2 Operating PAL-AT
10
CONNECTED TO ZBA TO MONITOR HC?
ENTER * FOR YES, # FOR NO
The baseline is a number between 25 and 35. If the unit displays a value outside this range, it shows a
hardware failure. If so, contact PermAlert for assistance.
2.1.4 Hydrocarbon Liquids with ZBA
Next PAL-AT displays the message:
LCD2.1-04:
Caution: If a cable or probe is monitoring for hydrocarbon liquids (gas, oil, fuel, solvents,
etc.) located in a classified or hazardous area, the cable must be connected to a Zener
Barrier Assembly (ZBA) in a Zener Barrier Panel (ZBP).
The ZBP and ZBA are also installed for cables in non-hazardous areas to protect the panel from external
high voltage spikes. Typically, this is for areas with a high frequency of lightning strikes near the leak
detection cables.
2.1.4.1 Impedance Jumper Setting
Before beginning the next step in the Setup process, check the impedance jumper position. Refer to
figures 1-1 and 1-2 for positioning the jumper. The 2-pin jumper should be in position A, B, C, or D
according to the type of cable and whether the cable is connected to a Zener Barrier Assembly.
Jumper Position Cable Type Zener Barrier Ass’y Installed
A ATP only No
B ATP only Yes
C All others No
D All others Yes
2.1.5 Sensor String Sections
The sensor string is a combination of lengths of jumper cable, sensor cable, and probes connected in
series to PAL-AT and monitored for leaks, breaks, etc. During the setup function, the sensor string is
broken into several sections. The end of each section is a calibration point. Two general rules determine
the required number of sections or calibration points.
The first rule requires a new section or calibration point at every change in cable type. For example,
a sensor string consisting of 50 ft [15 m] of jumper cable, 400 ft [120 m] of AGW-Gold cable, and then 20
ft [6 m] of jumper cable is set up as three sections. There may be several cable connectors within one
section. The 400 ft of AGW-Gold may consist of 10 lengths of cable, each 40 ft [12 m] long, but they
should be connected and entered as one section.
An exception to this rule is if the length of a cable is 15 ft [5 m] or less. For example, one area of a
sensor string has 200 ft [60 m] of AGW-Gold, then 15 ft [5 m] of jumper going through a manhole, and
finally 200 ft [60 m] of AGW-Gold. The 15 ft jumper cable should be added to the beginning of the second
200 ft of AGW-Gold and these two lengths of cable are setup as one section of AGW-Gold. In this example,
the first section is 200 ft, AGW-Gold, and the second is 215 ft, AGW-Gold.
The second rule concerns long lengths of one type of cable. Make additional calibration points at
cable connectors approximately every 500 ft [150 m]. Consider a sensor string consisting of 50 ft [15 m]
of jumper, 700 ft [215 m] of AGW-Gold, and 20 ft [6 m] of jumper. Instead of setting the cables up in three
sections, make an additional calibration point in the 700 ft [215 m] of AGW-Gold to improve the accuracy
of the system. In this example, the 700 ft [215 m] of AGW-Gold should be 2 sections, approximately 500
ft [150 m] and 200 ft [65 m] long.
The setup procedure requires the sequential addition of sections to the sensor string and should
be planned carefully to assure an accurate calibration.
2.1.6 Create Setup Table
The next message asks for data about each section of the sensor string. PAL-AT uses it to create a setup
table. For each cable section, PAL-AT requests: (1) the type of cable and (2) the cumulative distance
to the end of the section.
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