LANTEK User Manual - Ideal Industries

Chapter 3
Structured Cable Field Calibration and Testing
Capacitance Test
This test measures the mutual capacitance between the two conductors of each wire
pair to verify that installation has not affected the capacitance for the particular cable
type.
‣ Bulk capacitance measurements are displayed in nanofarad (nF) in the Analyze
Capacitance test.
‣ Autotest measures the bulk capacitance in picofarads (pF) per foot or meter.
Capacitance Errors
Figure 3-20: Capacitance Test Screen
The larger the capacitance; the higher the error rate. Small changes in the
capacitance measurements are normal due to the handling of the cable during
shipping and installation. The addition of connectors and patch cables will also affect
capacitance values.
Troubleshooting Capacitance Problems
Problem: Capacitance Exceeds the Maximum Limit
Probable Causes
Compression, stretching, or excessive bending damage to the
cable.
Defective connectors.
Insulation damage at a connector.
Ground loops created between cable shielding (if used) and
equipment grounding (via RS-232 cable to computer, or auxiliary
power).
Improperly chosen cables or patch cords.
Moisture in the cable.
Poor connections at punch downs and wall plates
Other Tests Affected Test Possible Result
Length
Affected pairs will appear longer.
Average Impedance Change in average impedance is inversely
proportional to change in capacitance.
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