch, said insulators will remain perfectly plumbed, and only vertical loads will be imposed to the crossarms of suspension towers.
There are many difficulties related to the stringing of power lines and while some of them, particularly these relating to the positioning of the service cables on the towers, have been faced and solved for example as described in the U.S. Pat. No. 4,596,379 (Europe N.56285) of the same assignee, patent that can be referred to for a better understanding of state of the art of the different stringing methodologies, the others, and particularly those relating to the clamping-in and plumbing operations, have been faced, but not solved.
The difficulties relating to the clamping-in of the conductors to the insulators, as partially explained, are the following:
1. stringing conductors on angle towers, that is to say on towers which cause the conductors to run on different vertical planes, causes the pulleys to be displaced to a non-vertical position. The displacement of the pulleys, in its turn, causes the conductors to cross the grooves of the pulley. In fact, while the two catenaries adjacent to the tower are points. This additional operation has to be carried out with absolute
REFERENCES:
patent: 4844419 (1989-07-01), Danielsson
Tesaut S.p.A.
Watson Robert C.
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