User Guide

Measurement Operation(10)

Model UT90C: OPERATING MANUAL

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 theµAmA 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 orA .

4. The Meter defaults to DC current measurement mode.

To toggle between DC and AC current measurement

function, press SELECT button. AC current is

displayed as an mean value (calibrated against sine

wave effective 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.

Note

l For safety sake, the measuring time for high current

should be less than 10 seconds for each measurement

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 testing leads

and the circuit under test, and remove the testing

leads away from the input terminals of the Meter.