Infrared

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

September 4

2005 Brought to you by – Ritesh Bhusari

Infrared application in Mechanical Industry

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

ABSTRACT: This exciting seminar is designed for anyone interested in making the most of a predictive maintenance program. The peculiarities of infrared photography lie in the ability of the film to record what the eye cannot see (permitting, for instance, photography in the dark); in the fact that many materials reflect and transmit infrared radiation in a different manner than visible radiation (light); in the ability of infrared radiation to penetrate certain kinds of haze in the air so that photographs can be taken of distant objects that cannot be seen or photographed on normal films; and in the ability to photograph hot objects by the long-wavelength radiation that they emit. This can be useful in a various applications such as monitoring the condition of electrical machinery and checking the efficiency of the building insulation. A typical system will display an image in different colours, each colour band has its specific meaning, which indicates different temperatures. In this article I would like to present an overview of infrared imaging and thermography.There is no other technology that can compare to the versatility of infrared Thermography with its immediate playback. Whether you are in management or in a technical position, this seminar will help you understand the immense role Infrared Thermography can play important role in your Maintenance program. Reduce downtime, increasing profits, predict failure before they occur. A properly designed and implemented infrared program can increase employee safety as well as equipment reliability.

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

INTRODUCTION:WHAT IS INFRARED? Sir William Herschel, an astronomer, discovered infrared in 1800. He built his own telescopes and was therefore very familiar with lenses and mirrors. Knowing that sunlight was made up of all the colors of the spectrum, and that it was also a source of heat, Herschel wanted to find out which color(s) were responsible for heating objects. He devised an experiment using a prism, paperboard, and thermometers with blackened bulbs where he measured the temperatures of the different colors. Herschel observed an increase in temperature as he moved the thermometer from violet to red in the rainbow created by sunlight passing through the prism. He found that the hottest temperature was actually beyond red light. The radiation causing this heating was not visible. Herschel termed this invisible radiation "calorific rays". Today, we know it as infrared. He measured radiation effects from fires, candles, and stoves, and deduced the similarity of light and heat. Today, devices can be designed to detect, amplify, and display radiation from the visible or infrared portions of the spectrum.

What is Infrared Radiation? The light we see with our eyes is really a very small portion of what is called the "Electromagnetic Spectrum." Infrared radiation is electromagnetic radiation whose wavelengths are greater than those of visible light but shorter than that of microwaves. The Electromagnetic Spectrum includes all types of radiation - from the X-

rays used at hospitals, to radio waves used for communication, and even the microwaves you cook food with.

Radiation in the Electromagnetic Spectrum is often categorized by wavelength. Short wavelength radiation is of the highest energy and can be very dangerous - Gamma,

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

X-rays and ultraviolet are examples of short wavelength radiation. Longer wavelength radiation is of lower energy and is usually less harmful - examples include radio, Microwaves and infrared. A rainbow shows the optical (visible) part of the Electromagnetic Spectrum and infrared (if you could see it) would be located just beyond the red side of the rainbow.

Although infrared radiation is not visible, humans can sense it - as heat. Put your hand next to a hot oven if you want to experience infrared radiation "first-hand!

THE ATMOSPHERE — A FILTER: Just as sunlight is scattered by smoke, the atmosphere reduces Infrared energy by absorption and scattering. However, there are several "windows" in the spectrum where this effect is minimized. Selection of detectors that operate in these windows in the NEAR INFRARED (NIR), MIDDLE INFRARED (MIR), and FAR INFRARED (FIR) permit practical operation.

HOW HOT IS IT ? It is helpful to understand the relationship between wavelength and object temperature. Photographers refer to lighting effects on film by "effective color temperature." Objects heated to temperatures which radiate at short wavelengths will become visible; for example a light bulb filament. As objects become cooler, the wavelength becomes longer and the object visible darkens. Objects at normal temperatures radiate in the FIR portion of the spectrum. A hot soldering iron, although not visible, would be considered NIR. A hot coal on a fire would have its peak radiation level in the MIR portion of the spectrum. Thus, selection of systems is related to the kind of detection required.

NEAR INFRARED (NIR): Since this portion of the spectrum is close to the visible region, objects that are quite hot will most easily be detected with equipment operating in this region.

MIDDLE INFRARED (MIR): This portion of the spectrum includes peak radiation given off by fire, and also includes a substantial portion of solar energy reflected from other objects.

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

FAR INFRARED (FIR): The relatively cooler temperatures of most objects on a normal day radiate peak energy in this part of the spectrum. For high- resolution detection, it is advantageous to operate in this region.

Why measure temperature? Finding a problem with an infrared camera is sometimes not enough. In fact, an infrared camera image alone without accurate temperature measurements says very little about the condition of an electrical connection or worn mechanical part. Many electrical targets are operating properly at temperatures that are significantly above ambient. An infrared image without measurement can be misleading because it may visually suggest a problem that does not exist. Infrared cameras that incorporate temperature measurement allow predictive maintenance professionals to make well-informed judgments about the operating condition of electrical and mechanical targets. Temperature measurements can be compared with historical operating temperatures, or with infrared readings of similar equipment at the same time, to determine if a significant temperature rise will compromise component reliability or plant safety.

How Infrared Camera is used ? An infrared camera is a non-contact device that detects infrared energy (heat) and converts it into an electronic signal, which is then processed to produce a thermal image on a video monitor and perform temperature calculations. Heat sensed by an infrared camera can be very precisely quantified, or measured, allowing you to not only monitor thermal performance, but also identify and evaluate the relative severity of heatrelated problems. Recent innovations, particularly detector technology, the incorporation of built-in visual imaging, automatic functionality, and infrared software development,deliver.

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

Every object whose surface temperature is above absolute zero (-273 °C) radiates energy at a wavelength corresponding to its surface temperature. Utilizing our highly sensitive infrared cameras, it is possible to convert this radiated energy into a thermal image of the object being surveyed. All of our thermal images feature extremely accurate embedded temperature measurement systems for fast, precise quantitative documentation of the object's thermal characteristics.

Normal wear, vibration, chemical contamination, corrosion, fatigue, and faulty assembly or installation may lower the conductivity and increase the resistance level of a connection or component. This increase in resistance will cause an increase in the temperature of the connection or component. Excessive heat can be readily noted and the temperature rise measured by the infrared camera. Increased temperatures indicate potential trouble spots, which could lead to failure of the component. An Infrared Electrical Equipment Inspection is performed while the electrical system is under normal load. This non-contact, non-destructive technique causes no disruption to the normal operating routine of the system being inspected. .

violet

RED

Sensor Technology : Uncooled Thermal Sensor Technology : A paradigm shift has occurred in the commercial infrared camera industry as a result of classified military thermal sensor development in the 1980’s. In the past most high performance infrared cameras used in commerce had photon-detection sensors that needed to be cooled to liquid nitrogen temperature (77K). Cryogenic coolers were used to cool the detectors requiring about 10 minutes turn-on time to achieve this very low temperature. New high performance cameras use thermal sensors that eliminate the need for cryo-coolers. Their turn-on time is 15 seconds or less. Cryo-coolers are expensive and have wear-out issues. The elimination of the cryo-cooler and advances in electronics has made the cameras smaller, more reliable and less expensive.

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

Types of sensors : 1) Thermal Sensing technology : The principle of a thermal infrared sensor is shown below. A tiny thin plate (which I call a “platelet”) is made on a silicon wafer in a silicon foundry by a micromachining process. The platelet is typically 50 m (microns) square by 0.5 m thick. Even smaller sizes are under development. Long thin support legs and a vacuum environment thermally isolates it from the surrounding environment. Small thermal radiation from the target focused onto the platelet heats it. The higher the target temperature, the greater the focused radiation is and therefore the higher the platelet temperature. The temperature of the platelet and therefore the intensity of the radiation can be measured by the change in resistance of an electrical resistor deposited on the platelet the microbolometer sensor.

It can be measured by a thermocouple with the hot junction on the platelet and the reference junction on the substrate the thermoelectric sensor. Or it can be measured by an electrical capacitance effect the pyroelectric sensor. The microbolometer and thermoelectric sensors were developed by Honeywell and are effectively used in Infrared cameras. A) Microbolometer sensors : Individual sensor elements use the change in electrical resistance of a vanadium oxides (Vox) resistor deposited onto the tiny “platelets” fabricated by silicon micromachining in a silicon foundry. Incoming target radiation heats the VOx causing a change in electrical resistance, which is readout by measuring the resulting change in current. 80,000 and more sensors can be fabricated together into a two-dimensional array. The structure can be dimensioned to operate at 30 Hertz. That is, the thermal conductance of the isolating legs can be adjusted to match the time-constant for 30-hertz operation. An example of a microbolometer element is pictured below. It consists of a two-layer structure. An interconnecting readout circuitry is applied to the silicon process wafer and then the microbolometer structure is built on top of the readout circuitry. First a pattern of islands wavelength thick are deposited on the readout circuitry.

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

The islands are made of a material that can be selectively etched away later to form a bridge structure. Three layers silicon nitride, vanadium oxide, and silicon nitride are deposited over the sacrificial islands. The sacrificial islands are then etched away leaving the thermally isolated bridge structure of vanadium oxide. A photo of an early Honeywell microbolometer element is shown in the picture below followed by a photo of one corner of a 320 by 240 microbolometer array.

Most of today’s camera manufacturers use the 320 by 240 microbolometer array. However there is an excellent alternative for many commercial applications the 160 by 120 array. The smaller array and its resulting camera can be produced at a much lower cost. Far more arrays can be produced on a single wafer and the yield is higher for the smaller array. In addition, one of the most expensive components of an infrared camera is the lens and its cost is proportional to the array size. The only advantage of the larger array is field of view (FOV). With the same focal length lens and the same detector size, a camera with 320 by 240 or 160 by 120 will have identical spatial resolution. But the target size for a fixed distance between the camera and target will be twice as large in both dimensions for the camera with the larger array. For many commercial applications the cost savings of the smaller array size over shadows the advantage of a larger FOV.

B) Thermoelectric sensors : Individual sensor elements use thermocouples to measure temperature change of the tiny platelet. The platelet, typically 50-micron square by 0.5-micron thick, is fabricated by silicon micro machining in a silicon foundry similar to, but easier than, the microbolometer. Up to five series-connected thermocouples are deposited on each platelet. They produce a small voltage caused by the target radiation heating the platelet. 120 sensing elements are fabricated together into a linear array. We have exclusively used this Honeywell array for the IR Snapshot camera. Moving the sensor array in the focal plane of the camera lens produces a twodimensional image. The resulting thermal image consists of 14,400 pixels (120 by 120). A cross section diagram of a thermoelectric sensor is pictured below.

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

Silicon nitride is deposited on the silicon wafer to produce a thermally isolating platelet pattern. A well pit is selectively etched out of the silicon wafer under the platelet. Dissimilar metals A and B are deposited on the platelet structure. Electrical contacts are added along side of the sensor for external connection. A photo of a partial early Honeywell thermoelectric sensor array is shown in the picture below. Three detector elements are pictured. Each element has three thermocouples in series. Because this array is linear, all the electrical connections can be put off to the side permitting a high fill factor.

2) Photon detector technology : Photon detectors have been widely used for visible imaging for some time. The semiconductors used for cameras working at visible wavelengths do not have small enough band-gaps to low-energy infrared photons, and small band-gap semiconductors such as Mercury cadmium Telluride (HgCdTe) are needed. Small band-gaps means that, at room temprature, there is significant noise from thermally generated charge carriers, So these detectors have to be cooled to very low temperatures(<100 K). This requires supply of liguid nitrogen, or closed-cycle refrigerators

Advantages : 1) Portable. 2) Instant Results. 3) Doesn't require the use of chemicals to visualize films as in normal cameras. 4) IR is not harmful to skin. 5) Ease of presentation and visualization. 6) Effective and Efficient. 7) This can serve your inspection needs at night or in broad daylight.

Disadvantages : 1) Resolution is lost with distance. 2) Expensive. 3) Less expensive digital cameras uses cryo-coolers for cooling which are expensive.

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

Industrial Application : 1 } Building Envelope The primary diagnostic procedure for determining the thermal performance of a building envelope is infrared thermography. It can be used to identify heating and cooling loss due to poor construction, missing or inadequate insulation and moisture intrusion. Correcting the defects plays a significant role in increasing building efficiency and structural integrity. Conductive Losses

Problems identified as conductive losses are: missing insulation, improperly installed or compressed insulation, shrinkage or settling of various insulating materials; excessive thermal bridging in joints between walls and the top and bottom plates. Air Leakage

Air leakage is the passage of air through a building envelope, wall, window, joint, etc. Leakage to the interior is referred to as infiltration and leakage to the exterior is referred to as exfiltration. 2 } Food Industries The food industry must maintain tight control of food temperatures during the transportation of perishable food materials, during preparation and processing, and all the way through storage in wholesale and retail environments. 3} Manufacturing Infrared cameras and accessories meet and exceed the most stringent monitoring and inspection requirements in the demanding manufacturing environment. IR thermography has been used for decades by predictive/preventive maintenance professionals and process and quality assurance engineers to solve the tough problems as well as day-to-day maintenance challenges. 4 } R&D/Testing As the global leader in infrared cameras, the most advanced infrared temperature measurement systems for applications that demand superior thermal uniformity and/or controlled heat dissipation: micro-electronics, paper processing, automotive, plastics, injection molding, consumer appliance design, telecommunications, target heat signatures, mechanical testing, R&D and much more. IR cameras capture and record thermal distribution in real time helping engineers visualize and quantify heat patterns in the devices they create and events they monitor. 5 } Steel Infrared cameras save money and help produce quality steel products and save time and money by enabling routine thermal surveys of ladles, torpedo cars, and other refractory equipment and/or components, as well as the large, high horsepower motors running the finishing mill stands. Unscheduled downtime for only one of these motors can result in production losses that are estimated at $6,000 per minute. Infrared cameras are designed to provide fast, reliable, accurate monitoring and control. They enable steel mills to routinely achieve and verify temperature.

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

6 } Mechanical Systems We have a few examples of thermography for mechanical systems. The first two thermograms, P) and Q) below show electric motors at 30C (54F) and 40C (72F) above ambient, respectively. Thermogram R) shows a motor coil under test. The camera operator is looking for shorts, which will show up as temperature anomalies. Thermogram S) is a coupling for a high horse power motor and is 6C (10F) below the motor bearing temperature and 12C (20F) below the machine bearing temperature. It is well within its normal operating temperature.

P) Electric motor

Q) Electric Motor

R) Coil Test

S) Coupler

Thermogram T) is an oil field natural gas compressor where the cylinder head in the lower left of the picture shows signs of a valve problem. Not counting the bolt head parts of the images, this cylinder head shows a 25C (45F) temperature gradient. This gradient was felt to be excessive and it resulted in a tear down and servicing of the compressor. Thermogram U) is an image of a rotating one-foot diameter 3 feet long pinion gear that drives a 50-foot diameter drum in a molybdenum mining operation. By monitoring the lengthwise temperature gradient, the technician could monitor the gear alignment and its life expectancy. Thermograms V) and W) are images of pipe with band heaters. V) shows the heaters on and functioning and W) shows them not working.

T) Compressor

U) Pinion Gear

V) Band Heater

W) Band Heater

7 } Glass Manufacturing Since the nature of the glass manufacturing process is thermal, the quality of the glass manufactured is dependent on obtaining accurate temperature readings of various elements such as the glass mold, “gob”, steel conveyor belt and the furnace. Using easily deployable infrared equipment to monitor these temperatures as well as preventing electrical and mechanical failure by carrying out traditional predictive maintenance with such equipment can result in a higher quality product and minimize costs by averting failures. 8 } Condition Monitoring: Industrial pumps are known to work continuously for many hours. If a pump stops working or starts to wear, this can cost a factory much needed time. Using an

w.

A B B Y Y.c

om

Y

F T ra n sf o

A B B Y Y.c

bu to re he C

lic

k

he k lic C w.

om

w

w

w

w

rm

y

ABB

PD

re

to

Y

2.0

2.0

bu

y

rm

er

Y

F T ra n sf o

ABB

PD

er

Y

IR camera to monitor the temperature of these type pumps, a maintenance worker can spot troubled pumps before the failure and address with little or no down time - saving you time and money. 9 } Predictive Maintenance: Monitor temperatures of bearings and other moving components. Friction is a machine’s nightmare, and an engineer or technician would do anything to avoid it. As bearings wear with time, they begin to slow machinery and create unnecessary heat. Monitoring changes over time can help predict when maintenance needs to be performed. Neither too soon, nor too late. Saving the costs of unnecessary maintenance. 10 } Roofing Inspection: Infrared inspection of this industrial roof reveals water saturation due to leaks or condensation under the roof membrane. The heat generated by sunlight dissipates much slower where moisture saturated insulation exists. As a result, the moisture soaked roof areas appear quite clearly when performing an infrared scan

Conclusion : So, finally we conclude that the Infrared is very effective in analysis of the objects having some specific temperature and analysis will be an easy task by using thermographs shown by Infrared camera. The infrared camera industry has experienced huge changes in the last 5 to 10 years and we can expect more changes in the future. We will find more uses for the technology and camera costs will continue to drop. The cameras will also have higher performance and be simpler to operate.

References : 1 ) www.infrared.com 2 ) www.infraredsolutions.com 3) www.flirthermography.com 4) A textbook on optics (Fourth Edition) By Eugene Hecht

v THANKING YOU

w.

A B B Y Y.c

om