Measuring Dc/Ac Current - Radio Shack 22-812 Owner's Manual

rated line-to-ground voltage by 1.732
(the square root of 3). For example, if
the rated line-to-ground voltage is
640 volts, the line-to-line voltage is
640 × 1.732 = 1108 V AC.
WARNING: This voltage exceeds the
meter's rating. Therefore, you should
not connect the meter to this circuit or
to any equipment connected to the
circuit. Doing so could present a dan-
gerous shock hazard to you, and
could also damage the meter.
MEASURING DC/AC
CURRENT
To measure AC or DC current, you
must break the circuit and connect
the test leads to two circuit connec-
tion points. The connection must be in
series with the circuit under test.
WARNING: Do not apply voltage di-
rectly across terminals. You must
connect the meter in series with the
circuit.
Cautions:
• Never connect the test leads
across a voltage source. Doing
so can damage the meter or the
circuit under test. The maximum
input limit for AC/DC current
measurement is 10A.
• If you do not know the amount of
current in the circuit you are
measuring, always connect the
red test lead to
+10A MAX
22
1. Rotate the function selector
/ µ µ µ µ A/A
to
ranges or
and 4/10A ranges.
2. Press
SELECT
meter to measure AC current
(∼ ∼ ∼ ∼ appears). Otherwise, repeat-
edly press
meter to measure DC current
(∼ ∼ ∼ ∼ disappears).
3. Remove the power from the cir-
cuit under test and discharge all
capacitors.
4. Plug the black test lead into
and the red test lead into
COM
the appropriate jack.
5. Connect the meter's test leads in
series with the circuit.
6. Apply power and read the current
value. If the measurement is less
than 400mA and the red test lead
is connected
remove power from the circuit.
7. M o v e t h e r e d t e s t l e a d t o
+ V.mA.Ω Ω Ω Ω
8. Rotate the function selector
/ µ µ µ µ A/A
to
ing on the value you measured in
Step 6.
9. Reapply power to the circuit.
If you are measuring DC current and
the current's polarity is negative, –
appears before the value.
.
Making Measurements
ý ý ý ý for 0.4/4mA and 4/10A
for 40/400mA
/ mA/A
once to set the
to set the
SELECT
–
to ,
+10A MAX
.
or
ý ý ý ý depend-
/ mA/A