Sonel CMM-40, User Manual

Page: 57 / 112

CMM-40
– USER MANUAL
55
5.5 AC current (frequency, duty cycle) measurements
ATTENTION!
Do not make 20A current measurements for longer than 30
seconds. Exceeding 30 seconds may cause damage to the
meter and/or the test leads.
In order to realise a measurement of AC current, it is necessary
to realise the following actions:

Insert the black test lead banana plug into the negative COM
jack,

For current measurements up to 4000
µA AC, set the function
switch to the
µA
position and insert the red test lead banana
plug into the
µA/mA
jack,

For current measurements up to 400mA AC, set the function
switch to the
mA position and insert the red test lead banana
plug into the
µA/mA
jack,

For current measurements up to 20A AC, set the function
switch to the
10A/HZ/% position and insert the red test lead
banana plug into the 10A jack,

Press the MODE
button to indicate “
AC
” on the display,

Remove power from the circuit under test, then open up the
circuit at the point where you wish to measure current,

Touch the black test probe tip to the neutral side of the circuit.
Touch the red test probe tip to the
“hot” side of the circuit,

Apply power to the circuit,

Read the current in the display. In the 10AAC range, right aux-
iliary display frequency,

Press and hold the MODE
button to indicate “
Hz
”,

Read the frequency in the display,

Momentarily press the MODE
button again to indicate “
%
”,

Read the % duty cycle in the display,

Press and hold the MODE button to return to current meas-
urement,

Press EXIT for 2 seconds into the function of AC+DC. Test DC
and AC True RMS,