Welcome to VESnet Wired
Welcome to the first ever VESnet Wired. Stay tuned to VESnet Wired to receive more technical aspects of our fire detection equipment including, firmware updates, application notes, Tec-tips and much more.
Does your customer require a simple way to periodically disable a specific group of devices?
Did you know that a disablement is a powerful and straight forward programming option? Disablement functionality may be achieved remotely or at the panel without your customer having to search through panel menus?
Achieving a Disablement—
- Connect a key-switch to one of the input modules (either on the SLC loop or built into the panel [based upon panel type]).
- When programming the input module (whether using eSP Discovery or Loop Explorer software), choose “General Purpose” as the Device Setting and “Disablement” as the Input Action.
- Create a “relationship” or “cause and effect” (depending on which programming software you are using), and choose “Disablement” as the type. Select your input module as the “cause” and any devices that the customer wants to disable as the “effect”.
Once the program has been sent to the panel, the customer will simply have to turn the key in the key-switch in order to achieve the desired disablements.
Troubleshooting Ground Faults
Troubleshooting panel-reported ground faults on an installed system can be challenging. The best way is to start disconnecting parts of the field wiring at the panel. Almost any wire that leaves the cabinet is suspect except for the AC power. SLC loops and NAC circuits are most common, although AUX24V power, fire routing, trouble routing, programmable outputs and network cables are also possible sources. The difference is the SLC and NAC runs are generally longer, with more connections and so are more prone to the faults in general.
Disconnect circuit after circuit until the fault indication clears. Each time you disconnect a circuit, disconnect all the wires related to the circuit. In other words, disconnect both (+) and (-) of a NAC, all four connections of a Class A SLC loop, etc.
The panel heavily filters the ground fault reporting. This helps prevent spurious momentary indications, but delays the reporting of the fault (or restoral) by up to a minute. This severely hampers the diagnosing of the problem. It is natural to connect/disconnect a circuit and expect to see the impact (fault/restore) immediately. It doesn't!
However, there is a way to see the results immediately. It requires a Multi-meter or DMM.
- Set the meter on an appropriate range to measure 0-24VDC.
- Connect the black meter-lead to the black battery-lead of the panel.
- Connect the red meter-lead to the ground-stud of the panel or any good earth ground.
On an eLAN or Elite panel...
Under normal conditions the meter should read in the range of 10-14 volts. Under a ground fault condition the reading will be either above or below this range depending on the type of fault.
On an eLAN RS or Elite RS panel...
Under normal conditions the meter should read in the range of 6-18 volts and will be constantly moving. The reading should move up from about 8 to about 16 volts and then back down and repeat. One cycle takes about 6 seconds.
Under a ground fault condition the reading will either not move or move in a different range. (Narrower range, wider range or range above or below this range depending on the type of fault.)
Monitor the meter reading, not the panel's ground trouble indicator, as you are connecting and disconnecting each of the field wiring circuits. When you see the meter-reading change to the normal reading (as described above) you have isolated the circuit with the ground fault. Once you have isolated the offending circuit, the ground trouble indication on the panel should restore within 60 seconds.
At this point, any other circuits should be able to be re-connected without resulting in the meter changing from the normal reading or the ground trouble indication reoccurring.
You have located the faulty circuit. Now you must locate the actual fault. With the circuit still disconnected from the panel…
- Disconnect the black meter-lead from the battery.
- Change the meter to a continuity or ohms scale.
- Momentarily touch the black meter-lead to each wire of the faulty circuit and determine which has the lowest reading. This wire, most likely, is the faulted wire. (Note: If the faulty circuit is a Class A SLC loop, both ends of this wire (IN/OUT+) or (IN/OUT-) will have similar readings. If both ends read < 100 ohms, the ratio of the readings may help provide some insight as to the location of the fault.)
- Monitor the meter reading as you disconnect different sections of the faulty circuit from the panel. If you break the circuit half way between the panel and the end-of-line and the fault clears (reading goes to > 100k) the fault is between your break and the end-of-line. If it does not change, the fault is between your break and the panel. Keep dividing the circuit until you isolate the location of the fault.
Congratulations to Tom Robertson of Affordable Fire Solutions who is the winner of our iPAD competition.