Low Pass Filter (Model 289 Only) - Fluke 289 User Manual

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Users Manual

Low Pass Filter (Model 289 only)

The Meter is equipped with an ac low pass filter. When
measuring ac voltage, or Vac frequency, press the softkey
labeled Menu to open the function menu, and move the menu
selector to the l item. Next, press the softkey labeled
l to toggle the low pass filter mode on (l displayed)
and off.
XWWarning
To avoid possible electric shock or personal
injury, do not use the Low Pass Filter option to
verify the presence of hazardous voltages.
Voltages greater than what is indicated may be
present. First, make a voltage measurement
without the filter to detect the possible presence of
hazardous voltage. Then select the filter function.
The Meter continues measuring in the chosen ac mode, but now
the signal passes through a filter that blocks unwanted voltages
above 1 kHz, as shown in Figure 8. The low pass filter can
improve measurement performance on composite sine
waves that are typically generated by inverters and variable
frequency motor drives.
In Low Pass Mode, the Meter goes to manual mode.
Select ranges by pressing R. Autoranging is not
available when the Low Pass Filter is enabled.
20
Note
1 kHz
100 Hz
Figure 8. Low Pass Filter
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