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4.6 Continuity / Diode tests
Disconnect the UUT from all sources of supply and check that
it is at zero voltage
Only for UNITEST Clamp Meter CHB 37
:
the “ “ button can be used to switch between acoustic continuity
testing “ “ and diode testing “ “.
4.6.1 Continuity testing
4
Turn selector switch (3) to “ + “.
(for the UNITEST Clamp Meter CHB 7 to “ “)
4
Press the “ “ button one or more times, until the “ “
symbol appears in the LC-display.
4
Plug the black test lead into the “COM“ socket and the red lead
into the “+“ socket.
4
Connect the probes to the UUT.
A “beep“ sounds if the resistance is less than 40
V
.
4.6.2 Testing diodes
4
Turn selector switch (3) to “ + “.
(for the UNITEST Clamp Meter CHB 7 to “ “)
4
Press the “ “. button one or more times, until the “ “
symbol appears in the LC-display
4
Plug the black test lead into the “COM“ socket and the red lead
into the “+“ socket.
4
Connect the red probe to the anode of the diode and the black
probe to the cathode. If the diode is OK the forward voltage is
displayed.
4.7 True RMS measurements / Crest factor
(
only UNITEST Clamp Meter CHB 37
)
True RMS measurements
:
Commonly available clamp meters give an average value, and are
therefore only suitable for measuring DC, and pure sine-wave AC
currents and voltages. If the AC current or voltage is not a true
sine-wave, for example due to distortion from a phase controller,
then true RMS measurements must be made – with the
UNITEST
Clamp Meter CHB 37
, they can be.
PTDB93470-05.qxd 14.12.2005 9:56 Uhr Seite 26
