Inrush Current Mode; Low Pass Filter - Extech Instruments MA140 User Manual

Inrush Current Mode
In the Inrush mode the meter waits until at least 5A is detected and then starts a 100ms sample
window in which to capture an inrush current RMS value. Refer to illustration below.
1. Press and hold the INRUSH button for > 2 seconds to access the Inrush Current mode.
2. The display will show the INRUSH icon.
3. When ready, take a current measurement. The meter will capture the highest reading
detected during a 100ms window. Note that the 100ms window does not open until at least
5A is detected.
4. To exit the Inrush Current mode press the INRUSH button again momentarily. The INRUSH
icon will switch OFF.
Threshold
Low Pass Filter
The Low Pass Filter mode offers high frequency rejection when measuring Variable Speed Drives.
The Low Pass Filter mode offers a cut‐off frequency of 160Hz (approx.) with an attenuation
characteristic of ‐24db per octave (approx.).
1. Momentarily press the LPF button to access the LPF mode
2. The LPF display icon is shown on the display in the LPF mode
3. Press the LPF button again to exit the LPF mode, the LPF icon will switch OFF
800.561.8187
Inrush
Button
Press
Sample time
trigger
100ms Sample Window
Start
www.
Measured Inrush
Current
Stop
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