METODA DES 62 ?I METODA ?N TRIUNGHI PENTRUM?SURAREA REZISTEN?EI DE DISPERSIE A PRIZELOR DEP?M?NT

摘要

The DES 62% line measurment method is the most accurate method being used where groundrngeometry is complicated and because the measurment is made easily. It’s only limit is the fact that thernground is considered as a singular unit, therefore earth resistivity is homogeneous. The twornmeasurement electrodes ( current and voltage) are standing in the same line with the groundingrnelectrode which resistence is going to be measured. The current and voltage electrodes once fixed,rnusing two cables of enough length, the connection joining with the measurment device is made. Therngrounding electrode coonection with the device must be made through a 2 m maximum length cablernto reduce the measuremnt error otherwise the device will take into account cable resistance. Thisrnmethod advantage is the fact that it is quick and accurate, other measures for safety work beingrnuseless. Also it’s very important to know exactly geometrical dimensions and shape of the groundingrnelectrode. The triangle method is used when, because of obstacles, the alignment of two electrodesrnwith the grounding electrode is imposible to made.Thus, grounding electrode P and voltage andrncurrent electrodes must form, as much as possible, an equilateral triangle. A first measurment isrnmade by placing the voltage electrode S in A and after that, a seconde one, placing the same electrodernS in B, a point symmetrical to A. The obtained values are compared. If they are very different, the PArnelectrode is in the influence area of grounding electrode P, and the distance between them have to bernincreased, and the measurments will be repeated. Sometimes this method provide uncertain data. It’srnindicated that measurments shall be made cautiously especially regarding the distance betweenrncurrent electrode and grounding electrode and, also, electrodes must be in the same plane.rnIntroducing auxiliary electrodes on inclined plane will create wrong results.