Stakeless" Earth Electrode Testing - Megger DET3 Series Sales Manual

"STAKELESS" Earth Electrode Testing

Earth electrode testing can be a difficult and time-consuming business; this is why
Megger is committed to making life as easy as possible for you. Our experience of
real life situations led to the introduction of ART, first seen with the DET3TC, and
now with the DET4TC we add the capability to perform Stakeless measurements.
Adding a second clamp, the VCLAMP, the DET4TC can be used to measure
electrode resistance in locations where driving stakes is not practical.
To take a measurement simply select the dual clamp range on the DET4TC, connect
the ICLAMP and the VCLAMP to the appropriate terminals. Then clamp both of them
around the electrode under test (or the cable connected to the electrode) and press
the test button, simple. However there are a few simple things to remember.
The first is that there must be at least 100mm gap between the clamps. This is to
ensure the field around the clamps do not interfere with each other. The result would
be incorrect readings.
Lets take a look at the test in practice:
Building earth
connection/s
Current is induced into the circuit by the ICLAMP and then the resulting voltage is
measured with the VCLAMP. From this the resistance of the compete loop / current
path can be measured.
The important thing to remember is that the method measures the resistance of the
total loop, where the test current in flowing. Therefore it is important to understand
the path the test current is taking.
Megger Limited
DET4TC/R Launch
ICLAMP
VCLAMP
Ground
Electrode
Under
Test
PWS / Nov 06
23