Calix 560 SBU ONT, Руководство по установке

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As the layers extend outward from the electrode, their surface area becomes larger compared
to the layers nearest the electrode. The resistance of each of layer decreases in relation to the
amount of surface area. From a starting point next to the earth electrode, the resistance
measurement to earth will increase with distance. The amount of resistance increase due to
distance will taper off at some point. As the distance from the electrode increases, the
resistance to earth does not increase. As more measurements are taken beyond this point, the
amount of resistance to earth will start to increase again.
AC Voltage
Source
Volt/Ohm
Meter
Test Rod “P”
Test Rod “C”
Earth
5225
The test setup uses an Earth Resistance Megger to determine the resistance of an earth
electrode. Grounding system tests are commonly made with a “full of potential” test set.
Within the test set is a AC current source, a voltage meter and a number of test terminal
binding posts. The AC voltmeter inside of the test set reads out directly in Ohms of
resistance. By reading the voltage drop across a current path and applying Ohms Law, the
total resistance of the ground plus the surface resistance of the earth electrode to the
surrounding ground can be measured.
Full-of-Potential Testing Method
The “Full-of-Potential Method” sometimes referred to as the “Three Terminal Method”, is
the most commonly accepted way to measure the total resistance of a grounded earth
electrode. Providing that the measured resistance at the conclusion of the test meets the
specified requirements, then no additional testing should be required. The test procedure
measures the total resistance of the earth ground electrode, the contact resistance of the
electrode to the earth and the earth near the grounding system.
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