8-4
Earth fault diagnostics
Overview This section contains instructions on how to use the Earth Fault Search feature of the 4010ES
diagnostics menus. The minimum earth fault detection level for the 4010ES is 10 KOhms for
all circuits.
Earth Fault Search is a diagnostic search of external field wiring that assists in locating circuits
with earth faults. An earth fault occurs when an electrical circuit is shorted to ground. Although
most circuits operate with a single earth fault, multiple earth faults can disable
communications. Because of this, earth faults must be located and repaired.
Earth Fault Search is conducted by the FACP. The diagnostic may be activated using either the
front panel interface or the computer port protocol (CPP), via a service port.
The 4010ES supports two types of Earth Fault Searches:
• Location Search. Searches all circuits at a location, such as a transponder or the main
panel. For the purposes of earth fault searching,
- A location is composed of a group of slaves connected to each other via 4010ES comm
(local RUI).
- The main panel is defined as all slaves local to the Master CPU.
- A transponder denotes all slaves associated with a single Transponder Interface Card
(Remote InfoAlarm or 4009 TPS).
• IDNet Channel Search. Selectively enables channel isolators and repeaters to detect
which segment of the channel wiring has a fault. Earth faults are detected by one of the
following:
- A single designated power supply at a location. The power supply that detects the fault
is designated via a jumper setting on the power supply slave. For any given location,
only one power supply should detect earth faults.
- Each 4009 IDNet NAC Extender on an IDNet channel.
General
guidelines
Review the guidelines below before initiating an Earth Fault Search.
• The Detect Earth Fault jumper (P3) must be installed at the MSS for earth fault detection
to occur. See Table 2-12 in Chapter 2 for details on that jumper.
• Only one power supply per location is configured to detect earth faults.
• For more reliable earth fault searching:
- Use IDNet channel isolators to isolate channel faults to a specific segment of channel
wiring.
- Set IDNet channel isolator addresses to the lowest IDNet device addresses, increasing
with communication distance from the IDNet card.
• If an earth fault is suspected on the IDNet channel with multiple isolators, start an IDNet
Channel Search before doing a Location Search. If the Location Search is done first, it
may not yield the correct location (this is a by-product of the extended amount of time
required for the IDNet channel to initialize during a Location Search).
Note: The 4009 IDNet NAC Extender has a common ground fault trouble that reports to the panel without
running the Earth Fault Search.
• Earth Fault Search detects only one fault at a time. Multiple faults require fixing the first
fault and then repeating the search.
• The FACP suspends normal operation for the duration of the Earth Fault Search.
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