Basic Test Procedure - Megger DET5/4R Guia Del Usuario

BASIC TEST PROCEDURE

Four Terminal Measurement
After the test spikes have been set up and connected
to the instrument for the type of test to be carried out
(refer to 'Measuring Techniques') proceed as
follows:-
1) Press and hold the 4 pole push button. After a
short pause, this will begin the test sequence and
include spike resistance and 'Noise' verification.
2) Check that the display shows no adverse test
conditions, i.e. the 'Rp'; 'Rc' and 'Noise' LED's
with their alert warning indicator are not showing.
Also check that the low battery voltage warning is
not flashing.
3) After a few seconds the display will stabilise. If the
conditions for a test are satisfactory the reading
given on the display may be accepted as the earth
resistance. If any of the condition warning
indicators illuminate, the cause of the adverse
condition must be removed before the reading can
be accepted. The instrument autoranges on both
the earth resistance and Current loop resistance. If
the Current spike resistance is too high for the
required measurement range, the instrument will
autorange up to a lower current range which can
tolerate a higher Current spike resistance. This
results in a loss of resolution.
4) The push-button may be released at any time after
the instrument has commenced its test sequence.
Once the button has been released, the test will
continue for approximately 30 seconds.
To switch the instrument 'Off' before the test period
has elapsed, press and immediately release
either of the two push buttons. If the button is held,
the instrument will reset itself, and begin another
test sequence starting at point 1.
Three Terminal Measurement
The basic test procedure is the same as for the four
terminal measurement except that the 3 pole push
button is used to operate the instrument. Only one
connection is then required from the 'C1' terminal to the
electrode under test. For greatest accuracy this
connection should be made with a short, low resistance
lead since this lead resistance is included in the
measured value.
13