SECTION 4: INSTALLING THE CONTROL4-31Using the VPLEX-VSI Short IsolatorThe VPLEX-VSI Short Isolator provides short circuit isolation for V-PLEX devices. When a short occurs on a polling loopbranch, it illuminates a trouble LED and isolates the defective branch from the system, reducing troubleshooting time.1. Detects and isolates polling loop branches with complete or resistive shorts, and overload or defective VPLEXdevices on initial power up;2. Can be used to isolate loops, such as burglary devices from fire devices (see example below);3. LED indicator reduces troubleshooting time and has low power consumption, powered directly from the V-PLEXtwo-wire polling loop;4. Can be placed on any major or minor branch in any configuration on the polling loop.The VPLEX-VSI automatically returns to normal operation and the Trouble LED is extinguished, when the troublecondition on the output side of the VPLEX-VSI is rectified.A control panel normally reports a short on a polling loop as a trouble on zone 997. When using the VPLEX-VSI in aproperly configured polling loop, this trouble condition will not occur. Instead, the zones isolated by the VPLEX-VSI willreport in trouble. A few panels do not have any delay on reporting a polling loop short as a trouble. With these panels, a997 trouble will be reported for a polling loop short. Otherwise, operation is as described above.Figure 31: VPLEX-VSI ExampleV-PLEX® Smart Contact TechnologyAutomatic suppression of fault/restores when disarmedSmart V-PLEX sensors such as the DT7500SN, and IS2500SN polling loop motion detectors can be set to stopsending fault/restore signals while the partition is disarmed. This prevents a degradation in polling loop response fromslowing down due to high bus activity in busy areas. The feature is enabled by Zone in ∗93 Zone Programming.When enabled, within approximately 5 minutes of program exit, the panel will send the command to the SmartContacts to turn off their LED and stop sending faults/restores to the system. (The DT7500SN and IS2500SN will turnoff their LED unless the LED DIP switch is set to ON, in which case the LED will always remain enabled.)
