Megger SMART THUMP ST16, Руководство пользователя

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M
AVTMST16 Rev 1 May 2016
26
How to Pre-Locate the Fault
Arc Reflection Method (ARM)
For pre-location of high resistance fault the SMART THUMP applies the widely
approved and well-known ARM (Arc Reflection Method).
Locating the fault becomes possible by comparing a reflection image taken with a
LV pulse (reference trace) to a reflection image taken while the arc, ignited by
sudden discharge of the charged capacitor, was present g at the fault location
(fault trace). With this method, the two measured traces diverge at the position,
where the arc caused a negative reflection of the TDR pulse, indicating the fault
location.
Proceed as follows to pre-locate the cable fault:
Step Description
1
Select the menu item from the main menu or from the submenu (depends on
the system configuration).
Result: A LV pulse is fed into the cable. The reflection image with the determined
distance to the cable end is presented in the display.
This reference trace is also called “live” trace as it is permanently refreshed (blue color,
a black color trace indicates a “frozen” or “saved” LV trace).
Note: The software provides its best estimate for the cable end. If the trace beyond the flag
“open at 950 ft” does not show any significant upwards or downwards reflection,
then click to confirm. If there is a substantial reflection beyond this point, turn the
rotary to the
, click and adjust the end marker manually to where the end of
the cable is visible, then click to save and confirm.
Either the suggested or the manually adjusted cable end must
be confirmed, otherwise unit will not display any distances.