Chapter 7: Service and troubleshooting
204 EST3X Technical Reference Manual
After opening the loop, if the GND Fault LED goes out, the ground fault is located
on the portion of the loop that has been disconnected. If the LED remains on and
no devices restore, the short has been isolated to the first 50% of the loop.
Reconnect the previously isolated portion of the loop, and then open the loop at a
new point. If during the first isolation process the GND Fault LED went off, open
the loop at a location electrically farther from the loop controller, and then repeat
the analysis. If during the first process the GND Fault LED remained on, open the
loop at a location electrically closer to the loop controller, and then repeat the
analysis.
Continue increasing or decreasing the number of devices on the opened loop leg
until you will isolate the device or wire segment causing the problem.
Notes
• The ground fault detection circuitry requires approximately 30 to 40 seconds
response time when the fault is removed.
• The EST3X control panel performs a ground fault test for 2 seconds at
18-second intervals. If the system is working properly, the voltage between
earth ground and logic negative should be between 12.3 VDC and 16.8 VDC
during the 2-second test. The system reports a ground fault when the
voltages are less than 12.3 VDC and more than 16.8 VDC. In a non-faulted
system, the voltage outside the 2-second test period may float randomly. If
the system is faulted, then the voltage is likely to be a fixed value such as 3 or
19 VDC.
Substituting Signature Series devices
When substituting a known good detector or module in place of a suspect device,
the following scenarios can take place.
1. If the substituted device is the same model as the suspect device, the system
accepts it with no further operator action. When the substituted device is
installed, the system goes into trouble. When the quantity of devices defined
on the loop is reached, the system automatically remaps the loop, stores the
revised information, and returns to normal. This process may take a few
minutes.
2. If the substituted device is a different model than the suspect device, when
the device count is correct, the Signature controller module automatically
remaps the loop. A trouble occurs at the address of the suspect device as the
result of a map fault because the known good device’s parameters differ from
those of the removed suspect device. You must accept the parameters of the
known good device to remove the fault. These can be changed later.
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