Backlight; Tone Generator; Determining And Measuring Vp Values; Attaching A Cable To The Fault Mapper Pro - Chauvin Arnoux CA 7026 Manual De Instrucciones

4.5

Backlight

The display backlight is switched on and off with the button
4.6

Tone Generator

The Fault Mapper Pro™ may also be used as a tone generator, to trace and identify cables
and wires. The user will need a cable tone tracer, such as the AEMC Cable Tone Tracer
(consult factory) or equivalent.
Pressing the TDR/ button will inject a warbling (oscillating) tone into the cable or link
under test. When set, the following will be displayed:
* * * * * * * * * * * * * * * * * * *
Warble Tone
* * * * * * * * * * * * * * * * * * *
The injected signal oscillates between 810Hz and 1110Hz, six times per second.
NOTE: The auto-off function is disabled in Tone Generator mode, so that the tone can be
injected into a cable for an extended period of time while tracing takes place.
.
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4.7

Determining and Measuring Vp Values

Vp, or Velocity of Propagation, values are characteristic of each cable type and brand. The
Vp is used to measure the length of a cable and to measure a fault location. The more
accurate the Vp, the more accurate the measurement result will be.
The cable manufacturer may list the Vp on their specification sheet or may be able to
provide it when asked. Sometimes this value is not readily available, or the user may wish to
determine it specifically to compensate for cable batch variations, or for special cable
applications. This is quite easy:
1. Take a cable sample of exact length increments (ft or m) longer than 60ft (20m).
2. Measure the exact length of the cable using a tape measure.
3. Connect one end of the cable to the Fault Mapper™ (see § 4.9). Leave the end
unterminated and make sure the wires do not short to each other.
4. Measure the length and adjust the Vp until the exact length is displayed.
5. When the exact length is displayed, Vp is established.
4.8

Attaching a Cable to the Fault Mapper Pro™

1. Make sure that there is no power supply or equipment attached to the cable to be
tested.
2. Check that the far end of the cable is either open or shorted (not fitted with a
resistive termination).
3. Attach the Fault Mapper Pro™ to one end of the cable to be tested.
The cable attachment is via a BNC connector located at the top of the unit. For unterminated
cables use the alligator clip attachment provided.
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