Megger LCB2000/2 Guide De L'utilisateur page 23

Operation - RCD Testing
Display Type of Test
1 ⁄ I
No Trip
2
0° Trip Test
180° Trip Test
Ramp Test
5I
Trip Test
Pressing the I key displays the Type of Test symbols individually
in sequence. Select the type of the test to be performed.
22
Description
Performs a no-trip test at half the
rated current of the selected
RCD.
The test measures the earth loop
resistance and contact voltage.
Trip test at the rated current of
the selected RCD. A 1 ⁄ I test is
2
carried out before this, and the
resistance and voltage are
available after the test. The test
is always started on a zero
crossing when the instantaneous
voltage is on the rise.
As above, but the test is always
started on a zero crossing when
the voltage is on the fall.
Test current increases from half
the rated current of the RCD. The
result is the current at which the
trip opens.
Trip test at 5 x the rated current
of the selected RCD. The choice
of 0° or 180° gives greater
accuracy of measurement. A
test is carried out before this,
and the resistance and voltage
are available after the test.
No Trip RCD Tests
When an (or No Trip) test is performed, the loop or
1 ⁄
I
2
earth resistance is measured, and in Setting b, a two
second No Trip test follows.
Loop resistance approximation - (During RCD Test)
During the RCD test and approximation of the circuit
loop impedance is possible. In this case the loop
resistance is measured at half the rated RCD current
selected. Contact voltage is also displayed which is the
loop resistance multiplied by the rated RCD current. A
high loop resistance will cause the instrument to display
>90V, and safely abort the test.
2 second No Trip test (Setting B only)
This tests that the RCD does not trip when half the
rated operating current of the RCD is drawn for 2
seconds. Tripping of the RCD will indicate that it is over
sensitive, or that excessive earth leakage current is
being drawn in the system. The load put onto the circuit
is resistive and therefore the test current is sinusoidal if
the supply is sinusoidal.
No Trip testing
The test is the same for all RCD types. Select the Rated
1 ⁄ I
2
Current, the RCD Type and
installation and press the TEST key. If the settings are
correct, and the RCD is in order, the RCD trip should
not operate and the contact voltage will be displayed. If
the RCD trip does operate during the test, the message
no is displayed. This could be due to incorrect current
rating selection, excessive leakage current in the circuit,
. Connect to the
1 ⁄
I
2