Thursday, August 2, 2012

Earth / Ground Test (version 2)

This Method of Statement is meant to describe in generality the Earth Grid Test process; which describes its general setup and how the test is carried out.
2.      SAFETY
All personnel should continuously and consciously observe his work area for any potentials danger and take adequate measures.

In general:
a)      All personnel should wear Personal Protective Equipments suitable for the work and work area (e.g helmet, safety boots, goggles, glove, etc)
b)      If working in live station, ensure that isolation is done and Permit To Work is issued. If possible, ensure no REMOTE operation is allowable such as put the section into LOCAL.
c)      Ensure that the working area is only at the permitted area.
d)     Earth/ground test equipment

a.         General Setup

For this Method of Statement, we use KYORITSU Digital Earth Resistance Tester as our test equipment.

Setup the equipment as shown in Figure 1;

-            Stick the auxiliary spikes P and C into the ground deeply. They should be aligned at an interval of 5-10mtr from the earthed equipment under test. Connect the green wire to the earthed equipment under test, the yellow wire to auxiliary earth spike P and the red wire to the auxiliary earth spike C from terminals E, P and C of the instrument in order.
-            Set the range switch to the EARTH VOLTAGE position in the condition of

1.    Earth voltage will be indicated on the display. Make sure that the voltage is 10V or less. When the display reads more than 10V, it may result in excessive errors in the earth resistance measurement. To avoid this, make measurement after reducing the voltage by turning of the power supply of the equipment under test etc.

b.                 Test Process

Set the range switch to 20Ω position and press the push button (PRESS TO START). LED remaining laminated during the testing. Let the device for a few second and the measured value will appear on the LCD Display.

If the auxiliary earth resistance of auxiliary earth spike C is too high to make measurement, the display reads ‘….’ Recheck the connection of the test leads and the earth resistance of auxiliary spikes.

c.                  Test Acceptance Value

-      Resistance value for earth rod - less than 10Ω

-      Resistance value for earth rod with cooper tape  - less than 1Ω

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