Fluke 189 [52/96] Measuring current

Model 187 & 189

Users Manual

3-16

Measuring Current

WWarning

Never attempt an in-circuit current

measurement where the open-circuit potential

to earth is greater than 1000 V. You may

damage the meter or be injured if the fuse

blows during such a measurement.

Caution

To avoid possible damage to the meter or to

the equipment under test, check the meter’s

fuses before measuring current. Use the

proper terminals, function, and range for your

measurement. Never place the probes across

(in parallel with) any circuit or component

when the leads are plugged into the current

terminals.

Current is the flow of electrons through a conductor. To

measure current, you must open the circuit under test,

then place the meter in series with the circuit.

To measure ac or dc current, proceed as follows:

1. Turn off power to the circuit. Discharge all high-

voltage capacitors.

2. Insert the black lead into the COM terminal. Insert the

red lead in an input appropriate for the measurement

range as shown in Table 3-1.

Note

To avoid blowing the meter’s 440 mA fuse, use

the mA/

A terminal only if you are sure the

current is less than 400 mA.

Table 3-1. Current Measurement

Rotary Switch Input Ranges

I or K!

5.0000 A

10.000 A (reading flashes at

10 A, overloads (0L) at 20 A)

50.000 mA

500.00 mA

= or x

500.00 µA

5000.0 µA