Sinusoidal Polarity (the 0° or 180° test)
RCD’s often operate with dierent reaction times depending upon whether the fault is
introduced during the positive or negative half cycle of the AC waveform. Therefore to
accurately determine the maximum response time of an RCD it is necessary to test it
twice at each given fault current, firstly with the fault introduced during the positive half
cycle and secondly during the negative half cycle.
The Socket & See MFT5000 takes care of this for you by alternating the start point of
consecutive tests at any given setting. If for example you have selected a test at the
rated trip current (x1) of a 100mA RCD, the first press of the test button will apply a
100mA fault current starting on the positive half cycle (0°) and display the result. A
further press of the test button will carry out another test at the same current but
starting on the negative half cycle (180° ).
Test Leads
Where testing is to be conducted at a point on the circuit other than a socket outlet the
distribution board test lead set Socket & See SOC/DLMPROLEAD is used in 3-wire
mode as described in the previous chapter. The probes can be fitted with either prod
tips or crocodile clips as required.
Mains Supply Wiring and Voltage Test
When first connected to a mains supply the Socket & See MFT5000 will automatically
conduct a safety test to ensure that the Live, Neutral/Earth conductors are correctly
connected and that the supply voltage is in the acceptable range of 207-253V.
If all is well the VOLTAGE/POLARITY warning LED will light Green and the supply
voltage will be displayed in the primary display area.
In the event of a problem with either the mains voltage supply or reversed connections
the VOLTAGE/POLARITY warning LED will light Red, a warning tone will be sounded
and testing will be inhibited.
RCD Test Procedure
Select the type and rating of the RCD to be tested with the rotary function selector
switch and RCD AC/A button.
Connect the 4mm plugs of the chosen test lead to the corresponding L, N & E terminals
of the Socket & See MFT5000 and connect the other end to the socket or circuit
terminals under test.
If using the distribution board test lead set Socket & See SOC/DLMPROLEAD observe
the correct polarity by connecting the Brown probe to the Live conductor, Blue to
Neutral and Green to Earth.
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