VTW-400 – Electronic Tautwire Fence

DeTekion Security Systems, Inc. is the U.S. manu-facturer and distributor of the VTW-400 Electronic Taut Wire Fence Intrusion System. The VTW-400 Taut Wire is a highly reliable perimeter detection system. Barbed Wires are strung taut between anchor posts and clamped to the VTW-400 sensor post. The VTW-400 Taut Wire is a physical barrier that will annunciate an alarm condition under attempts of intrusion by:

• Climbing
• Spreading
• Cutting

The VTW-400 utilizes the latest technology to create a perimeter detection system with the highest probability of detection, lowest false alarm rate and lowest maintenance of any perimeter detection system on the market.

STW-40 Sensor

DeTekion Security Systems, Inc. patented Sensor design uses multiple strain gauges and state-of-the-art miniature circuitry to provide a highly stable and accurate Sensor signal. The VTW-400 Electronic Taut Wire Fence System utilizes a sophisticated design employing bridge-compensated strain gauges as sensing elements and a powerful microprocessor based alarm processor. Movement of the taut barbed wires in any direction causes flexing of the composite structure of the Sensor’s flexible circuit board. This flexing causes the Sensor’s strain gauge to generate a signal to the FP-400 Processor as a very precise indicator of the movement of the barbed wire. The miniature sensor circuit board is mounted inside the specially designed rubber housing, sealed from the environment, and connected to the processor via a three pin connector at the base of each Sensor. One end of the Sensor has a slotted, threaded stud. The Taut Barbed Wire is fitted in the stud slot and clamped to the Sensor by a nut. All exposed hardware is Stainless Steel.

FP-400 Processor

A small, but powerful, microprocessor constantly monitors up to 32 sensors. Through multiple sensor sampling and multiplexing, the FP-400 processor determines the validity of an event and if the sensor value is outside a stored window of normalcy, the FP-400 reports an alarm by activating an internal alarm relay. The FP-400 processor uses a dual window alarm capturing system. If a taut barbed wire is cut, or if any internal wiring is broken, a trouble alarm relay is activated. The remaining fence post sensors will still be functional and able to report alarms. Trouble alarms are automatically reset after the trouble condition is corrected. The design also allows the taut wire system to self-adjust for environmental conditions and to provide for various levels of sensi-tivity (user programmable) of the individual sensors. This technique practically eliminates false and nuisance alarms. An available option can monitor which “side” of a Sensor is stressed, allowing one Sensor to monitor two 50 meter Zones simultaneously.

On-board diagnostics allow a maintenance technician to easily troubleshoot the activity of the Processor. The Actual Reading, Long Term Average, Alarm and Trouble states, and Set Points for each sensor can be displayed at any time. It is not necessary to take the unit out of service for the diagnostics.

The FP-400 processor has the added advantages of small size, 8′′ x 6′′ x 1′′ and low current requirements, 200 milliamps of current (10-30 VDC). The FP-400 processor is factory mounted in a NEMA enclosure and
this enclosure is typically mounted directly to the sensor support post. Conduit stub-ups to large electrical junction boxes adjacent to a fence are significantly reduced.

Basic Configuration
The VTW-400 Taut Wire Detection System is custom tailored to client specifications. The sensor post can be designed to accommodate coverage of almost any area needing protection. The most common designs are:

• Straight post
• Single outrigger
• Dual outrigger
• Combination of straight post and outrigger

The VTW-400 Taut Wire Detection System can be mounted as a stand-alone system, mounted on an existing fence, or mounted on a wall or roof. Sectors can extend up to 100 meters. A zone can be one sector or several sectors wired together. Each sector requires an anchor post at each end, one sensor post with processor in the center of the zone, and slider posts spaced 10′ (3 meters) on center. Barbed wire is strung taut between the anchor posts and clamped at the sensor post. Wire tensioners maintain the proper tension on the wires.

The spacing of the sensors is custom tailored to each
individual project. The overall gap between wires for alarm activation should be considered in the design of the taut wire system. It is critical to design the sensor post wire spacing so that an alarm will activate before the gap between the wires reaches the alarm parameters for the project. The software of the VTW-400 taut wire system has the unique capability to adjust the sensitivity of each sensor. This sensitivity adjustment allows the client to manipulate the alarm parameters between any two wires