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Download ADT490 TroubleShooting Shorts 2 Shorts With a Ohmmeter Two
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Transcript
ADT490 TroubleShooting Shorts Shorts ‣ ‣ With a Ohmmeter Two types ‣ ‣ Loose wire -> Ohmmeter sees ‣ One side open ‣ One side short Bridging -> Ohmmeter sees ‣ Short from both side 2 Detection - Wire to Wire Short 3 Detection - Wire to Wire Short ‣ ‣ ‣ False Alarm Determined after detection devices eliminated Panel can’t tell the difference 4 Detection - Wire to Wire Short ‣ ‣ ‣ ‣ ‣ ‣ Was work done in the area Worker drilled through raceway Water leakage in the building Insulation stripped from the wire when pulled into the raceway If know wire size, can estimate locations 18AWG -> 6.4Ω per 300 m 5 Detection - Wire to Wire Short 6 Calculations ‣ ‣ Circuit is two wires Circuit 6.4 Ω, then Lw is 300 m and Lc is ‣ ‣ Circuit is 4Ω Lc is 7 Calculations - Need “As Builts” 8 Loose Wire Short 9 Supervisory - Wire to Wire Short 10 Signal Circuit Shorts Terminal Labels - > Trouble 11 Boolean Searches for Shorts ‣ With a short, checking for voltage -no voltage gives no information 12 Boolean Searches for Shorts 13 Boolean Searches for Shorts ‣ ‣ ‣ ‣ ‣ ‣ Remove positive lead from device Voltage increase (may require panel reset) ‣ ‣ Reset may reactivate signals If signals disabled -> MAKE SURE SIGNALS ENABLE BEFORE YOU LEAVE Measure voltage at the device (should increase) Fault is on the EOL side of the Test Point If short on panel side, voltage remains 0V Using resistance measuring may give additional info 14 end of presentation 15