Measurement Operation (10)
auto ranging.
The current measurement has 3 measurement positions on the
rotary switch: A
, mA
and A
.
The A
has a 400.0 A and 4000 A range, with auto ranging;
the mA has a 40.00mA and 400.0mA range, with auto
ranging; A position has a 4.000A and 10.00A range, with
To measure current, do the following:
1. Turn off power to the circuit. Discharge all high-voltage
capacitors.
2. Insert the red test lead into the
or 10A terminal
and the black test lead into the COM terminal.
Use the 10A terminal and A range if the current value to
be tested is an unknown.
3. Set the rotary switch to µA
, mA
, or A
.
4. The Meter defaults to DC current measurement mode. To
toggle between DC and AC current measurement function,
press BLUE button.
Model 72-7740: AC current is displayed as effective
value of sine wave (mean value response).
Model 72-7745 : AC current is displayed as true rms value.
5. Break the current path to be tested. Connect the red test lead
to the more positive side of the break and the black test lead
to the more negative side of the break.
6. Turn on power to the circuit.
The measured value shows on the display.
l
For safety sake, each measurement time for high current
should be less than 10 seconds and the interval time between
2 measurements should be greater than 15 minutes.
l
When current measurement has been completed, disconnect
the connection between the test leads and the circuit under
test, and remove the test leads from the input terminals
of the Meter.
Note
l
(TRMS) stability period: (Model 72-7745)
When the reading obtained is less than 100 digits, the true
root mean square value converter needs a longer time to
stabilize. When there is no input voltage, the maximum reading
displayed is 10 digits.
23
Model 72-7740/72-7745: OPERATING MANUAL
o
C
