どのように に 使用 a マルチメータに に テスト 接地 抵抗
Normally, when testing ground resistance, it is necessary to bury the ground body and lead out the ground level so that the instrument and equipment can be reliably grounded. In order to ensure that the ground resistance meets the requirements, a special ground resistance tester such as Japan Kyoritsu 4105A ground resistance tester/Kyoritsu 4102A is usually required for measurement. Or use a relatively expensive clamp-type ground resistance tester.
しかし, in use, a special ground resistance tester is expensive and inconvenient to purchase. Can a multimeter be used to measure ground resistance? The author used a multimeter to conduct experiments on ground resistance in soil of different soil types, and combined the data measured by the multimeter with the special ground resistance tester. The data measured by the resistance tester were compared and the two were very close. The 特定 測定 方法 are as follows:
Find two 8mm, 1m long round steels, sharpen one end as an auxiliary test rod, and insert them into the ground 5m away from both sides of the grounding body A to be tested. The depth should be more than 0.6m, and keep the three in a straight line.
ここで, A is the grounding body to be tested, B and C are auxiliary test rods
Then use a multimeter (R*1 gear) to measure the resistance values between A and B; A and C, recorded as RAB, RAC, and RBC respectively. Then through calculation, the grounding resistance value of grounding body A can be found.
because ground resistance refers to the the contact resistance between the ground body and the soil. Let the grounding resistances of A, B, and C be RA, RB, and RC それぞれ. 仮定 the resistance of the soil between A and B is RX. Because the distance between AC and AB is equal, the soil resistance between A and C can also be RX; and because BC=2AB, the soil resistance between B and C is approximately 2RX, then:
RAB=RA+RB+RX. . . . . .
①RAC=RA+RC+RX. . . . . .
②RBC=RB+RC+2RX. . . . . .
③ Put ①+②-③ to get: RA=(RAB+RAC-RBC)/2. . . . . . . ④
式 ④ は 計算 式 地表 抵抗。
Actual measurement example: The measured data of a certain grounding body today are as follows: RAB=8.4∩, RAC=9.3∩, RBC=10.5∩. but:
RA=(8.4+9.3-10.5)/2=3.6(∩)
したがって、, the ground resistance value of the measured ground body A is 3.6∩です。
It is worth noting that before measurement, the three grounding bodies A, B, and C need to be polished and shiny with sandpaper to minimize the contact resistance between the test leads and the grounding body to reduce errors.
