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Can Variable Frequency Drives Save Your Energy Costs?
Can Variable Frequency Drives Save Your Energy Costs? Image Source: unsplash Variable frequency drives (VFDs) play a crucial role in modern energy management. Canroon frequency converter control AC induction motors by adjusting the frequency and voltage, which optimizes motor performance. This technology can lead to significant energy savings, with studies showing reductions in energy costs ranging from 10% to 70%. By understanding how VFDs function, industries can harness these benefits, achieving up to 50% savings in sectors like water treatment. The ability to match motor speed with demand not only conserves energy but also extends equipment life, making VFDs an essential tool for cost-effective operations. Understanding Variable Frequency Drives Image Source: pexels Basic Functionality How VFDs Control Frequency and Voltage Variable frequency drives (VFDs) adjust the speed of AC induction motors by controlling the frequency and voltage supplied to the motor. This precise control allows the motor to operate at the optimal speed for the task at hand. By varying these parameters, VFDs ensure that motors do not run at full speed unnecessarily, which conserves energy and reduces wear on the equipment. Impact on AC Induction Motors The impact of VFDs on AC induction motors is profound. They eliminate the need for energy-wasting devices like outlet dampers or pressure control valves. Instead, VFDs adjust motor speed to match the system's load requirements, leading to more efficient operation. This capability not only reduces energy consumption but also extends the lifespan of the motor by minimizing mechanical stress. Benefits of Using VFDs Energy Efficiency VFDs offer substantial energy efficiency benefits. By matching motor speed to load demands, they significantly reduce power consumption. For instance, in pumping applications, VFDs can adjust the flow and pressure output to meet changing conditions, resulting in large energy savings. The ability to operate motors at partial loads, a common scenario, enhances these savings further. Cost Reduction The cost reduction potential of VFDs is equally impressive. By providing soft-start and soft-stop capabilities, VFDs reduce mechanical stress, which extends the life of both the motor and connected equipment. This longevity translates into lower maintenance costs and fewer replacements. Additionally, VFDs allow for precise control, enabling operations to run only as needed, thus cutting down on unnecessary energy expenditure. Optimizing Motor Performance Matching Variable Load Profiles Importance of Load Matching Matching motor performance to variable load profiles is crucial for energy efficiency. When motors operate at full speed regardless of demand, they waste energy. Variable Frequency Drives (VFDs) address this issue by adjusting motor speed to align with the actual load requirements. This alignment ensures that motors consume only the necessary amount of energy, reducing waste and enhancing overall efficiency. Industries that implement VFDs often see a significant decrease in energy costs, with savings ranging from 10% to 20% compared to traditional fixed-speed systems. Techniques for Optimization Several techniques can optimize motor performance using VFDs. First, analyzing load profiles helps determine the optimal speed settings for different operational phases. Second, integrating sensors and control systems allows for real-time adjustments, ensuring that motors operate efficiently under varying conditions. Third, regular maintenance and calibration of VFDs ensure they function correctly, maximizing their energy-saving potential. By employing these techniques, industries can achieve substantial energy savings and improve the longevity of their equipment. Energy Savings Potential Quantifying Savings Quantifying the energy savings potential of VFDs involves comparing them to traditional motor starter relays. Canroon VFDs can reduce energy costs by an average of 10% to 70%, depending on the application and load variability. For instance, upgrading from full fixed-speed pumps to VFD systems can result in energy cost savings of over 20%. These savings not only cover the initial investment in VFD technology but also contribute to long-term financial benefits. Long-term Benefits The long-term benefits of using Canroon VFDs extend beyond immediate energy savings. By reducing mechanical stress through soft-start and soft-stop capabilities, VFDs prolong the lifespan of motors and connected equipment. This durability translates into lower maintenance costs and fewer replacements over time. Additionally, the precise control offered by VFDs allows operations to run more efficiently, further reducing operational costs. As industries continue to prioritize energy efficiency, the adoption of VFDs will likely increase, offering both economic and environmental advantages. Applications of VFDs Manufacturing Industry Enhancing Efficiency Canroon Variable Frequency Drives (VFDs) significantly enhance efficiency in the manufacturing industry. They optimize motor speed and torque, aligning them with the specific demands of production processes. This precise control minimizes energy waste and reduces operational costs. By adjusting motor speeds to match the exact requirements of each task, VFDs ensure that machinery operates at peak efficiency. This not only conserves energy but also extends the lifespan of equipment by reducing mechanical stress. Case Studies Several case studies highlight the impact of Canroon VFDs in manufacturing. For instance, a leading automotive manufacturer implemented VFDs across its assembly lines. The result was a 25% reduction in energy consumption and a noticeable decrease in maintenance costs. Another example involves a textile company that integrated VFDs into its spinning machines. This change led to a 30% increase in production efficiency and a significant drop in energy expenses. These examples demonstrate the transformative potential of Canroon VFDs in enhancing industrial operations. HVAC Systems Speed and Torque Control In HVAC systems, VFDs play a crucial role in controlling speed and torque. They adjust fan and pump speeds to match the building's heating and cooling demands. This capacity modulation ensures that the system operates efficiently, reducing energy consumption and wear on components. By balancing fan and pump operations, VFDs maintain optimal indoor conditions while minimizing energy use. This precise control also reduces stress on HVAC components, extending their service life and lowering maintenance costs. Real-world Examples Real-world examples underscore the effectiveness of VFDs in HVAC systems. A case study by Schneider Electric revealed a 35% decrease in energy consumption after implementing VFDs in a commercial HVAC system. The VFDs adjusted fan speeds based on real-time demand, resulting in more efficient energy use. Another example involves a large office building that installed VFDs to manage its HVAC operations. The outcome was a 40% reduction in energy costs and improved occupant comfort. These examples illustrate how VFDs can transform HVAC systems, making them more efficient and cost-effective. Versatility of VFDs Induction Heating Systems Role of VFDs Variable Frequency Drives (VFDs) play a pivotal role in induction heating systems. They control the speed and frequency of induction motors, which are essential for precise temperature management. By adjusting these parameters, VFDs ensure that the heating process remains consistent and efficient. This control enhances the quality of the final product and reduces energy consumption. Advantages in Heating Applications In heating applications, VFDs offer several advantages: Energy Efficiency: VFDs optimize power usage by matching motor speed to the specific heating requirements, leading to significant energy savings. Process Control: They provide precise control over heating rates, which improves process accuracy and product quality. Reduced Wear: By minimizing mechanical stress, VFDs extend the lifespan of heating equipment, reducing maintenance costs. Other Potential Uses Emerging Technologies VFDs are finding applications in emerging technologies. They are integral to renewable energy systems, such as wind and solar power, where they manage the variable output of these sources. In electric vehicles, VFDs control motor speed and torque, enhancing performance and efficiency. Future Prospects The future prospects for VFDs are promising: Smart Grids: VFDs will play a crucial role in smart grid technology, optimizing energy distribution and reducing waste. IoT Integration: As the Internet of Things (IoT) expands, VFDs will integrate with smart devices, allowing for real-time monitoring and control. Sustainability: With a focus on sustainability, industries will increasingly adopt VFDs to reduce carbon footprints and improve energy efficiency. VFDs continue to evolve, offering innovative solutions across various sectors. Their versatility makes them indispensable in modern energy management. Considerations for Implementation Initial Costs and ROI Investment Analysis Investing in Variable Frequency Drives (VFDs) requires careful financial analysis. The initial costs of VFDs exceed those of traditional motor starter relays. However, the long-term benefits justify this investment. Businesses should evaluate potential energy savings, productivity gains, and reduced maintenance costs. These factors contribute to a comprehensive understanding of the financial impact. A detailed investment analysis helps businesses make informed decisions about adopting VFD technology. Return on Investment The return on investment (ROI) for VFDs often proves favorable. Typically, VFDs pay for themselves within two years due to significant energy savings. For example, reducing motor speed by 20% can lead to a 50% reduction in energy consumption. This efficiency translates into substantial cost savings over time. Businesses can realize notable financial benefits by implementing VFDs, making them a wise investment for long-term operational efficiency. Technical Considerations Installation Requirements Installing Canroon's VFDs involves specific technical requirements. Proper installation ensures optimal performance and longevity. Technicians must consider factors such as electrical compatibility, space constraints, and cooling needs. Ensuring that the installation environment meets these criteria is crucial. Additionally, integrating VFDs with existing systems may require adjustments to control settings and wiring configurations. Addressing these technical aspects during installation minimizes potential issues and maximizes the effectiveness of VFDs. Maintenance Needs Regular maintenance is essential for the continued performance of VFDs. Routine checks and servicing help identify potential issues before they escalate. Maintenance tasks include inspecting electrical connections, cleaning cooling fans, and updating software. By adhering to a consistent maintenance schedule, businesses can extend the lifespan of their VFDs and maintain energy efficiency. Proper maintenance not only reduces downtime but also enhances the overall reliability of the system.   Canroon's Variable Frequency Drives (VFDs) offer substantial benefits in reducing energy costs. They optimize motor performance, leading to significant savings. For instance, a user reported a 300% reduction in energy consumption by adjusting pump speeds for irrigation systems. To implement VFDs effectively, industries should conduct thorough investment analyses and ensure proper installation and maintenance. As technology advances, VFDs will play a pivotal role in energy management. Their ability to enhance efficiency and reduce operational costs makes them indispensable in the pursuit of sustainable energy solutions.
Does Frequency converter better than control valves in flow controls?
I'm hearing about using a frequency converter with my pump and motor setup for better flow control instead of control valves. Is it worth it? Do I still need some measure of flow control besides a shut-off valve?     1.Good points and bad points I think a frequency converter control can offer better efficiency, but diminished control accuracy, response time and shut-off performance. It is not as reliable as a regular control valve scheme. If we need efficiency and performance, we can consider using a frequency converter system as a core control and a valve (maybe a ball valve) as a fine control. The valve should always be 90% open to keep the throttling loss down. The valve can also be used for shut-off purposes to improve the response time and leakage performance. 2.Need both for key applications If the fluid being pumped is a critical fluid, a key raw material process intermediate with flow parameters that directly affect product quality or safety of the process, I would say that controlling the fluid flow via both frequency converter control and a flow-control valve/loop makes sense (for redundancy protection). In my estimation, the costs associated with a frequency converter are quite a bit less. We use frequency converters to control many of our processes here, and they have shown themselves to be reliable. 3.Not for everywhere, yet We have experience using the inverters to control the combustion air flow of Boilers FD fans and cooling tower water supply pumps. They all worked fine. We are also aware that one of our clients is using frequency converters for ground well pumps without any complaints. However, we advise cautious review of lower range conditions for case-by-case application, since the discharge pressure also goes down faster than flow when we try to control the flow. We still do not feel comfortable and confident using frequency converters to control flow in critical areas like boiler feed water pumps. 4.Holds reflux pump prime We have been quite pleased with frequency converters replacing control valves in reflux pump service. Control is excellent, a source of leakage is eliminated and, during upsets the reflux pumps do not lose prime, an important safety consideration. In services pumping against lower heads, once flow is established, siphoning can set a minimum flow rate. If you need to hold lower flows then you have to put up with control valves. Substituting frequency converters for control valves has other advantages: energy is conserved, the power factor is improved, pump design is simpler, impeller sizing is more uniform, seal life is longer, and smaller installations cost less. frequency converters are not as robust as electric motors during power flickers and lightning strikes, so isolation transformers are desirable and sparing policy needs to be reviewed. No problem with harmonics has ever come to our attention, but much has been written on the subject. The short distances we have between pumps and frequency converters are thought to minimize this problem. Control is excellent as long as siphoning is avoided and the suction pressure never exceeds the discharge pressure. If it does, control is lost. For this reason, we use frequency converters to control reflux pumps, but not bottoms or tank transfer pumps. frequency converters are so much of an improvement that we would no longer take a reflux control valve if it were given to us. 5.Holds pressure setpoints For the system I have described, there are no control valves used other than shut-off valves. One significant advantage to using a frequency converter is that the power consumed by the pump is typically less for a unit operating at a reduced speed, as compared to a 60 Hz operating speed with a control valve. A flow control valve is turning a lot of energy into wasted heat. The additional cost of a frequency converter is often recaptured in a very short time from the reduced power costs and simplified operation. 6.Might cost more, but worth it A frequency converter to control flow may require more capital than a control valve and a normal motor on your pump. However, it does save energy instead of burning the pump energy across the control valve. Additionally, a control valve and its associated problems with leakage and sticking stem are eliminated. The control parts are all electronic and not wetted, except for the pump. This is especially important in handling corrosive materials. Furthermore, because wear is related to some higher power of speed, the bearings and seal on a pump frequency converter at less than its normal speed should last longer. Of course, there is no free lunch. There are safety considerations for your particular process. The price you pay is that there is no emergency shut-off. In a power failure, the pump stops pumping. You may need to automate a block valve if you require positive shut-off. 7.Mind the harmonics There is another factor to consider. If a facility is considering this replacement for multiple large AC frequency converter circuits, the power distribution system should be evaluated for the possible detrimental effects of too much harmonic distortion. frequency converters are known to cause changes in the sine waveform because of the way power electronics draw current, and these changes (distortions) are known to occur in integer multiples of the electrical frequency (or harmonics). In a typical three-phase system, if the phases are balanced, there is no (or not much) current load on the neutral. The addition of lighting circuits and electronic frequency converters add harmonic distortion which, if the system impedance is high enough and the power is distorted enough, can affect other equipment,"especially electronic equipment, including computer systems, electronic instruments, and even frequency converters themselves. It is known that feedback due to harmonics can be additive on the neutral, causing significant current where there shouldn't be any, and problems are sometimes seen, such as breakers that trip when the measured power draw doesn't exceed their setpoint, premature motor failures, and transient effects that can be very difficult to troubleshoot. The secondary cost of filters and other apparatus to clean up the power to distortion-sensitive equipment on the same power system as the frequency converters may need to be considered, especially if the frequency converter(s) power consumption is a significant percentage of total usage. 8.Harmonics and overheating Frequency converter is reliable and energy efficient. You need to make sure your wiring and motor are VF ready (voltages can be higher and harmonics can impact motor life.) Also, if the anticipated speed is too low, motor cooling can be a problem (the fan runs too slow to move enough air), so auxiliary air moving can be a problem, especially on larger motors. Overall, we have found using frequency converters for flow or pressure control to be very effective and they save money both in power costs and in maintenance. 9.Watch out for low flows A frequency converters solution is no different than controlling the speed of a steam turbine in order to regulate flow from a compressor. It's just becoming more common, with advances in electronics and with the increased availability of frequency converters and motors for this service. Things to be aware of: 1) The frequency converter may have a minimum speed, so don't look for it to control well at extremely low flows. 2) Pumps with long shafts (especially vertical pumps) can have a natural (critical) frequency that the frequency converter could allow the pump to run at. This will lead to a number of reliability problems in these pumps. 3) If a dual-gas seal is used, it has a minimum speed that it needs to run at in order for the seal faces to lift off.' This minimum speed will depend on seal size and design, but will be on the order of a few hundred rpm. 10.Many advantages with frequency converter Much of whether to use a control valve vs. an AC frequency converter has to do with what the product is, the type of pump, and the entire piping scheme. The advantages of the frequency converter are energy savings, maintenance, information (feedback), and future control flexibility, if the rest of the system changes. Some people would argue cost savings as well but that may well depend on sizing, etc. Typically, I prefer the frequency converter approach over control valves, but they have limitations such as ambient conditions, etc., that must be taken into account. In most cases, I feel it is definitely "worth it", and you should not need any other method of flow control unless you are feeding a multiple piping loop system such as chilled water to multiple HVAC units or heat exchangers, etc. If you are going to use a frequency converter in a remote location, it can be an advantage because most will be able to provide the localized PID control for closed-loop performance without having to purchase other control equipment or long cable runs from a PLC. 11.Location, location We use frequency converters for flow control as much as possible. A pump pumping against a valve wears both of them out. Make sure that the motor is for inverter duty and install the frequency converter in a "nice" place. Under conduit entries or HVAC ducts are not nice places. We have between 100-200 frequency converters installed and go weeks without a frequency converter problem. frequency converters are intelligent and some can be viewed or downloaded from any Ethernet-networked computer. They can act as remote I/O and give percent load and Hz, and be started and stopped with only a communication cable from a PLC, which lowers installation cost. They have stall and overload protection built in. 12.Beats buying stainless A steam turbine or a frequency converter/motor will work very well for flow control. Applications to centrifugal pumps and positive displacement pumps can be successful. Since the power required for a centrifugal pump varies with the cube of RPM, overheating at low RPM (diminished cooling fan performance) is usually not a problem. We usually include a low limit on the speed to prevent motor overheating that might occur if the pump is run near stall conditions. Constant-torque loads need to be evaluated more carefully. For modest-sized 480 V motors, the installed cost of a frequency converter is usually less than the cost of a control valve when stainless steel valves are required. If the pump (not the frequency converter) is in an explosion hazard area, pay careful attention to heating and make sure the NEC or applicable code requirements are met. 13.Back in the day Allow me to refer to a 50-year-old technique I used that performed extremely well for the control of feed flow to large filters. It consisted of a U.S. frequency converter with a Control flow air operator responding from a mag flow meter. The frequency converter consisted of the constant-speed motor driving two variable-speed sheaves positioned by the pneumatic operator. Crude and simple, but it did an excellent job. Certainly the precision was not as exacting as a solid-state electronic motor control system, but those were the good old days. Also in those ancient days in the paper industry, we used DC motors driven by Thyratron tubes for speed control of paper rewinders, in which role diameter was constantly changing although sheet feed was constant. Of course, the thyratrons are now replaced by solid-state electronic output signals. They too worked very well. Ah, those good old days when simplicity prevailed. 14.Works great. Less money The big advantage to controlling flow with a frequency converter instead of a control valve is not improved control, but energy savings because you use only as much horsepower as you need instead of burning excess across the valve. 15.We do it without frequency converters Our process deals with a chemical that crystallizes out easily when the temperature is reduced or when flow is restricted. We tried control valves, but the restriction in the pipe caused more crystallization and made control very unreliable or uncontrollable. The solution was to use the same pumps we've been using to give a constant pressure, but now to regulate the pressure they operate at, thus controlling the flow. The final setup for liquid control has worked very well in a PLC-based system. An electromagnetic actuator controls the pressure at which the pneumatic diaphragm pumps to pump the liquid through the system and a nonintrusive magmeter monitors the flow.
Frequency Converter Troubleshooting
Frequency converters can be powerful tools in maintaining processes by using diagnostics to solve frequency inverter performance issues and troubleshoot related processes. An understanding of how the frequency converter interacts with the process can help you improve overall production and product quality   Frequency converters are not infallible; sometimes they need to be repaired or replaced. The frequency converter is often the first indicator of a process change or application problem. Many frequency converters communicate using an LCD or LED display, or through an open interlock or fault indication. In most applications, the frequency converter interacts with operator controls, process control signals, and PLCs. A problem with the interaction between the frequency converter and these external controls may appear to be a frequency inverter issue, when actually the problem is with the process. Discussing process and frequency inverter symptoms with the machine operators often can help determine the problem area. If the external controls are working correctly, use the frequency converter to identify problems systematically. If the display status indicator does not operate, verify incoming ac power. If the status indicator still does not display after verifying or restoring ac power, then verify control power, and restore it if necessary. If the frequency converter has been operating successfully, but suddenly fails to start, or if the frequency inverter starts but does not run properly, check to see if the diagnostics status display indicates a fault. The instruction manual for the frequency converter should have a description of faults and troubleshooting steps. Use diagnostics or a keypad control to monitor variables such as incoming voltage, dc bus, carrier frequency, output frequency, voltage, current, and I/O and control status. These parameters are displayed on most common frequency converters. I/O status uses bits to monitor required start conditions to ensure they are enabled and to determine what may be inhibiting start. Control status indicates the source of the speed reference and can be used to verify incoming speed or direction signals. High bus fault High bus is a common fault caused by external factors. An instantaneous voltage spike in the ac line or an "overhauling load" created by the inertia of the machine can cause a high bus fault. The load continues to rotate faster than the motor's commanded speed. When this situation occurs, the frequency converter protects itself by tripping on a high bus fault and shutting off the insulated gate bipolar transistors (IGBTs). If a high bus fault is indicated, ensure that the ac power supply is consistent and that the deceleration time is adjusted to match the capability of the load. If the process requires rapid deceleration, dynamic braking or a regenerative power control circuit may be added. Overcurrent fault Another common fault is overcurrent. When troubleshooting overcurrent faults, first check all power connections to ensure that they are properly attached. Loose connections or broken conductors frequently are culprits when overcurrent and control problems occur. Loose power connections cause overvoltage and overcurrent conditions, blown fuses, and frequency converter damage. Loose control wiring causes erratic frequency inverter performance, resulting in unpredictable speed fluctuations or the inability to control the frequency converter. Use an autotuning feature if it is offered on the frequency converter. The autotuning function on many frequency inverters enables the frequency inverter to identify the attached motor, allowing rotor information to be used in the processor algorithms for more accurate current control. The frequency converter also can compensate for flux current, allowing better control of the torque-producing current. Both over and under fluxing the motor can be troublesome. The second step is to check the mechanical load for worn or broken parts, or excessive friction. Repair or replace components as needed. Finally, check incoming voltage and acceleration rate. If incoming voltage is too low, or the acceleration rate is set too fast, an overcurrent fault is possible. Decrease the acceleration rate or stabilize incoming voltage to correct this fault. High starting-load current High current/load readings may indicate mechanical binding or unexplained changes in process speed or load. The power requirements for many pumps and fans increase proportional to the cube of the rotational speed (S3). Running loads just a few revolutions per minute faster can overload a frequency converter. Components should be checked before startup to avoid an overload situation. Conveyors left loaded during off hours should be unloaded before startup. Clogged pumps should be avoided by cleaning out solids that have settled while the pump was not in use. Avoid ice or moisture that possibly could form on the load. Wet material is heavier than dry and can place more loading on the conveyor, causing motor and frequency converter overload. One way to reduce a high starting load is to use a frequency converter with an extended acceleration rate. This feature starts a load slowly and smoothly rather than jerking it to a start. This type of start is easier on mechanical components and has lower line requirements because the frequency converter draws only 100% MDASSML 150% of load. Erratic operation If the frequency converter is functioning erratically, but a fault is not indicated, external factors may be the cause, or the frequency inverter itself may have failed. Understanding the causes of frequency converter faults helps you determine the root cause of the problem. Frequently overlooked root causes are usually instabilities in the process that force the frequency converter to function in harsh conditions. Visually inspect the frequency converter for burned or overheated components by looking for signs of discoloration or cracking. Burned or cracked components prevent proper frequency converter operation. Replace defective components and test the frequency converter before returning it to operation. Power quality is another electrical issue that can affect a frequency converter. A change in utility equipment or unexpected power surges, due to electrical storms or system overloads, can affect frequency converter performance. Contamination failure Contamination is a preventable cause of frequency converter failure. Check the frequency converter for contamination of dust, moisture, or other airborne particles that may be electrically conductive. Tracking or arcing marks across components or circuit board traces indicate evidence of contamination failures. If contamination is excessive, the frequency converter must be isolated from the contamination source by changing the environment or providing an appropriate NEMA-rated enclosure. If there is significant airborne contamination from dust, moisture, or corrosive vapors, the frequency converter must be in at least a NEMA-12 enclosure. The internal cooling fans and component heatsinks of the frequency converter also should be checked for contamination. Blocked fans force the frequency converter to operate outside of its temperature specification, which can cause premature failure as a result of inadequate cooling. Check the fan for grease and other contaminants that can cause bearings and other parts of the fan to fail. Both the interior and exterior of the frequency converter, including fans, blowers, filters, and heatsink fins, should be cleaned monthly to reduce the risk of failure from contaminants.  
Why choose induction heating?
The advantages of induction heating: ① There is no need to heat the whole, the deformation of the workpiece is small, and the power consumption is small. ②No pollution. ③The heating speed is fast, and the surface oxidation and decarburization of the workpiece is lighter. ④The surface hardened layer can be adjusted as required, which is easy to control. ⑤The heating equipment can be installed on the mechanical processing production line, which is easy to realize mechanization and automation, easy to manage, and can reduce transportation, save manpower, and improve production efficiency. ⑥The martensite structure of the hardened layer is finer, and the hardness, strength and toughness are higher. ⑦After surface quenching, the surface layer of the workpiece has a larger compressive internal stress, and the workpiece has a higher fatigue resistance. The future characteristics of induction heating equipment as the degree of automation control of induction heat treatment production lines and the high reliability requirements of power sources increase, it is necessary to strengthen the development of complete sets of heating process devices. At the same time, the induction heating system is developing towards the direction of intelligent control. The induction heating power supply system with intelligent computer interface, remote control and automatic fault diagnosis, miniaturization, suitable for field operations, high efficiency and energy saving control performance is becoming the future development goal.     The induction heating can be used in a variety of occasions, mainly include: （ 1 ）Metallurgy: smelting of non-ferrous metals, heat treatment of metal materials, stealing heat in the production of forging, extrusion, rolling and other profiles; welds in the production of welded pipes. （ 2 ）Machinery manufacturing: quenching of various mechanical parts, and heating for heat treatment such as tempering, annealing and normalizing after quenching. Diathermy before pressure processing. （ 3 ）Light industry: the sealing of cans and other packaging, such as the sealing packaging of the famous Tetra Pak brick. （ 4 ）Electronics: heating for vacuum degassing of electron tubes。