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  • Detection of condensation in fiber optic splice cases
  • Determination of water in normally dry areas
  • Warning of sump pump failure

Fiber Optic

Moisture Detector

To ensure the performance characteristics of fiber optic transmission lines, the presence of water, and in particular, ice must be detected and corrected. To accomplish this effectively and economically, TX Technology Corporation has developed a Fiber Optic Moisture Detector, which operates on the principle that upon contact with any water-based liquid or spray, a sharp decrease in resistance will occur. The sensor which is normally open (high electrical resistance) will quickly read short in the presence of water. The moisture detector is well suited for most applications.

Once the moisture conditions has cleared, the sensor is self-restoring without wear or degradation and is ready to report the next incursion.

Because of the limited number of monitoring pairs in fiber optic transmission systems, most applications are based on addressable technology where multiple sensors may be placed on a single monitoring pair. For non-addressable applications, please consult the factory.

TTX addressable moisture detector is capable of sensing the presence of moisture anywhere along its five foot length. Other lengths can be special ordered for additional coverage. In its two bank configuration it can read one or two different sensors and report as little as two or three drops of moisture for up to 100 miles over a single pair of wires. In the ten bank configuration, up to ten sensors can be read per logic module.

By installing a 4MΩ resistor in parallel with the sensor, we can guarantee a normal dry (level 20) reading, thus ensuring that the line integrity is maintained.

When moisture occurs, the sensor will decrease its electrical resistance, therefore causing the combination resistance to drop constantly.

The level can be programmed in by the user to determine the level which will cause the alarm. Level 1 being highest humidity level, while level 20 is the lowest.

Typical application


  • The sensor is a solid-state device and is not susceptible to mechanical failure
  • The sensor is comprised of low-cost materials
  • The sensor can be in direct contact with the underground environment without degradation of loss of performance
  • The sensor is reversible, i.e., it will return to its normally insulating state upon elimination of its humidity
  • The sensor acts as a simple electronic component and is readily integrated into an existing TX Monitoring System
  • The sensor acts as a distributed sensor, i.e., it detects the presence of water at any point along its length (length can range up to several hundred feet)


Up to one thousand moisture sensors (TTX type) can be read with a TX L3 Monitoring and Control System in any of the following combinations:
  • Up to 4 TT cards per system
  • Up to 8 TTX cables per card
  • Up to 4127 TTX Modules per cable
  • Up to 10 moisture sensors with TTX 5/10 Bank Moisture Detector Module
  • Up to 2 moisture sensors with TTX 2 Bank Moisture Detector Module

7 Emery AvenueRandolph, New Jersey 07869973.442.7500
1.800 CHATLOSFax: 973.442.7575info@txtechnology.com


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