Switchgear Temperature Monitoring

switch-gear-rack.jpgOSENSA’s cost-effective fiber optic sensors provide continuous real-time monitoring of switchgear temperature at critical contact points to quickly detect over-load and fault conditions. OSENSA’s FTX series signal conditioners offer both analog output and RS-485 Modbus communication for simple integration with existing PLC’s and host monitoring software. OSENSA’s optical temperature sensors provide years of accurate sensing to ensure safe and efficient switchgear operation.

Utility companies around the world are implementing fiber optic sensors for smart grid temperature monitoring of critical medium and high voltage switchgear. These sensors provide real-time temperature data, enabling operators to maximize load efficiency and balance thermal stresses that can lead to catastrophic failures. Over time, switchgear contacts, bus bars, and critical connection points develop hot spots that slowly corrode causing increased electrical resistance. If left unchecked, even minor increases in resistance can quickly grow out of control as higher resistance creates hotter conductors, which, in-turn, creates higher resistance. Transmission and Distribution (T&D) companies therefore routinely specify the requirement for continuous switchgear temperature monitoring to optimize maintenance schedules and extend equipment lifetime.

One of the challenges, however, has been to find a cost-effective technology for high voltage sensing applications. Various RF (radio frequency) wireless and IR (infrared) thermometer sensors have been used, but each has its deficiencies. The RF transmitter/receiver sensors suffer from the inherent noise & interference that exists in a high voltage environment, and can lose signal or show temperature spikes during switching operations that may lead to false alarms. Also, because these sensors use electronic components, their temperature range is typically limited to below 120°C for long-term use. Remote IR temperature sensors fare similarly because they require shielded electrical wiring and special mounting points with precise spatial alignment to the object surface being sensed. Infrared thermometers are known to report temperature shifts due to dust accumulation and emissivity changes caused by subtle surface corrosion, especially on shiny metallic surfaces such as copper bus bars. The reported temperature can be skewed by reflected infrared energy emitted by surrounding objects, and sudden changes in ambient temperatures can also introduce measurement error.

OSENSA’s fiber optic temperature sensors do not suffer any of the technical challenges associated with wireless and infrared thermometers. Fiber optic sensors can be routed directly to critical switchgear monitoring points. OSENSA’s low-cost optical temperature sensors are rigidly attached to hot-spot locations, and are completely immune to electromagnetic interference and noise bursts caused by high voltage switching. OSENSA’s fiber optic sensors are robust, can be manufactured to various lengths, and work like a conventional thermocouple. Best of all, each OSENSA optical temperature sensor transmitter can monitor three phases providing both analog output and digital RS-485 Modbus RTU communication. OSENSA’s fiber optic temperature probes are perfectly suited for smart grid switchgear temperature monitoring.

Transformer Winding Hot Spot Temperature Monitoring

transformer.jpgOSENSA’s fiber optic temperature sensors are completely immune to EMI/RFI and high voltage environments making them ideal for transformer winding hot spot temperature monitoring. OSENSA is developing technology and partnering with leading transformer manufacturers that require accurate, real-time, smart grid temperature monitoring of power and distribution equipment.

Fiber optic temperature sensors have been installed in high-voltage oil filled transformers for over twenty years and are now considered the preferred method of transformer monitoring. The benefit that fiber optic sensors offer transmission and distribution (T&D) companies is financially significant. By monitoring temperatures at each transformer winding hot spot, utilities are able to operate the transformer at peak capacity, without extending into overload conditions that can dramatically reduce the life of the transformer. This efficiency both in transmission throughput and service life can translate into savings of tens of thousands of dollars annually, and make direct winding temperature sensing capability a must-have.

OSENSA’s low-cost fiber optic temperature sensing technology makes smart grid transformer temperature monitoring even more compelling. Optical temperature probes are designed from high-dielectric strength materials such as Teflon and polyimide coated silica fiber so that they can withstand long-term immersion in transformer oil and kerosene desorption during manufacturing. A special tank wall feed-through is used to transmit the fiber sensor signal from the OSENSA optical temperature transmitter to the probe installed directly at the transformer winding hot spot locations. OSENSA’s three channel fiber optic temperature sensor signal conditioners are mounted in an external control cabinet with the temperature outputs fed into real-time monitoring and control software. With OSENSA’s optical temperature sensors installed, operators can monitor load conditions in real-time, reducing waste energy production and reducing the environmental burden.

Generator Winding Temperature Monitoring

generator.jpgOn-line fiber optic temperature monitoring is now commonplace for medium and high voltage generator equipment. OSENSA’s fiber optic sensors offer a cost-effective solution for real-time temperature monitoring enabling equipment to operate at peak performance with extended service life.

Fiber optic temperature sensors are now routinely installed into large motor and power generator equipment to provide real-time monitoring and thermal protection of critical stator windings and bearing hot spots. The safe operating temperature of rotating machine windings is limited by the heat which the insulating material can stand before eventual deterioration. This temperature and deterioration rate varies with different classes of insulating materials. Insulation deterioration at a given temperature is approximately proportional to the length of time that the temperature is above the critical threshold. Until recently RTD’s (resistance temperature detectors) were typically embedded into windings to provide continuous monitoring. Now, with advancements in fiber optic technology, low-cost fiber sensors are being employed.

OSENSA’s cost-effective fiber optic temperature sensors can be installed where high voltage and alternating electromagnetic fields pose problems for traditional RTD winding sensors. OSENSA’s fiber sensors can be sandwiched between the windings of motors and generators and allow for continuous temperature measurement to protect insulation and extend maintenance schedules. With OSENSA’s optical temperature sensors installed, operators can monitor load conditions in real-time, maximizing energy and economical efficiencies. Better energy efficiency is good for business and good for the environment.

MRI Temperature Sensing

mri-application.jpgVarious life sciences and patient monitoring applications require high-accuracy fiber optic temperature sensing. OSENSA offers single and multi-channel fiber temperature probes for MRI, NMR, and RF environments, including low-cost disposable temperature probes with fast-response and exceptional accuracy.

Various life sciences applications rely on fiber optic temperature sensors for high accuracy sensing in environments that are not conducive to standard thermometers and RTD’s (resistance temperature detectors). One use for fiber optic sensors is patient monitoring in MRI (magnetic resonance imaging), NMRI (nuclear magnetic resonance imaging), and MRT (magnetic resonance tomography) environments where extremely high magnetic fields combined with pulsed RF (radio frequency) energy prohibit the use of metallic sensors. Fiber optic sensors may be constructed from non-metallic materials making them ideally suited for monitoring patient temperature and insuring the specific absorption rate of tissue does not exceed damaging levels. Fiber optic temperature sensors may also be used to monitor the cryogenic cooling of superconducting electromagnets. Other applications for fiber optic temperature sensors include RF (radio frequency) physiological studies with animals, catheter sensors, and patient monitoring during electro-surgical procedures.

OSENSA offers high-accuracy fiber optic temperature sensors in a range of sizes and materials that are well suited for MRI and CT (X-ray computed tomography) research. OSENSA’s probes can be constructed out of x-ray transparent materials and with non-magnetic connectors for full compatibility in MRI and CT scanning rooms. In addition, fast-response, ultra small diameter fiber optic probes may be specially designed to meet the requirements of many demanding applications.

Semiconductor Chuck Temperature & Process Control

semiconductor.jpgOSENSA’s high-accuracy fiber optic temperature sensors have been designed specifically to meet the demanding requirements of semiconductor process control applications. OSENSA offers fast-response custom OEM solutions for both contact and non-contact optical temperature sensing for dielectric and conductor etch applications. Fiber optic sensors are embedded into the electrostatic chuck in multiple zones to provide maximum control and thermal uniformity.

Many semiconductor wafer processing applications rely on fiber optic temperature sensors for precise process control in high RF (radio frequency) and plasma environments. In a typical processing application a silicon wafer is placed onto an electrostatic chuck that is rapidly heated and cooled in a plasma environment. Fiber optic temperature sensors are embedded into the base of the electrostatic chuck and provide high-accuracy, fast response for tight process control. Each electrostatic chuck is divided into multiple zones, requiring multiple fiber optic temperature sensors to maximize temperature uniformity across the surface of the wafer. Semiconductor applications employing this type of arrangement are typically dielectric and conductor etch processes.

For enhanced plasma chemical vapour deposition (EPCVD) processes, a shower head reactor is used to disperse reactant gasses into the process chamber while intense RF energy is applied. In these applications, fiber optic temperature sensors are employed to control the shower head temperature as well as monitor side wall temperatures to minimize deposition on internal chamber surfaces. OSENSA’s fiber optic temperature sensors were developed specifically to support a wide variety of leading-edge semiconductor processes. OSENSA’s fiber optic sensors may be constructed in non-contact geometries where the sensing material is embedded into the base of the electrostatic chuck, but with the optical fiber positioned remotely. This method maximizes response speed and eliminates stem conduction losses. It also makes e-chuck replacement and refurbishing simpler, avoiding the risk of broken fiber optic temperature probes.

OSENSA’s fiber optic temperature sensors may also be employed in high-vacuum environments with direct plasma exposure. In this case, special fiber optic temperature probes are constructed from materials which present low ionic contamination and minimal plasma erosion.

Microwave and Induction Heating Control

microwave.jpgOSENSA’s multi-channel fiber optic temperature sensors offer cost-effective and convenient temperature monitoring of industrial microwave processes including microwave assisted chemistry, microwave sterilization, and microwave sintering. OSENSA’s optical temperature probes for microwave environments may be constructed from Teflon jacketing materials for maximum chemical and bio-compatibility, or from rugged stainless steel and high-temperature ceramics.

Fiber optic temperature sensors are inherently immune to microwave radiation and high-frequency electromagnetic radiation. Microwave environments where fiber optic temperature sensors are used include industrial microwave ovens for food processing and drying, microwave kilns for glass fusing, and paper, textile, or wood drying. Other applications include microwave sintering of ceramics and dental appliances, microwave sterilization, and microwave insecticidal treatment.

OSENSA develops custom fiber optic temperature probes that can be tailored for a variety of industrial microwave oven and microwave kiln applications. Osensa’s technology also permits short distance non-contact optical temperature measurement, and can measure temperatures in excess of 400°C.

Induction heaters and induction furnaces employ high-power alternating electromagnetic fields to rapidly heat electrically conducting objects. One example is barrel and in-mold induction heating for injection molding equipment. These heaters have operating frequencies between 5 to 100kHz and can consume 10 to 40kW of power. OSENSA’s industrial-grade fiber optic temperature sensors are ideally suited for these applications because of their natural immunity to intense electromagnetic energy, high reliability, and fast response time. OSENSA’s FTX series multi-channel temperature transmitter (signal conditioner) with 4-20mA analog outputs is easily integrated into injection molding process control equipment.

Research & Educational Temperature Sensing

research-man.jpgOSENSA supports research and development activities that require precise fiber optic temperature sensing solutions. OSENSA’s software and fiber optic probes can be customized and calibrated for a wide variety of laboratory and test applications.

Fiber optic temperature sensors are often selected for research applications because of their immunity to strong electromagnetic fields, nuclear and x-ray radiation. OSENSA’s fiber optic sensors are ideal for research applications because of their flexibility and ease of use. Simply install the OSENSAView software, and plug in the USB cable to start monitoring temperatures optically. OSENSA’s application support engineers will provide friendly assistance, and for more demanding applications, OSENSA can provide engineering consulting services. All projects are treated as confidential, and OSENSA regularly signs NDA (Non-Disclosure Agreements) to formalize this understanding.

OSENSA’s fiber optic temperature sensors are also great for student lab work and provide a unique educational activity for instructors of physics, chemistry, biology, electronics, and instrumentation. The advanced OSENSAView Pro software makes temperature logging, and calibration simple, and the low-cost, 100% polymer optical fiber probes will not break like standard glass optical fiber can. Plastic optical fiber temperature probes can be dropped on the floor, stepped on, and driven over, and they usually still work fine. In fact you can cut a plastic fiber optic temperature sensor in half, and piece the two halves back together and as long as there is enough light still travelling through each half, the probe will work.


OSENSA Innovations provides industry-leading fiber optic sensor design and component selection for OEM applications. OSENSA leverages existing commercial solutions wherever possible, often recognizing new ways to employ lower-cost technology in different applications. Our years of experience with fiber optic temperature, pressure, position, displacement, and CCD sensing allow us to employ the best possible solution for a given problem. Because we are not tied to any particular type of technology with any inherent limitations, we are free to explore and engineer the most cost effective solution to your application requirements.

OSENSA understands the need for continuous improvement and innovation in all aspects of business. Our goal is to provide the highest quality products and services that give our clients a protectable commercial lead. Our clients rely on our ability to deliver on what we say, and we offer a deep respect for, and appreciation of, the business they bring us. Please contact us today.