HEME GEO 30 - Tequipment.net

Principle of Operation7 Principle of OperationThe following diagram (fig. 1) shows a simplified typical grounded distribution system.Its equivalent circuit (fig. 2) is shown below. If R 1 , R 2 , R 3 , ... R n is combined as R eq ,then only R g and R eq are left in the circuit (see figure). If a constant voltage is appliedto the circuit, the following equation is valid:UI=R g+ R eqwhere1Req = , i = 1,2,...n1∑RIf R g and R 1 , R 2 , ... R n are about the same, and n is a large number (such as 200),then R eq will be much less than R g and maybe approach zero.iRg>>eq( R → 0)Example:If R g and R 1 , R 2 , ... R n are all 10 Ω, respectively and n = 200, then R eq by calculationequalsReq= 1= 0, Ω1 1 105+ + ... +10 10 10UI= R + R = 10 + 0,05 = 10, 05 →geqRgIn this example, we can see that as long as the number of multiple electrodes is largeenough, the equivalent resistance is negligible with respect to the ground resistance tobe measured.HEME GEO 30 17SO8130Z Rev. B