26
3.8 Measuring True RMS AC+DC
Model TH1942 can measure the True RMS value of AC+DC voltages and currents.
When
is pressed, the multimeter will measure the dc and ac signals respectively then calculate
and display the AC+DC RMS value by using the following formula:
2
2
)
(
ac
dc
RMS
DC
AC
3.8.1 Connections
Assuming Model TH1942 is under factory default conditions, the basic procedure is as follows:
1. Connect test leads to
and COM terminals, as shown in Figure 3-7.
2. Press
DCV
,
ACV
,
Shift
→
DCV
or
Shift
→
ACV
to select a voltage or current measurement
3. Press
for true RMS measurement function.
4. Press
+
to turn on a 2
nd
display.
5. Press
or
to select a 2
nd
parameter available
6. Take a reading from the display.
DC
AC
SOURCE
VOLTAGE
MED
AUTO
！
CAT
Ⅰ
(
1000V
)
CAT
Ⅱ(
300V
)
Ω
COM
20A
T1AL 250V
ALL INPUT
1KV MAX
500mA
MAX
V
1000V
MAX
DC I
AC I
Period
dB
dBm
%
Comp
Hold
Menu
Local
2nd
DC V
AC V
Ω
Freq
AC+DC
Rel
Rate
Esc
Shift
Trig
Auto
mA
POWER
ON
OFF
TH1942
50000 Count Multimeter
DC+AC RMS volt measurement
V
1000V
MAX
DC I
AC I
Period
dB
dBm
%
Comp
Hold
Menu
Local
2nd
DC V
AC V
Ω
Freq
AC+DC
Rel
Rate
Esc
Shift
Trig
Auto
mA
POWER
ON
OFF
SOURCE
CURRENT
MED
AUTO
DC
AC
！
CAT
Ⅰ
(
1000V
)
CAT
Ⅱ(
300V
)
Ω
COM
20A
T1AL 250V
ALL INPUT
1KV MAX
500mA
MAX
TH1942
50000 Count Multimeter
DC+AC RMS current measurement
Figure 3-7 True RMS value of AC+DC voltages and currents Measurement
