SYStronics AC-3301L, User Manual, Page: 20 / 21

AC-3301L MANUAL
20
Isolation operation for cable noise
Isolation operation for cable noiseThe wiring of the microcomputer input / output wiring and the AC input
terminal must be separated from each other to prevent noise from occurring.
Precautions
The noise filter of the AC input terminal of the microcomputer must be separated from the input / output wiring
of the noise filter (the noise filter function is seriously degraded when integrated wiring is installed), and the
output terminal should be connected to the nearest position to the microcomputer.
Contact noise suppression method
MC's contactor coil, relay coil, transformer circuit, solenoid coil, cabinet Fluorescent lamp, etc. can be reduced
by applying a noise suppressing capacitor. Contact noise for an AC circuit controlled by a switch such as a
contactor coil or a relay coil requires an RC suppressor circuit at either the coil's positive or negative terminal
or an equivalent snubber capacitor. Generally 100Ω and 0.1Uf are connected in series, but it needs to be
adjusted according to the load power.
How to Identify the Source of the Noise Source
This is an oscilloscope-based measurement of noise peak inductance, as a method of directly measuring
noise in the field.
1. Induced peaks are short and the amplitude varies greatly with time, which is often difficult to measure.
2. On the oscilloscope, set the time axis to 1us / div and set the trigger to capture the peak.
3. Slowly increase the trigger level until triggering stops to measure the maximum peak voltage displayed.
4. Connect the probe grounding clip of the oscilloscope to the probe tip to form a small loop.
5. In the indirect measurement of the cable, the loop probe antenna is sensitive to the direction, so you
must measure the position by capturing the maximum value and fixing the probe.
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AC input terminal wiring Input / output signal AC input terminal wiring Input / output signal