Measuring and testing – Dynamometers – Responsive to force
Patent
1988-11-08
1990-07-10
Ruehl, Charles A.
Measuring and testing
Dynamometers
Responsive to force
7386267, G01L 510
Patent
active
049399390
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an apparatus for measuring a traction force during the laying of cable, using a traction dynamometer disposed between the cable and a wire rope, the dynamometer including a force measuring sensor, e.g., strain gauges, and a measuring circuit which amplifies the signals received from the force measuring sensor and converts them into frequency-modulated signals proportional to the traction force, which are conducted to a meter receiver usually set up in the area of a pulling winch, a first conductor to the meter receiver incorporating the pull rope and another conductor incorporating the ground.
Apparatus are known (the French "FERTEX" apparatus, "Capteur de Traction") for measuring a traction force by means of a traction dynamometer, in which a traction dynamometer is inserted between the cable pull rope and the actual cable. The traction dynamometer converts the measured traction forces to a frequency-modulated signal which is transferred through the metal pull rope itself. A second conductor is the earth, and so-called earthing or grounding rods are driven in the area of the winch and at the other end so-called drag conductors are galvanically connected to the measuring thimble.
The known apparatus is disadvantageous because it requires that the winch equipment be galvanically separated from the ground and that the meter station be insulated, and because it is very sensitive to short-circuits in the measuring set-up. Furthermore it is a disadvantage that grounding rods always require a freely accessible area of ground. When the earth is plastered and asphalted or otherwise covered, it can be reached only with great difficulty. Since cable laying generally involves temporary worksites, the driving of the grounding rods and the repair of the damage it causes often consumes a great amount of time. It is furthermore disadvantageous that the attached drag conductor is easily pinched off by the pulling, parallel cable, especially in curves.
The problem accordingly arises of improving an apparatus of the kind described above so as to reduce the time needed for the construction and removal of the measuring and pulling stations on the one hand and on the other hand to make them less liable to trouble during pulling and measuring.
This problem is solved in an apparatus for measuring traction force by the fact that the output of the measuring circuit, which is connected to the conductor carried over the ground, has an appropriate measurement signal carrier frequency that is preferably between 3 and 100 kHz, and transmits the signals through the ground to the measurement receiver with a capacitive coupling separated galvanically from the ground.
In the apparatus described above, the dynamometer, the transmission lines and the measurement receiver are coordinated with one another such that a distance of 3000 meters can be covered. At the same time the traction dynamometer and the measurement receiver can be associated basically with any desired pulling winch. The advantage of the above-named capacitive coupling and uncoupling of the measurement signal through an earth connection is that no galvanic grounding rods and drag conductors are necessary.
A further advantage of the apparatus is that use can be made advantageously of the circumstances involved in the cable laying.
If the laying operation involves, as it commonly does, cables which contain at least one insulated metallic conductor or shielding, the cable end can be surrounded on part of its length by an electrically conductive sleeve or mesh-like device, which is connected electrically to the measuring circuit and forms a first condenser. The metal conductor of the cable forms on the rest of the length of the cable a condenser electrode with respect to the ground. A conventional metal cable grip can be used as the sleeve-like or mesh-like device.
At the measurement receiver end, an insulated plate electrode which can be laid on the ground is preferably connected to the input of the receiver. This is preferably a kind of rubber mat, i.e.
REFERENCES:
patent: 3823395 (1974-07-01), Rigney et al.
patent: 4458880 (1984-07-01), Conti
Peter Lancier Maschinenbau-Hafenhuette GmbH & Co.,KG
Ruehl Charles A.
LandOfFree
Apparatus for measuring a traction force by means of a traction does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for measuring a traction force by means of a traction , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for measuring a traction force by means of a traction will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1715012