Electricity: measuring and testing – For insulation fault of noncircuit elements – Where a moving sensing electrode scans a stationary element...
Patent
1989-04-06
1991-01-01
Strecker, Gerard R.
Electricity: measuring and testing
For insulation fault of noncircuit elements
Where a moving sensing electrode scans a stationary element...
324557, 324240, G01Y 311, G01R 3108
Patent
active
049821636
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method and a device for the determination of the condition of the insulation of an object made of an electrically conducting material, coated with an electric insulation and positioned in an electrically conducting medium. More specifically, it is possible by means of the method and the device according to the invention to monitor the condition of the electric insulation of electrically conducting objects, such as pipes and cables, within an electrically conducting medium such as sea water, and to locate the possible damages in the insulation.
Pipe systems and cables are frequently mounted in the ground, in water and on the bottom under the water, and these are insulated from the surroundings e.g. due to the electric currents flowing therein or for the prevention of corrosion. Very many of the insulations are also electric insulations, although this would not be the primary function of the insulation. The insulations may have been damaged already during the manufacture of the objects or they may be damaged later for various reasons. The condition of the insulations has to be checked often enough so that any damages occurring in the insulations could be repaired before the damage reaches the object to be protected. Moreover, the location of the damage has to be determined in order to be able to repair the insulation.
The condition of insulations of structures positioned in water can be monitored by means of methods based on the propagation of light waves, e.g. by visual appreciation made by a diver or by appreciating photographs. Such methods, however, are very slow, and it is difficult to find all damages by means thereof. Furthermore, the use of the method is extremely difficult if not impossible deep under the water or when checking underground objects.
The condition of an insulation can also be monitored by applying a direct or an alternating current to the object to be monitored, whereafter e.g. the potential field is measured around the object. According to U.S. Pat. No. 3,526,831, a power source is attached to the object to be examined, whereby measurements can be made in water only. According to European patent application No. 77,757, the measurement is carried out by means of a measuring sensor positioned between a feed electrode and the object to be examined.
In the method according to U.S. Pat. No. 4,365,191, leakage points can be located by measuring the potential difference between the object to be examined and an electrolyte such as sea water. The condition of the insulation of objects provided with sacrificing anodes as well as the operation of the anodes can be monitored e.g. as described in U.S. Pat. No. 4,228,399, whereby the contact to the object has to be maintained all the time, or without any contact as in U.S. Pat. No. 4,078,510.
Prior methods for monitoring the condition of insulations have many disadvantages. In certain methods an electric current has to be applied to the object to be monitored. In case of an object insulated on all sides this cannot be effected without damaging the insulation. Some methods are operative only with a cathodically protected object.
The object of the invention is to eliminate the disadvantages of the prior art and provide a versatile method and a device by means of which the condition of electrically conducting objects coated with an electric insulation and positioned within an electrically conducting medium can be monitored completely independently irrespective of the way of protection of the object. No physical contact with the object to be monitored is required, and the measurement can, within a usable measuring distance, be carried out even from outside the conducting medium.
The above objects of the invention can be achieved by means of a method according to the invention which is characterized in that a first electromagnetic field is created in the conducting medium, which field induces eddy currents both in the medium and in the conducting object positioned therein, a second electromagnetic field created by the eddy c
REFERENCES:
patent: 3745452 (1973-07-01), Osburn
patent: 4091322 (1978-05-01), Stankoff
patent: 4134061 (1979-01-01), Gudgel
patent: 4348639 (1982-09-01), Karbowski
patent: 4390836 (1983-06-01), Bruce
patent: 4438389 (1984-03-01), DeSa
patent: 4602212 (1986-07-01), Hiroshima
patent: 4677379 (1987-06-01), Arnaud
patent: 4799010 (1989-01-01), Muller
Hamalainen Mikko
Viikari Matti
Aerius Oy
Solis Jose M.
Strecker Gerard R.
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