Just as steel rims and inflated tires replaced wooden spokes and rigid rubber tires, fiber optics continues to replace many older and less effective technologies. Fiber optics applications are numerous. Fiber advanced telecommunications in the 80’s by replacing copper wire in phone and cable lines and then innovated medical imaging by relaying vital information from tiny cameras that could be routed deep in the human body to search for diseased organs.
Fiber optic applications at Cleveland Electric Labs Advanced Technologies Group include fiber optic sensors to identify; new higher temperature capacities for turbine engines, the structural integrity of bridges, the imminent failure of structural fasteners (bolts), the means to identify terrorists and intruders, and impact of flight conditions in aircraft.
Fiber optic sensors are being specified versus electronic sensors developed in the 1950’s. All or some of the fiber optic applications noted below require these fiber optics advantages — immunity to EMI, RFI, corrosion, chemicals, high heat or very cold conditions. Fiber is easily routed in tight places, and is very light weight. Fiber optic sensors respond hundreds of time faster than electronic sensors and one fiber trunk line can transmit data from 80 sensors. Electronic sensors require individual connections for each sensor creating a weight concern in addition to the labor that is required.
High Temperature Fiber Optic Applications
Fuel consumption and performance are two critical cost factors for turbine aircraft operators. Every ounce of fuel consumed by either a commercial or military aircraft engine increases operating cost. Jet engines that run hotter are often more efficient because they develop more horsepower and thrust. Fiber optic sensors and interrogators are needed for engine testing because traditional thermocouples, normally used to measure engine heat, cannot respond in fractions of seconds. During engine testing transient temperatures, engine material melt points, and indications of engine surge require instantaneous temperature measurements to avert undesirable conditions and potential catastrophic events. CEL Advanced Technologies Group engineers have developed fiber optic sensors that can withstand sustained temperatures of 1400C, the first high temperature fiber optic sensors ever developed for commercial use
Structural Health Monitoring Fiber Optic Applications
70,000 bridges in the US have been determined “structurally deficient” by the American Association of State Highway Traffic Officials. These and other bridges require frequent inspections, maintenance, and repair. Bridges have been visually inspected for over 80 years and recently ultrasound and electronic devices have been used. However, each inspection method has specific drawbacks and we believe no inspection and monitoring technology can equal the benefits of fiber optics. CELs engineers fiber optic applications that include structural health monitoring plans utilizing fiber optic strain gages, fiber optic temperature gages, fiber optic scour gages, fiber optic tilt and vibration sensors. The sensitivity of fiber optics sensors enable slight changes in aging bridge structures to be evaluated and monitored effectively. Fiber optic sensors and sensor arrays are mounted on a bridge and connected to a fiber optic trunk line. Up to 80 sensors (of different types) can be connected to one fiber and connected to one channel of an interrogator. The interrogation instrument can operated by solar power if no electricity is present. The data gathered is analyzed by a computer and be accessed at the bridge location or transmitted by satellite to a remote monitoring station. Each sensor on the structure can be identified by its individual address on the bridge and each sensor reports its condition– temperature, vibration, strain, tilt etc.
CEL Advanced Technologies Group can provide both the monitoring strategy and provide the fiber optic applications plan plus complete the bridge installation. Various supply companies can provide some of the ingredients required for SHM, but CEL can supply all the requirements; monitoring plan, sensors and interrogation equipment, installation, on-going monitoring and data analysis.
Fiber Optic Applications-Security
Perimeter security is a critical concern for all high value public facilities and private locations. Nuclear power plants, water treatment facilities, and electric utility substations, and other targets need to be protected from intruders. Locations that rely upon fences and video surveillance are frequently violated. Utilities substations are attacked every day and trespassers are being electrocuted as they attempt to steal copper parts from generating and transmission equipment. Lawsuits against utilities are commonplace.
CEL Advanced Technologies Group has fiber optic applications that include buried security cable. The fiber optic cable is so sensitive that when a trespasser steps within 5 feet of either side of the buried cable, the trespassers exact location is registered instantaneously signaling the sub-station monitoring personnel that may be many miles from the substation. Even more important for law enforcement officials, a video camera (that can be concealed from view many yards away) can be trained to immediately focus on the exact location of the violation. The exact intrusion location creates a high probability that the camera can capture the identity of the perpetrator.
Another security product FORRmat, fiber optic rapid response mat, from the CEL Advanced Technologies Group detects illegal entry in locations that use card swiping devices for legal entry. This important fiber optic application is designed to identify “tailgaters,” trespassers without legal swipe-cards. Tailgaters enter a secure facility close behind a legal card holder either by force or by not being noticed by the legal card holder as he or she enters the “secure” facility. FORRmat, the fiber optic rapid response mat from Cleveland Electric Labs detects tailgating. Fiber optic sensors embedded in this non-descript entry mat are sensitive to multiple weight points that simultaneously compress the sensors. The mat can detect the weight of two persons or four footprints where the weight of only one person or two footprints should be sensed. The FORRmat fiber optic sensors signal a violation and in an instant a video camera aims at and records the incident. Sensors notify security personnel of an unlawful intrusion.
A long series of FORRmats, manufactured similar to the above fiber optic application is capable of detecting transit station encroachment. Across the world transit authorities are threatened by persons who attempt suicide by jumping in front of oncoming trains, or attempt to de-rail trains by placing explosives on tracks. The FORRmats fiber optic sensors, and the accompanying interrogation system, immediately detects transit violations and trains a video camera on the track at the exact location of the violation to alert authorities of an impending catastrophe.
Fiber optic Applications-Structural Fasteners-Bolts with Brains
Each year thousands of bolts (structural fasteners) yield or break as they connect steel and other materials. Used in tunnels, bridges, buildings, cranes, and heavy equipment, fasteners are critical to structural integrity and until now the ability to predict failure has been impossible. Now with the advent of Cleveland Electric Labs Brainy Bolt, a fiber optic insert located inside the fastener shaft, can detect strain, elongation, and tension on the bolt. The insert is a fiber optic strain gauge and when connected to an interrogator and an industrial computer the light waves are scanned and changed into digital messages regarding the load and stress on the bolt. A 5/8” bolt can supply clamping loads as high as 30,000 pounds. The Brainy Bolt is capable of detecting load changes of less than 1% of the maximum load.
