Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 93)

Publication GMC-RM001A-EN-P — July 2001
Measuring Noise Reduction Effectiveness 11-3
E-Field Sniffing Method
The E-field is the electric field capacitively coupled to the probe. To
use the E-field sniffing method:
1. Attach a 150 mm (6 in.) length of stiff insulated wire to the probe
tip to form an antenna.
2. Remove the probe ground clip or attach it to the scope cable to
ensure it does not contact anything.
3. Hold the wire parallel to and touching potential victim wiring and
measure the voltage spikes.
Note: The signal observed is with respect to the scope ground. Check
the method by holding the wire against the panel. There should
be little noise observed (refer to the section Ground Loops for
more information).
Figure 11.1
Simple E-field probe