25
noise) suppression. Choose 100 PLC to provide the best noise suppression, but the
slowest measurement speed:
For the
HDM3000
, by default
Aperture NPLC=10PLC
, use the Up/Down arrow
keys to specify the integration time in the Power Line Cyclings (PLC) for
measurement.
1, 10 and 100 PLCs provide normal mode (line frequency noise)
rejection.
Choose 100 PLC to provide the best noise rejection, but the slowest measurement
speed.
Step 4:
Select a Range for measurement by pressing
Range
. You can also use the [+], [-], and
[Range] keys on the front panel to select ranges.
Auto (adjusting the range
automatically) based on input.
Compared with manual range, automatic range
adjustment is more convenient, but can lead to slower measurement. Automatic range
adjustment can turn the range up to 120% of the current range and down to less than 10%
of the current range.
Step 5:
Auto Zero
: Auto Zero provides the most accurate measurement, but requires
additional time to perform the reset-to-zero measurement.
With Auto Zero enabled
(ON), the DMM makes an internal measurement of the offset after each measurement.
Then the offset value is subtracted from the previous reading.
This prevents the offset voltage on the DMM input circuit from affecting the measurement
accuracy. With Auto Zero disabled (OFF), the DMM makes a measurement of the offset
and subtracts the offset from all subsequent measured parameters. Each time you
change a function, range, or integration time, the DMM makes a new offset measurement.
(There is no Auto zero setting for 4-wire measurement.)
Step 6: Specify the input impedance (Input Z) of the test lead.
This will specify the
measuring terminal input impedance and can be auto or 10 M
Ω
. Auto mode chooses
high impedance (HighZ) and can be applicable to 100 mV, 1 V and 10 V ranges while 10
M
Ω
applies to 100 V and 1000 V ranges. In most cases, 10 M
Ω
is high enough to not
load most of the circuit, but also low enough, to stabilize the reading of the high
impedance circuit. It will cause the noise included in readings below HighZ option, this
option is suitable for 10M
Ω
a large load.
