Infrared Thermography is the technique for producing a visible image of invisible infrared energy emitted by objects due to their thermal condition. The heat detector or focal plane array transforms the infrared radiation to electrical signals; the conversion of electrical signals to a visual image or thermogram is displayed in real time on the viewing monitor, typically the lighter the colour the hotter the object, conversely the darker the colour the cooler the object. The electronics housed within the camera permit for false colour images to be displayed making interpretation of thermal patterns more discernible.
All objects have a temperature above absolute zero (0 K) emit energy. Therefore all objects we encounter in our daily lives radiate thermal energy. Energy emitted within 3.0-14mm portion of the electromagnetic spectrum is within the thermal range that infrared cameras can define. Infrared energy is generated by the vibration and rotation of atoms and molecules. The higher the temperature of an object, the more the motion and hence the more energy emitted. Infrared energy behaves similarly to visible light; it travels through space at the speed of light, it can be reflected, refracted, absorbed and emitted. As humans, we primarily feel the thermal radiant energy from the sun or the radiant energy from a fire on our face. However, our eyes cannot detect subtle differences in thermal infrared energy emanating from the real world objects because our eyes are primarily sensitive to short-wave visible light within 0.4-0.7mm of the electromagnetic spectrum. Since our eyes are not sensitive to the reflective infrared (0.7-3.0mm), or thermal infrared energy (3.0-14mm) engineers have developed the focal plane array, this detector is sensitive to minute fluctuations to thermal radiation. Housed in cameras resembling a small handheld camcorder this allows our Thermographers to observe a previously invisibly world of heat, in the form of heat images called thermograms or thermographs.
The electromagnetic spectrum is the range of different electromagnetic radiations ordered by either frequency or wavelength (or both). Ranging from low-frequency (high wavelength) radio waves, through microwaves, infrared waves, light (the visible spectrum - red, orange, yellow, green, blue, indigo and violet) and continues through ultra violet waves, X-rays and to the very high frequency (short wavelength) gamma rays. In general, electromagnetic waves are set up by electrical and magnetic vibrations occurring in atoms. Travelling at the speed of light the electric and magnetic fields are propagated through time and space at right angles to each other and to the direction of propagation in discontinuous units called photons. The connection between the electromagnetic spectrum and radiation is best served with an example: when an metal bar is inadvertently heated the radiation is predominately emitted in the infrared, placing your hand over the object one can feel but not observe the effects of its warming. As the temperature of the object increases, the characteristics of the radiation change, the object begins to visually turn red and you can feel the heat at a greater distance. Because the object temperature increases then accordingly the wavelength decreases to enter into the visible portion of the electromagnetic spectrum, the result is likely to end in a catastrophic failure or fire if left un-checked.
Infrared thermography is being used by all major industries to help solve maintenance problems, improve safe working conditions, and control manufacturing costs, to detecting heat loss and construction flaws in buildings. When we are ill, usually the first thing we do is take our temperature. If our temperature is elevated it usually means something is wrong. Similarly, identifying and comparing component temperatures helps to identify many problems in their early stages of failure, often before they can be seen or found by any other condition monitoring method. A temperature difference, usually an abnormal hot spot, is typically associated with high electrical resistance or excessive friction. It is the job of the Thermographer to analyse, record and report these 'hot spots' to identify operational equipment that may potentially pose a hazard to plant integrity and operational efficiency. More importantly, identifying faulty equipment to minimise personnel risk. Since our cameras have a sensitivity of 0.5oC with a detectable temperature range from -20oC to 1200oC allows our Thermographers to detect hot or cold thermal anomalies before a lost-time incident occurs.
Infrared imaging is a non-intrusive, non-contact and cost effective inspection method utilising handheld portable equipment to capture energy losses or gains to help solve many costly maintenance problems. The system can be used while your plant is operational ensuring continual turnover of product and revenue, whilst indirectly assisting preventative maintenance procedures in locating faulty machinery for repair or replacement in readiness for scheduled shutdowns. Hence, thermography ensures a huge cost saving in labor costs, while ensuring machinery is fit for purpose from unscheduled shutdowns.
If you are responsible for the prevention of an unexpected breakdown or fire prevention - then this is for you. A infrared survey conducted by an insurance company revealed that loose connections from switchboards, switches, circuit breakers and cables resulted in 25% of all electrical equipment failures, locating high resistance hot-spot in a fraction of time than any other electrical inspection method. The identification of just one critical hot spot issue or a myriad of hot spots will underline the requirement for initiating a inspection program and help direct maintenance priorities before a outage occurs. Simply put the cost of one or regular thermal infrared inspection performed by a Geo Therm Ltd is likely to be paid for many times over by the elimination of just one unscheduled downtime incident or consequential fire damage.
Yes, measuring moving targets is one of the many benefits of using this non-invasive form of inspection. This is due to the quantity and sensitivity of the focal plane array detector within the camera. With over seventy four thousand detector elements on each array allowing more photons of energy from the instantaneous field of view to be recorded, and simultaneously resolving minute temperature differences in real time. This makes thermal infrared process monitoring extremely practical, particularly were high volume production lines are in force.
The greenish images relayed to the eye from night vision goggles are derived from the intensification of minute amounts of light found within the field of view, i.e. moonlight and starlight. Thermal imaging works by detecting heat energy being radiated by objects that require absolutely no light. Too much bright light can blind or wash-out night vision goggles whilst un-affecting thermal imaging cameras.
Inspecting all equipment in any plant is not always possible. Inspection frequencies varying from one piece of equipment or plant to the other, this invariably means establishing inspection routes in an efficient manner, while allowing enough flexibility so planned routes can evolve over time to better reflect actual needs. Working in-step with industry involves initial project planning to facilitate a smooth thermography program. This includes the identification of key players i.e. safety personnel, maintenance and engineering staff, the location of existing information, the prioritising of equipment and repair histories and equipment criticality to allow ourselves to move forward toward the results you are looking for. At Geo Therm Ltd we pride ourselves at working in-step with our clients, offering invaluable assistance in helping to define their thermographic and infrared equipment needs, making recommendations whenever necessary to improve equipment reliability and our clients standing in the market place.
The facilities inspection report is the final step in the infrared process. Our report includes all parts of the inspection process, from exceptional quality survey design in preparing the survey, to asking the questions and collecting the answers in the form of data that is analyzed, compiled and presented to you in a meaningful and easy-to-understand format. Your company will receive two printed colour reports, identifying thermal or ulta-sound anomalies, the location and a brief description detailing each issue raised and level of importance for repair. Included with the hardcopies is a report copy on compact disc. Subject to the work scope, our reports have a normal turnaround period of five to seven working days following the end of the inspection
Additional benefits from implementing a thermography program can trigger reductions in insurance premiums, while surveys scheduled prior or post shutdowns can actively encourage quality control measures verifying and evaluating repaired work, or procurement of new plant and building installations. Indentifying the location of heat loss and air leaks from buildings with no or little insulation saving money on heating bills. Thermography can also assist in-house concerns at pursuing environmental quality goals to limit levels of carbon dioxide emissions through the burning of fossil fuels, in-effect saving more money on heating expenditure. It is now law to have an air leakage test of all new commercial or industrial building before it is commissioned, Building Regulations, Part L. Companies with a well-developed infrared program combined with air leakage testing are finding returns on their investments in excess of 30:1; instigating an infrared program and air leakage test will quickly pay for itself and then begin adding to the profit margin to your company.
This is quite true, although the answer can be as complex as the environment. Since the Sun is the prime cause of weather, differential heating upon the Earth's surfaces will directly influence solar loading on those areas being surveyed. The amount of this heating varies a large amount depending on the angle of the surface, the colour of the surface, and the shading and reflection from adjacent surfaces. The differences in solar loading directly influences surface air pressures and hence size, shape and orientation of winds, in addition to precipitation quantities. These varied meteorological effects close to the intended target and factors including severity criteria guidelines, including direct or indirect measurement, equipment type and load all influence the Thermographers evaluation of any issues that can be encountered. Such is our commitment and flexibility that even at short notice we can tailor our operations to suit operational and environmental conditions, thereby minimize waiting time to achieve the best results possible.
The use of thermal infrared cameras and Ultra-probes offer little risk to the surveyor or to those helping with the survey and or others within the vicinity, since the inspections are non-contact and passively detect heat or ultrasound from the target object. This means that it is safe to view and or listen to energized electrical systems or moving/rotating parts without physically touching or dismantling them. Due to legality and safety constraints our personnel are prohibited to open or physically remove protective guards. Both inspection systems are handheld, portable and lightweight with different lens attachments to optimize thermal hot-spot detection and improvement in field of view, or adding sound concentrator cones or insulated contact probes to focus distant or nearby sound emissions for pin-point accuracy. Placing mirrors during infrared surveys further limit operational risks, as difficult angles between the surveyor and target objects are easily obtainable. Using the above methods also means that the actual thermal characteristics and sound patterns are unaffected.
NIOSH (National Institute for Occupational Safety and Health) definition of an arc flash as: “An arc flash is the sudden release of electrical energy through the air when a high–voltage gap exists and there is a breakdown between conductors.” The causes of arc flash are many, ranging from rodents, to insulation breakdown, to dust and contaminants. However, the predominant causes are human initiated and occur when the panel covers are not in place, or during panel removal or reapplication or when opening or closing equipment doors. In less than 1/1000th of a second, the centre of an arc flash can reach temperatures of 35,000℉ / 19427℃ which is nearly four times the temperature of the surface of the sun (roughly 9,000℉ / 4982℃). This rapid heating causes copper bus bars to turn from solid to a plasma state in a fraction of a second, expanding 67,000 times. At that rate, a pea sized piece of copper will expand to the size of a railway carriage. This instantaneous expansion of machine parts and the surrounding air creates an “arc blast” carrying a pressure wave of thousands of pounds of force, super-heated gases and molten shrapnel. Not surprisingly victims of arc blast trauma report horrific burns, shrapnel wounds, damaged internal organs, hearing loss, blindness and lung damage. The retro-fitting of infrared inspection windows into your electrical systems will allow safe visual and or infrared inspections, and forever prevent the harmful effects when inspecting live electrical equipment.
Ultra-sound is acoustic energy in the form of sound waves, having a frequency above that of the human hearing range. We (humans) hear sound between 20 - 20,000 Hz with an average threshold of 16.5 kHz, most ultra-sonic detectors detecting range start at 20 kHz and work upward to as high as 100 kHz. The lengths of low frequency sound waves in the audible range are approximately 1.9 cm up to 17 m, whereas Ultra-sound wavelengths are much shorter at 0.3 cm up to 1.6 cm long. Hence Ultra-sound wavelengths are magnitudes smaller and as a result they are typically more directional in transmission. This makes the Ultra-sound method the ideal means to locate and isolate electrical and mechanical problems in noisy environments, hence our Ultra-sound surveyors can accurately identify unheard and unseen PD and mechaical anomalies before operations are disrupted.
Both Thermographic and Ultra-sound systems have their merits. When used together they are mutually beneficial, able to tackle more PM and Classification requirement issues albeit from a different perspective, i.e. visualizing and radio-metrically measuring energy in the form of infrared energy (heat), or listening to and analysing sound spectra to locate numerous mechanical, electrical and process related anomalies, bot inspection methods are used to maintain asset availability, reduce maintenance overheads and improve safety conditions. No one technology can cover everything, the recommendation is to incorporate as many cost effective condition monitoring technologies that is feasibly possible into your inspection procedures to ensure continued operation.
Partial Discharge (PD) is the early stages of electrical insulation breakdown under high voltage. It is categorised into three forms: 1. arcing, 2. tracking and 3. corona. If undetected PD has the ability to seriously damage equipment. Often PD is present well in advance of insulation failures, continuous monitoring provides the clear evidence that the asset is deteriorating in a way that is likely to lead to failure. Once initiated PD causes a progressive breakdown of the insulating material which can result into a flashover incident and potential catastrophic failure. Once PD activity is present, even if it is intermittent, damage will ALWAYS increase over time. The process of deterioration will propagate and develop until the insulation is unable to withstand the electrical stress, leading to flashover and downtime event.
PD is measured acoustically using either a handheld Ultra-sound probe or fixed installation units that filter and isolate those audio frequencies that are not associated with PD allowing any true PD audio signatures to be heard.Partial Discharges are small electrical sparks that occur within the insulation due to manufacturing defects and voids within the insulation, or initiated by dirt or other surface defect. Corona, arcing and tracking are the main concerns in electrical PD one of the by-product of PD is Ozone. When Ozone and humidity combine Nitric acid is formed that further deteriorates insulation properities. Each PD emission has a characteristic waveform and sound that is a common diagnostic of that condition. PD can be continuously monitored by retro-fitting magnetic listening nodes to the switchboard panel doors or transformer housings, these nodes are daisy chained together providing multiple real-time recording points, (this system can be remotely accessed anywhere in the world) or surveyed independently using a handheld Ultra-probe device. If PD is found and allowed to continue it will eventually erode the insulation and result in a complete breakdown and failure of the component causing unplanned power outages, loss of production, equipment damage and injury. Data obtained through the use of PD hand held probe and or continuously monitored will provide critical information regarding the quality of insulation and its impact on system health. The advantages are clear and concise: 1. No disruption to production. 2. Data collected while switchgear, transformers and cables are under normal working loads. 3. Early identification of developing faults. 4. Planned maintenance interventions. 5. Targeted maintenance. 6. Improved reliability.
Yes they can! The Ultra-sound probe has an in-built modulating system that tunes out unwanted background noise and tunes into specific frequencies to pinpoint the high frequency emission source, this process is called heterodyning. The technology is suitable for almost all industrial environments needing frequent spot checks for PM needs. The high frequency, short wave characteristic of Ultra-sound enables users to accurately pinpoint the location of a gaseous or liquid leak or of a particular mechanical or electrical sound. Typically when a Ultra-sound is present there is a shift in sound level and spectra signal amplitude and frequency. In electrical systems operating in good condition there is generally a nice recognizable background hum, whereas an erratic stop starts are indicative to Partial Discharge associated with arcing, or a continuous buzzing noise indicating corona, or combined with a subtle popping noise denoting destructive corona. A less intense and infrequent arcing noise indicates tracking. These characteristic noises are inaudible to the human ear, until the systems is about to fail.
Like the thermographic surveys the ultra-probe is a non-invasive handheld instrument allowing information to be gathered from a safe distance, however, unlike thermography a line of sight is not necessary to detect an anomaly since the handheld Ultra-sound probe can be aimed along a air-gap, through a air vent or passed along a poorly fitted door seal or aimed through a retro-fitted sound port like the: IRISS VP-12-US. By using a sweeping side to side and up and down motion it is possible to zero-in and pick out any high pitched Ultra-sounds. The Ultra-sound probe works on all voltages, low, medium and high, with the inaudible signal being electronically processed or heterodyned - a form of modulating turning the inaudible into audible sound. The processed harmonics are listened to by wearing a pair of ear phones and the spectra signal viewed from an inbuilt spectrograph located at the pistol grip end of the probe. Both the sound and waveform spectra aid diagnoses to determine if the asset has for instance mechanical issues such as bearing friction/wear issues or electrical PD occurrence in transformers or switchboards or valve systems are passing and or steam trap mal-functioning in compressed air or hydrocarbon piping systems. Allowing Geo Therm Ltd to survey your companys electrical, mechaical and process related equipment will likely save you many thousands with the first inspection.
The fixed PD condition monitoring system uses magnetic nodes and listening devices that are configured to suit your application, these devices are daisy chained together and combined with a Human Machine Interface (HMI) sited at asset location for analysis. The system is retro-fitted to your equipment without shutting equipment down, so no loss of productivity. This system allows prompt decision making when issues are raised at source, or we can configure the system to alert management via texts or email messages who are based further afield, furthermore the system can be remotely accessed via the Web anywhere in the world. By using this PD condition monitoring system the vital switchgear and transformers assets will: 1. Remove the limitations inherent with time based spot checks. 2. Removes the possibility of both false-positive and false-negative results inherent with hand held test equipment and time based spot testing. 3. Will identify a problem at its earliest stage of development. 4. Provide constant information on the growth rate and severity of a problem. The fixed based PD condition monitoring system also accounts for variables such as: Seasonal, atmospheric, operational load conditions, equipment age and equipment type, none of which can be achieved using handheld instruments. Moreover, the system is in continuous operation providing real time indication of the switchgear or transformer condition, and able to inform you of potential problems prior to entering the switchgear/transformer room, reduce unnecessary maintenance, providing surgically target maintenance while extending maintenance time intervals with confidence.
Sound waves require a medium such as a solid, gas or liquid in which to travel. In air at sea level and at room temperature sound waves travel at the speed of 340 m/sec. In water the speed of sound is approximately 1500 m/sec and within metals an average of 6000 m/sec, (almost 20 times more than in air). Sound is produced by a vibrating body about an equilibrium position and propagated as longitudinal waves consisting of alternate compression and rarefaction zones along the direction of propagation at a constant velocity. Sound can be received or detected in two ways: passively through the air or via contact through solid surfaces. Ultra-sound instruments translate these high frequency sounds down to the audible range where they can be heard through headphones and associated spectra viewed as intensity levels (decibels) on a display panel. Some ultrasound instruments log test information, while others have onboard sound recording along with data logging capability. The ability to view sound levels while simultaneously listening to sound quality enhances the monitoring effectiveness – allowing our surveyors to quickly identify changes in equipment condition (e.g., in bearings, leaks and electrical PD) that occur from increases in decibel levels and changes in sound quality as they collect data along the inspection route. Additionally, Ultra-sound allows our surveyors to pick up fault conditions that can’t always be detected by vibration or seen by infrared technology, such as equipment enclosed in interloacked switchgear and transformer housings.
Insulation materials used in electrical equipment may contain small microscopic voids or cracks, when the system under scrutiny is energised, these imperfections charge-up and discharge with the characteristic 60 or 50 Hz cycle, like small capacitors. Since air breaks down more readily then the insulation material it produces small arcs and a Partial Discharge occurs. These arcs produce heat, light and sound and electromagnetic radiation, with only the electromagnetic radiation being detected externally via high frequency Ultra-sound probes set within the 40 kHz range. As a consequence of the discharge, erosion occurs within the imperfections, as the imperfections get bigger the discharge energy dissipated with each discharge increases in magnitude to eventually coat the imperfections with carbon, making the imperfections conductive. Under normal working voltages and particularly following transient over-voltages (for example, by switching operations) the system fails and a flash over occurs following the path of least resistance, that is, via the carbonised imperfections within the insulation.
Yes and No. The need for either inspection method is dependent upon your application. Both inspection methods have their own limitations and advantages. However, when used together they are mutually beneficial, able to tackle more PM / Classification issues albeit from a different perspective, i.e. visualizing and radio-metrically measuring energy in the form of infrared energy (heat) generated by friction and or electrical high resistance; whereas Ultra-sound is geared toward listening to and incipient sound and analysing sound spectra to locate inaudible anomalies. Both inspection methods are used to obtain valuable information to manage your asset availability, reduce maintenance overheads, improve safety conditions, comply with PM requirements, Classification and insurance prerequisites. No one technology can cover everything. The recommendation is to incorporate as many cost effective technologies as possible into your maintenance regime, to ensure your equipment is being monitored and maintained in a safe manner.