NF DP420LS Instruction Manual page 244

Table 9-3 Actions When a Failure is Suspected (Continued)
Category
Output-related The measured
problem voltage is
different from
the setting
value.
An error
message is
displayed.
Measurement The measured
function-related voltage or
problem current is not
displayed
correctly.
The measured
value is
displayed as
"----".
The measured
value
fluctuates.
DP420LS/DP480LS
Symptom Possible Cause
The waveform is
set to CLP
(clipped sine
wave) and the
Type is set to
Clip (specified
clip ratio mode).
The protection
function was
activated due to
overload.
Excessive signal
level of the
signal generator.
The ambient
temperature is
high.
Air filters are
clogged.
Around the front
panel air inlet or
rear panel air
outlet, there is
something
blocking the air
flow.
The display
selection is not
right.
It is out of the
synchronization
frequency
measurement
display range.
The signal source
is set to EXT.
A low frequency
(less than 10 Hz)
is set.
9.2 When a Failure is Suspected
Necessary Actions
In the specified clip ratio mode, the
output voltage setting means a value for
the waveform before being clipped. To
set a value for the clipped waveform, set
the Type to the specified crest factor
mode (Type: CF). 4.6
Connect a load within the maximum
output range or decrease the output
voltage setting.
When the signal source is EXT or ADD,
lower the level of the connected signal
generator or decrease the external input
gain.
Decrease the ambient temperature when
using the product. The maximum current
may decrease over 40 °C.
Clean the air filters by referring to 10.2.
Install the product so as to satisfy the
installation conditions described in 2.2.
Select RMS for AC. Otherwise, the
correct value is not displayed.
Set the synchronization signal source
frequency to a value within the
synchronization frequency measurement
display range. 11.11
In EXT, the measurement cycle is fixed,
and thus the difference from the external
signal cycle may fluctuate the measured
value. On the other hand, in the ADD
mode, the appropriate measurement cycle
is decided according to the internal signal
source frequency setting. Therefore, if
you know the frequency of the external
signal to use, change the signal source to
ADD, set the internal signal source
frequency to the external signal
frequency, and set the internal signal
source output voltage to zero. 4.20
For a frequency lower than 10 Hz, the
measurement cycle is a fixed value and
thus the measured value may not be
stable.
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