A proximity detector (sensor) is a detection device that can trigger an alarm when an intruder approaches it. In the proximity detector, there is usually a high-frequency LC oscillating circuit, and the LC loop of the oscillating circuit is connected with external metal parts through wires. When the human body approaches, the resonant frequency of LC circuit will change due to electromagnetic coupling in space, which will lead to the change of oscillation frequency. The detection circuit of the detector can recognize this frequency change and send out a warning signal.
Proximity detectors are more suitable for indoor use, such as protecting some special objects such as desks, filing cabinets, safes, etc., and can also be used to protect doors and windows. Usually, the protected object is metal, which can actually form a part of the protection circuit, so as long as someone tries to destroy the system, an alarm will be triggered immediately.
The main advantages of proximity detection system are versatility and versatility. It can be used to protect almost any object from interference from a few meters away. Once someone approaches or touches jewelry boxes, filing cabinets, doors and windows for theft, it will trigger an alarm, but the normal business work nearby can be carried out as usual.
When approaching the circuit design of the detector, we need to pay attention to several key technical points: ① the selection of frequency, the detection sensitivity is low when the frequency is too low, and the false alarm is easy to appear when the frequency is too high, so we should try to avoid the radio frequency point; (2) The power consumption is low, and the proximity detector is sometimes made into a small portable alarm, which needs battery power supply. Using battery power supply is also conducive to improving the anti-interference ability of the circuit and reducing false alarms; (3) The resonance frequency of 3)LC oscillator circuit is also influenced by external environmental factors (such as temperature and humidity), so it is meaningless to detect the slow change of oscillation frequency, but the sudden change of oscillation frequency should be detected, and only the "sudden change" of oscillation frequency is related to possible cheating.
Motion/vibration detector
A sensor that can detect the position of a moving fixed object is called a motion detector. In fact, movement is everywhere, the earth is turning, and everything on the earth is "moving". What we want to detect here is actually relative motion, such as objects placed on the desktop being removed from the desktop, parked vehicles being started or moved, and so on.
Mobile detection equipment is most suitable for the protection of valuable and confidential special items such as filing cabinets and safes, and is also suitable for combining with other systems to prevent thieves from entering through walls. The validity of mobile detector is closely related to the correctness of its application. It is often used to protect some special objects and people in protected areas.
In order to detect the movement of the protected object, it is necessary to find out the physical quantity changes that can be produced by the movement. At present, there are at least: mechanical method, optical method, electromagnetic method and vibration detection method.
Active optical intrusion detector
Light travels in a straight line, so it is called "light". If the propagation path of light is blocked, the light will be interrupted and cannot continue to spread. Active optical intrusion detector uses the linear propagation characteristics of light to detect intrusion, which consists of optical transmitter and optical receiver. The transmitter and receiver are installed separately, and an optical warning line is formed between the transceivers. When the intruder crosses the warning line, the light is blocked, the receiver loses its illumination and sends out an alarm signal.
Generally, infrared radiation outside the visible spectrum is selected as the light source of the transmitter, so that intruders cannot detect the existence of warning lights. In order to avoid the interference of natural sunlight, two technical measures are usually taken:
① Add a color filter on the light receiving window of the receiver to filter other light;
(2) Modulating the amplitude (intensity) of transmitter light, specifically: using infrared light-emitting diode as the light-emitting device of transmitter light source, and modulating the voltage or current of transmitter light source power supply with modulation signal with frequency of several KHz, so that the intensity of light emitted by transmitter also changes according to the law of modulation signal. In the receiver, the infrared receiving diode is used to receive the optical signal, and the signal is amplified by an amplifier with a tuning loop, so that the interference of other signals with different frequencies in the modulation signal can be filtered out. Sunlight is a stable light without any modulation, and the signal generated on the receiving diode is naturally filtered out and there is no response.
passive infrared detector
Using the physical principle of "blackbody radiation", as long as the temperature of an object is higher than absolute zero, it will continuously radiate light around, and the wavelength of the radiated light is related to the temperature of the object. At normal body temperature, the human body can emit far infrared rays, which are invisible to the naked eye, but infrared sensors can detect them, so intruders can be found. The core component of the detector is pyroelectric infrared detection element, which is equipped with a "Fresnel" lens made of transparent plastic, so it can monitor a certain spatial range, with convenient installation, high sensitivity, no need for auxiliary light source, low power consumption and relatively low cost. It is a popular electronic security product component now.
As long as the temperature of all objects in nature is higher than the absolute temperature (-273℃), molecules and atoms move irregularly, and their surfaces constantly radiate infrared rays. Infrared is an electromagnetic wave with a wavelength range of 0.78 ~ 1000um, which is invisible to human eyes. Infrared imaging equipment is a device to detect invisible infrared rays radiated from the surface of this object. It reflects the infrared radiation field on the surface of the object, that is, the temperature field.
Note: Infrared imaging equipment can only reflect the temperature field on the surface of an object.
For power equipment, the basic principle of infrared detection and fault diagnosis is to obtain the thermal state characteristics of the equipment by detecting the infrared radiation signal on the surface of the equipment to be diagnosed, and to diagnose and judge whether there is a fault, fault attribute, occurrence position and severity of the equipment according to this thermal state and appropriate criteria.
In order to deeply understand the infrared diagnosis principle of power equipment faults and better detect equipment faults, the relationship and law between the thermal state of power equipment and the infrared radiation signal generated by it, the influencing factors and the working principle of DL500E will be discussed.
I. Infrared radiation emission and its laws
(A) the infrared radiation law of blackbody
The so-called blackbody is simply an object whose absorption rate of incident radiation of all wavelengths is equal to 1 in any case, that is to say, it is completely absorbed. Obviously, because any object actually exists in nature has certain reflection on incident radiation with different wavelengths (the absorption rate is not equal to 1), the black body is just an idealized object model abstracted by people. The basic law of blackbody thermal radiation is the basis of infrared research and application, which reveals the quantitative relationship between infrared thermal radiation emitted by blackbody and temperature and wavelength.
Next, I will focus on three basic laws.
1. Planck's radiation law-the spectral distribution law of radiation
For a blackbody with an absolute temperature of T(K), in the unit wavelength range near the wavelength λ, the radiation power (spectral irradiance for short) Mλb (T) emitted by the unit surface area to the whole hemisphere space satisfies the following relationship with the wavelength λ and the temperature t:
mλb(T)= c 1λ-5[EXP(C2/λT)- 1]- 1
Where C 1- the first radiation constant, c1= 2π hc2 = 3.7415×108 w m-2 um4.
C2—— the second radiation constant, C2 = HC/k =1.43879×104um k.
Planck's radiation law is the basis of all quantitative calculation of infrared radiation, and the introduction is abstract, so I won't elaborate on it here. 2. Variation of radiation power with temperature-Stephen Boltzmann's law
Stephen Boltzmann's law describes the variation of the total radiation power Mb(T) of all wavelengths emitted by a black body to the whole hemisphere space with its temperature. Therefore, this law is obtained by combining wavelength with Planck's radiation law:
Mb(T)=∫0∞Mλb(T)dλ=σT4
Where σ = π 4c1(15c24) = 5.6697×10-8w/(m2 k4), which is called Stephen Boltzmann constant.
Stephen Boltzmann's law shows that any object with a temperature higher than Kelvin zero will spontaneously emit infrared thermal radiation, and the total radiation power per unit surface area of a blackbody is proportional to the fourth power of Kelvin temperature. Moreover, as long as the temperature changes slightly, the radiation power emitted by the object will change greatly.
Then, we can imagine that if we can detect the total radiation power per unit surface area of the blackbody, can't we determine the temperature of the blackbody? Therefore, Stephen Boltzmann's law is the basis of all infrared temperature measurement.
3. The law of spatial division of radiation-Lambert Cosine Law
The so-called Lambert cosine law means that the radiation intensity of a blackbody in any direction is proportional to the cosine of the angle between the observation direction and the normal of the radiation surface, as shown in the figure.
Iθ=I0COSθ
This law shows that the blackbody has the strongest radiation in the normal direction of the radiation surface. So, when actually doing infrared detection. Should be carried out as far as possible in the normal direction of the measured surface. If it is detected in the direction with an angle θ to the normal, the received infrared radiation signal will be weakened to COSθ times of the maximum value in the normal direction.
(2) the infrared radiation law of the actual object
1. Kirchhoff's law
The ratio M/α of radiation emissivity M(T) to absorption capacity α of an object has nothing to do with the properties of the object, and is equal to the radiation emissivity M0(T) of a blackbody at the same temperature. It shows that an object with a large absorption capacity has a large emission capacity. If the object cannot emit radiation energy of a certain wavelength, it will never absorb radiation energy of that wavelength.
2. Emissivity
Experiments show that the emissivity of an actual object depends not only on temperature and wavelength, but also on the material properties and surface state of the object. Here we introduce a radiation coefficient that varies with the material properties and surface state, and then we can apply the basic law of blackbody to actual objects. This radiation coefficient is usually called emissivity, or specific emissivity, and it is defined as the ratio of the radiation performance of an actual object to that of a blackbody at the same temperature.
The influence of wavelength is not considered here, but only the total emissivity of an object at a certain temperature is studied:
ε(T) = M(T)/M0(T)
The application of Stephen Boltzmann's law in practical objects can be expressed as:
M(T) =ε(T).σT4
(3) Emissivity and its influence on equipment status information monitoring.
An object must absorb, reflect and transmit a given incident radiation, and the sum of absorption α, reflectivity ρ and transmittance ρ must be equal to 1:
α+ρ+τ= 1
And its reflection and transmission parts remain unchanged. Therefore, under the condition of thermal balance, the radiant energy absorbed by the object must be converted into the radiant energy emitted by the object. It can be concluded that under the condition of thermal balance, the absorption rate of the object must be equal to the emissivity of the object at the same temperature:
α(T)=ε(T)
In fact, from Kirchhoff's law, we can also infer the above formula:
M(T)/ α(T)=M0(T)
ε(T) =α(T)
ε(T) = M(T)/M0(T)
Then for opaque objects ε(T) = 1-ρ(T)
According to the above formula, it is not difficult to qualitatively understand the following factors affecting emissivity:
1. Influence of different material characteristics
Different materials have different radiation absorption or reflection characteristics, so their emission characteristics should be different. Generally, when the temperature is lower than 300K, the emissivity of metal oxides is generally greater than 0.8.
2. Influence of surface state
The surface of any real object is not absolutely smooth, and it always shows different surface roughness. Therefore, this different surface morphology will affect the reflectivity, thus affecting the value of emissivity. The size of this influence also depends on the kind of material.
For example, for nonmetallic dielectric materials, the emissivity is very small or has nothing to do with surface roughness. But for metal materials, surface roughness will have a great influence on emissivity. Such as wrought iron, the surface condition is rough, and the emissivity is 0.94 at 300K; When the surface condition is polished and the temperature is 3 10K, the emissivity is only 0.28.
In addition, it should be emphasized that in addition to surface roughness, there are some human factors, such as adding lubricating oil and other deposits (such as paint, etc. ), will obviously affect the emissivity of the object.
Therefore, when testing, we must first make clear the emissivity of the measured object. In general, we don't know the emissivity, so we can only use the phase-to-phase comparison method to judge the fault. For power equipment, the emissivity is generally between 0.85 and 0.95.
3. Temperature influence
The influence of temperature on different objects is different, so it is difficult to make quantitative analysis.
Pay attention only when checking.
(4) the influence of radiation transfer between objects
As we discussed above, an object must absorb and reflect a given incident radiation. When it reaches thermal balance, its absorbed radiation energy will inevitably be converted into emitted radiation energy. Therefore, when we detect any object in the substation, the detected temperature will inevitably be affected by other objects nearby.
Therefore, when testing, we should pay attention to the direction and time of testing to minimize the influence of other objects.
(e) Effects of atmospheric attenuation
Atmospheric radiation to objects has physical processes such as absorption, scattering and refraction, which will attenuate the radiation intensity of objects, which is called extinction.
The extinction of the atmosphere is related to the wavelength and has obvious selectivity. There are three bands of infrared in the atmosphere that can be completely transmitted, which we call atmospheric window, and they are divided into near infrared (0.76 ~ 1. 1um), middle infrared (3 ~ 5um) and far infrared (8 ~ 14).
For power equipment, the temperature is mostly low, about 300K ~ 600K(27℃ ~327℃). In this temperature range, according to the basic law of infrared, it can be deduced that the infrared radiation signal emitted by the equipment has the largest percentage and the largest radiation contrast in the far infrared range of 8 ~ 14um. Therefore, most infrared detection instruments in power system work in the wavelength range of 8 ~ 14um.
But please note that even if you work in the atmospheric window, the atmosphere still has extinction effect on infrared radiation. In particular, water vapor has the greatest influence on infrared radiation. Therefore, when testing, it is best to keep the humidity below 85%, and the closer the distance, the better.
B:
Analysis of infrared thermal imaging technology
Human development can be divided into three stages. The first stage is the ability of human beings to expand their physical activities by making tools. In the second stage, by improving the judgment ability, we seek a clearer and broader standard for understanding and judging things; In recent years, human beings are committed to enhancing their ability to acquire input information, expanding the range of senses or adding new senses, so that our brains can accept more information, which is the third stage of human development. At this stage, the development of infrared technology has increased human senses from five to six.
In the Gulf War, high-tech weapons showed a broad platform of advanced technology, became the vane of the world's scientific and technological development, and also became the direction and focus of the world's competitive research and development. These high-tech technologies have therefore become new industries and investment hotspots, creating billions of wealth and unpredictable social benefits.
Among these new technologies, satellite positioning (GPS) and infrared thermal imaging (TIS) are two technologies.
Satellite positioning system (also known as GPS) has been widely used in all walks of life, from military to civilian, and has become a promising industry. The development speed of its application far exceeds people's expectations, such as in the widely used automobile anti-theft positioning system.
Infrared thermal imaging technology is also a promising high-tech technology, and its wide application will cause revolutionary changes in many industries.
1. What is infrared thermal imaging?
Light is familiar to everyone. What is light? Light is visible light, which is an electromagnetic wave that human eyes can feel. The wavelength of visible light is 0.38-0.78 micron. Electromagnetic waves shorter than 0.38 micron and electromagnetic waves longer than 0.78 micron are imperceptible to human eyes. Electromagnetic waves shorter than 0.38 micron are located outside the purple spectrum of visible light, which is called ultraviolet, while electromagnetic waves longer than 0.78 micron are located outside the red spectrum of visible light, which is called infrared. Infrared, also known as infrared radiation, refers to electromagnetic waves with a wavelength of 0.78~ 1000 micron. The part with a wavelength of 0.78~2.0 micron is called near infrared, and the part with a wavelength of 2.0~ 1000 micron is called thermal infrared.
Photos are obtained by camera imaging, and TV images are obtained by TV camera imaging, all of which are visible light imaging. In nature, all objects can radiate infrared rays, so different infrared images can be obtained by measuring the infrared difference between the target itself and the background with a detector. The image formed by thermal infrared rays is called heat map.
The thermal image of the target is different from the visible image of the target. What the human eye can see is not the visible image of the target, but the image of the temperature distribution on the surface of the target. In other words, infrared thermal imaging makes it impossible for human eyes to directly see the surface temperature distribution of the target, and it becomes a thermal image representing the surface temperature distribution of the target that human eyes can see.
2. What are the characteristics of infrared thermal imaging?
A famous American infrared scholar pointed out: "Human development can be divided into three stages. The first stage is to expand the ability of human body activity by making tools, and the second stage is to seek a clearer and broader standard of understanding and judging things by improving judgment ability. In recent years, human beings are committed to enhancing their ability to acquire input information, expanding the range of senses or adding new senses, so that our brains can accept more information, which is the third stage of human development. At this stage, the development of infrared technology has increased the number of human senses from five to six. " This sentence, I think, properly illustrates the importance of infrared imaging technology in the contemporary era. Because the objects around us can only emit visible light when their temperature is as high as 1000℃. In contrast, all objects around us whose temperature is higher than absolute zero (-273℃) will continuously emit thermal infrared rays. For example, we can calculate that the thermal infrared energy emitted by a normal person is about 100 watt. Therefore, thermal infrared (or thermal radiation) is the most extensive radiation in nature. In addition to its universality, thermal radiation has two other important characteristics.
1. The atmosphere and smoke clouds absorb visible light and near infrared rays, but are transparent to thermal infrared rays of 3~5 microns and 8~ 14 microns. Therefore, these two bands are called "atmospheric windows" of thermal infrared rays. Using these two windows, people can clearly observe the situation ahead in the completely dark night or in the battlefield with dense smoke. It is precisely because of this feature that thermal infrared imaging technology provides advanced night vision equipment in the military and installs all-weather forward-looking systems for aircraft, ships and tanks. These systems played a very important role in the Gulf War.
2. The thermal radiation energy of an object is directly related to the surface temperature of the object. This characteristic of thermal radiation enables people to use it to measure the temperature and analyze the thermal state of objects without contact, thus providing important detection means and diagnostic tools for industrial production, energy saving and environmental protection.
Third, infrared thermal imaging instrument
According to the characteristics that objects can emit infrared rays, various countries are competing to develop various infrared thermal imaging instruments.
1964, Texas instruments company (TI) successfully developed the first generation of thermal infrared imaging equipment, which is called infrared forward-looking system (FLIR). This device decomposes and scans the thermal radiation image of the target by using the moving machinery of optical elements, and then performs photoelectric conversion by using the photoelectric detector, and finally forms a video image signal, which is displayed on the screen. Infrared forward-looking system is still an important device on military aircraft, ships and tanks.
In the mid-1960s, AGA Sweden and Swedish National Power Bureau developed a thermal infrared imaging device with temperature measurement function on the basis of infrared forward-looking device. This second generation infrared imaging equipment is usually called thermal imager.
In 1970s, Thomson France developed an infrared thermal TV product without refrigeration.
In 1990s, there were two types of infrared thermal imaging products: cooled and uncooled focal plane infrared thermal imaging products. This is the latest generation of infrared TV products, which can be used in large-scale industrial production and improve the application of infrared thermal imaging to a new stage.
In 1970s, relevant units in China began to study infrared thermal imaging technology. By the early 1980s, China had made some progress in the development and production technology of long-wave infrared modules. By the end of 1980s and the beginning of 1990s, China had successfully developed a real-time infrared imaging prototype, and its sensitivity and temperature resolution reached a high level.
In the 1990s, China developed the key technologies such as low-noise broadband preamplifier and micro-refrigerator used in infrared imaging equipment, which have moved from experiment to application, and are mainly used in troops, such as portable field thermal imager, anti-tank missile, air defense radar, tanks and naval artillery.
China has invested a lot of manpower and material resources in infrared thermal imaging technology, forming a considerable R&D force, but overall there is a big gap with the world advanced level, which is about 10 years compared with the west.
At present, foreign countries have begun to equip the troops with the second generation infrared thermal imager, and started the research and development of the third generation, while China has only now popularized the first generation infrared thermal imager.
Internationally, the United States, France and Israel are pioneers in this field, while other countries, including Russia, are at the downstream level.
In recent years, under the guidance of the Party's policies and guidelines, China's infrared imaging technology has developed by leaps and bounds, and the gap with the West is gradually narrowing. The advanced nature of some equipment can also be synchronized with the west. I believe that the gap between China and the West will be further narrowed, especially in the application of new technologies.
Infrared thermal imaging products can be divided into two categories: refrigeration type and uncooled type. Infrared TV products and uncooled focal plane thermal imager are both uncooled products, and others are refrigerated infrared thermal imagers.
At present, the most advanced infrared thermal imager, its temperature sensitivity can reach 0.05 degrees Celsius. No matter day or night, it can detect enemies in the jungle with infrared instrument, and the farthest distance can reach 100 meters. As a frontier defense against smuggling, it can also track big flies smuggled at sea, with a distance of several kilometers.
Thermal imager can not only observe the target in real time, but also make dynamic analysis through the "thermal trace" of its trajectory, because the thermal divergence of general objects takes a certain time, and some objects need a long time. For example, the kitchen smoke lit by the army and the vehicles that have already started can leave "heat traces".
The first generation thermal imager is mainly composed of optical instruments with scanning devices, electronic amplification circuits, displays and other components. The troops have been successfully equipped and made important contributions to ground observation, aerial reconnaissance and surface insurance at night.
The second generation thermal imager mainly adopts focal plane array technology, integrates tens of thousands or even hundreds of thousands of signal amplifiers, and places the chip on the focal plane of the optical system to obtain a panoramic image of the target, which greatly improves the sensitivity and thermal resolution, and can further improve the detection distance and recognition ability of the target.
The third generation thermal imager is also under development.
Fourth, the role of infrared thermal imager in fire fighting
In a large area of forest, fires are often caused by inconspicuous hidden fires. This is the source of devastating fire, and it is difficult to find this hidden fire sign with the existing common methods.
However, these hidden fires can be found quickly and effectively by patrolling with planes and using infrared thermal imaging devices, and the fires can be eliminated in the bud.
Canada Forestry College began to carry out forest fire prevention test as early as 1975 to check the potential fire sources of unlit land from the plane. The Forest Research Center of Canada used helicopters to carry AGA750 portable thermal camera, and found 15 fire hazards in a fire season.
Spontaneous combustion often occurs in grain granaries, which is often long-term, intense and costly. At present, thermometers are generally used to measure the temperature changes in granaries to prevent them from happening. Using thermal imager can accurately determine the location and scope of these fires, so as to know, prevent and extinguish them early. It is convenient, simple, quick and timely to use the thermal imager.
Infrared thermal imager can also be used to detect poor contact and overheated mechanical parts of electrical equipment to avoid serious short circuit and fire.
During the four years from 1980 to 1983, China used a self-made thermal imager to check the overheating of more than 10000 plugs in 20 power plants, 8 substations and 24 high-voltage lines in North China Power Grid, and found more than 500 abnormal hot spots, with severe overheating of 100. Due to the timely treatment, no fire accident occurred.
In foreign countries, the statistics of American insurance companies show that more than 25% of all hidden dangers of electrical equipment are the main causes of fire, which are caused by poor contact of plugs. Therefore, the electrical maintenance manual 70B of the National Fire Protection Association of the United States stipulates that any electrical plug should not be tightened in the future as long as the torque value remains unchanged after being tightened according to the specified torque. Therefore, a well-made and normally installed electrical plug does not need to be fastened regularly at all, and only needs to be handled when its function is abnormal and overheated.
For all devices that can be seen directly, infrared thermal imaging products can determine the thermal hazards of all connection points. For those parts that cannot be directly seen due to occlusion, we can find their thermal hidden dangers according to the heat conduction to external parts. In this case, the traditional method has no choice but to disassemble, inspect and clean the joint. Infrared thermal imaging products can not replace the operation test of circuit breakers, wires, buses and other components. Infrared thermal imaging products can easily detect loop overload or three-phase load imbalance.
MAI company of the United States used infrared thermal imaging products to inspect many general electric preventive equipment, and found that many equipment still had electrical faults after maintenance. For example, an important electronic product manufacturer, this company carries out power outage maintenance on its electrical equipment every two years. During power failure, equipment cleaning, fastening of all connection points and tripping test of circuit breakers shall be carried out. The installation of high and low voltage switchgear was tested. The inspection of infrared thermal imaging products after traditional maintenance still found some hidden dangers. Serious hidden trouble was found on different equipment 19 and general hidden trouble 179. These serious hidden dangers mean that the surface temperature of the tested equipment exceeds the maximum design temperature of NEMA or UL. Most hidden dangers exist in motor control equipment, and some hidden dangers also exist in switch cabinets and power boards. Another example is that after the fire broke out in the main motor control center of the federal government office building, preventive maintenance was carried out every six months. After the fire, it was repaired twice, and the infrared thermal imaging products were inspected. The results show that there are three serious hidden dangers before preventive maintenance and three serious hidden dangers after preventive maintenance. Therefore, the necessity of infrared thermal imaging product detection is obvious.
In addition, using infrared thermal imaging products instead of traditional cleaning and fastening methods can save a lot of money. There are two reasons for this saving: first, the inspection speed of infrared thermal imaging products is very fast, instead of spending a lot of manpower to clean and fasten the equipment like traditional methods. In addition, when the infrared thermal imaging products are inspected, the equipment is not required to be powered off. Only after the hidden dangers are found out, the power off is required for a short time during maintenance. Moreover, the power outage of individual hidden dangers is only partial, and the power outage time is very limited, and maintenance may even be arranged within the planned power outage time. Here are a few examples.
1), an American asset management company implemented a complete maintenance project including all motor control equipment, lighting, power boards and switchgear (excluding circuit breaker trip test). The charging standard depends on the workload. The average maintenance cost of a typical office building (250,000 square feet, 65,438+00 floors) is $6,500. The inspection of infrared thermal imaging products in the same building can complete the inspection of all motor controls, switchboards and switch cabinets (including various mechanical equipment) in one day, and the inspection service fee for infrared thermal imaging products is about 600 to 800 US dollars. Therefore, the cost of infrared thermal imaging products is only110 of the traditional method.
2) Before signing the inspection contract of infrared thermal imaging products, an electronic equipment factory spent four days without power, and three groups of five electricians carried out traditional maintenance. Workers work 65,438+02 hours a day to clean and fix all connection points of switchgear, motor control equipment and power board. The labor cost of these jobs is 30 thousand dollars. The inspection of infrared thermal imaging products of the same equipment was also carried out for 4 days, with the assistance of two factory workers, and the cost was only $3,000.
3) The large office/hotel/sales commercial complex will maintain the traditional high and low voltage switchgear once every three years, and at least $20,000 will be spent on cleaning and fastening during the maintenance period. It only takes 12 hours and only $2,000 to check the infrared thermal imaging products of the same equipment, and 12 hidden dangers are found, two of which are serious hidden dangers that can cause fires.
4) Through the inspection and analysis of infrared thermal imaging products, the annual consumption of a small American factory will be reduced from 160 to 40 working hours. If you save 120 hours a year at the cost of $25/hour (including overtime), you can save $3,000.
According to the above-mentioned American experience, replacing the regular cleaning and fastening work in traditional maintenance with infrared thermal imaging product inspection can save 50%-90% of the cost and effectively prevent the occurrence of fires. For example, during July and August of 1985, Washington post described on the front page the fire, personal injury, property loss, production and tax losses caused by many electrical equipment power failure accidents that happened almost every day. For example, a power failure accident at a local hotel caused a loss of $6.5 million. In order to avoid the above-mentioned power failure accidents, many commercial and industrial organizations often spend a lot of money on preventive maintenance. Unfortunately, these jobs often fail to find hidden dangers, and may also cause new electrical hidden dangers. Therefore, the infrared thermal imaging product inspection of electrical equipment can replace the traditional preventive maintenance work in many aspects.
American No.375 Technical Bulletin on Equipment Operation and Production Control points out that both new and old buildings can benefit from the detection of infrared thermal imaging products. Nearly 50 companies in the United States provide inspection services for infrared thermal imaging products, and conduct infrared thermal imaging inspection for all customers' electrical equipment and distribution systems, including high-voltage contactors, fuse panels, main power circuit breaker panels, contactors, and all distribution lines, motors, transformers, etc. To ensure that all electrical equipment operated by customers has no potential thermal hazards and effectively prevent fires. The statistics of American insurance companies also show that the inspection of infrared thermal imaging products for all electrical equipment can greatly reduce unsafe factors.