Calibrate Cable Resistance - RLE Technologies LD5200 User Manual

2.8

Calibrate Cable Resistance

Distance-read leak detection systems are resistance-based. RLE's orange water sensing cable
has a base resistance of 2.8 ohms/foot, while most other sensing cables, including RLE's green
chemical resistant sensing cable, have a resistance of 4.0 ohms/foot.
The resistance of each length of sensing cable may be slightly more or less than the base
resistance due to manufacturing variances. For this reason, the cable length displayed on the
home page of the web interface and on the status screen of the LCD may be slightly more or
less than the actual length of cable installed.
A system configured using base resistance values will still be very accurate. If you wish to fine
tune the resistance value of your LD5200 system to make it more precise, you may do so. This
will increase the accuracy of the system, and bring the LD5200's reported installed cable
length value in line with the actual length of cable installed.
Ensure the LD5200 has been powered and has all the sensing cable attached to it, with no
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alarms present.
Gather and record the following data from either the home page of the web interface or the
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status page of the LCD:
Cable Length (as reported by the LD5200)
Cable Current
Leg 1 Resistance
Leg 2 Resistance
Record the resistance per foot setting, as reported by the LD5200. This can be found on the
Leak Configuration page of the web interface (Configuration > Leak Settings) or on the
Leak Settings screen of the LCD (Setup > Leak Settings).
Reported Resistance per Foot
Note the actual (physical + simulated) length of cable physically connected to the system.
3
For your reference:
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WCCS simulates 50 ft.
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SDZ simulates 50 ft.
Record this sum:
Actual length of cable connected to LD5200
Verify the current reading on the cable from your recorded values above. This value must
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be less than 15 μA in order to calibrate the system. If the current is higher than 15μA, clean
the cable. Isopropyl alcohol works well to remove any contamination that might have
gotten onto the cable during installation.
rletech.com
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LD5200 User Guide
XCON simulates 150 ft.
Nonsensing cable does not add
any length to a system
2 Installation
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