Radio Shack 22-812 Owner's Manual - page 20
Ma
king M
easurem
ent
s
20
To set manual range control, press
RANGE
then change the range (if necessary) by
repeatedly pressing
RANGE
.
4. Touch the probes to the circuit you want to test.
/
'#574+0)
"
#%
"
8
1.6#)'
"
4
+&+0)
"
10
"
#
"
&%
"
5
174%'
"
$
+#5
To measure AC voltage superimposed on a DC
voltage source bias while ignoring the DC voltage,
follow the steps for measuring AC voltage under
“Measuring AC Voltage” on Page 19.
R
/
'#574+0)
"
6
*4''
/
2
*#5'
"
#%
"
8
1.6#)'
Your multimeter is designed primarily to measure
household AC voltages. If you want to measure 3-
phase, line-to-line voltage, please note the
following:
• Because of the dangers inherent in measuring
three-phase circuit, we strongly recommend
you do not use this meter for such applications.
• The actual voltage can be greater than the
circuit’s rated line-to-ground voltage.
Most 3-phase power circuits are rated by their line-
to-line voltage. This voltage is higher than the line
(or phase) to ground voltage. To determine if a line-
to-line 3-phase voltage exceeds the rating of this
meter, multiply the 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.
R
/
'#574+0)
"
&%
1
#%
"
%
744'06
To measure AC or DC current, you must break the
circuit and connect the test leads to two circuit
connection points. The connection must be in series
with the circuit under test.
Rý
.
.
.
.
1. Rotate the function selector to
/
µµµµ
A/A
ýýýý
for
0.4/4mA and 4/10A ranges or
/ mA/A
for 40/
400mA and 4/10A ranges.
ý
R
"
9#40+0)
ý
R
"
Measuring AC Voltage
Riding on a DC Source
Bias
To avoid injury or damage
to your meter, never try to
measure an AC voltage that
is riding on a DC source
bias where the peak AC
voltage exceeds 1000 V
with respect to earth ground.
Measuring Three-
Phase AC Voltage
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 dangerous shock
hazard to you, and could
also damage the meter.
Measuring DC/AC
Current
Do not apply voltage directly
across terminals. You must
connect the meter in series
with the circuit.
.
"
%#76+10
"
.
Measuring DC/AC
Current
•
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.
(continued)
22-812.fm Page 20 Monday, April 8, 2002 1:32 PM