What are the necessary guides for the selection of series intermediate frequency furnaces and parallel intermediate frequency furnaces?
With the development of the era of science and technology, many industrial places will use high-tech machines, but environmental protection and energy saving are also conditions that people want to follow, so what kind of machine should be used? Selection of furnace and parallel intermediate frequency furnace, what are the necessary guides for purchase? Selection of series intermediate frequency furnace and parallel intermediate frequency furnace The difference between series intermediate frequency furnace and parallel intermediate frequency furnace is due to the different oscillation circuits they use. The former uses L, R and C in series, which is L, R, and C in parallel. As a foundry, should you choose a series intermediate frequency furnace or a parallel intermediate frequency furnace? Although this needs to be based on your own actual situation, you must first find out what are the similarities and differences between the two, and what are the advantages and disadvantages of each, and then you can make the right one. choose. This article makes a simple comparison between the series intermediate frequency furnace and the parallel intermediate frequency furnace. The main differences are as follows: 1. The load circuit of the series intermediate frequency furnace presents a low impedance to the power supply and requires a voltage source to supply power. Therefore, the rectified and filtered DC power supply At the end, a large filter capacitor must be connected in parallel. When the inverter fails, the surge current is large and the protection is difficult. The load circuit of the parallel intermediate frequency furnace presents a high impedance to the power supply, which requires a current source to supply power, and a large reactor needs to be connected in series at the end of the DC power supply. However, when the inverter fails, because the current is limited by the large reactance, the impact is not large, and it is easier to protect. 2. The input voltage of the series intermediate frequency furnace is constant, the output voltage is a rectangular wave, and the output current is similar to a sine wave. The commutation is carried out after the current on the thyristor crosses zero, so the current always leads the voltage φ angle. The input current of the parallel intermediate frequency furnace is constant, the output voltage is approximately sine wave, and the output current is a rectangular wave. That is to say, both are working in capacitive load state. 3. The series intermediate frequency furnace is powered by a constant voltage source. In order to prevent the upper and lower bridge arm thyristors of the inverter from being turned on at the same time, resulting in a short circuit of the power supply, when commutating, it must be turned off first and then turned on. That is, there should be a period of time (ta) that keeps all thyristors off. The stray inductance at this time, that is, the induced potential generated on the lead inductance from the DC terminal to the device, may damage the device, so it is necessary to select a suitable surge voltage absorption circuit for the device. In addition, in order to ensure the continuous load current and protect the thyristor from the high voltage on the commutation capacitor during the turn-off period of the thyristor, a fast diode must be connected in anti-parallel across the thyristor. The parallel intermediate frequency furnace is powered by a constant current source. In order to avoid a large induced potential on the filter reactance I.d, the current must be continuous. That is to say, it must be ensured that the thyristors of the upper and lower arms of the inverter are turned on first and then turned off during commutation, that is, all thyristors are in the on state during the commutation period (t). At this time, although the inverter bridge arm is straight through, because L is large enough, it will not cause a short circuit of the DC power supply, but the long commutation time will reduce the system efficiency, so it is necessary to shorten t, that is, reduce the value of Lk. 4. The operating frequency of the series intermediate frequency furnace must be lower than the natural oscillation frequency of the load circuit, that is, a suitable ta time should be ensured, otherwise the commutation failure will be caused by the direct connection of the upper and lower bridge arms of the inverter. The operating frequency of the parallel intermediate frequency furnace must be slightly higher than the natural oscillation frequency of the load circuit to ensure that there is a suitable back pressure when t, otherwise it will cause the commutation failure between the thyristors; but if it is too high, the thyristor will fail when commutating. The reverse voltage experienced would be too high, which is not allowed. 5. There are two ways to adjust the power of the series intermediate frequency furnace: change the DC power supply voltage Ud or change the trigger frequency of the thyristor, that is, change the load power factor cosφ. The power regulation method of parallel inverters can only be changed by changing the DC power supply voltage Ud. Although changing cosφ can also increase the inverter output voltage and power, the allowable adjustment range is small. Tandem intermediate frequency furnace series intermediate frequency furnace purchase necessary guide Today, our Xi'an series intermediate frequency furnace manufacturer will share with you what should pay attention to when purchasing intermediate frequency furnace? When the fasteners are diathermy, when the diameter of the heated workpiece is greater than Φ60mm, intermediate frequency equipment (intermediate frequency furnace, intermediate frequency electric furnace) should be selected. At this time, using a high frequency machine will cause 'burning flow' outside the workpiece and 'black heart' inside. (commonly known as 'unburned'), not only the efficiency of the equipment is greatly reduced, but also the life of the mold is reduced and even the mold is damaged, which increases the cost invisibly, but I don't know the reason. The single-phase input current of the equipment is 120A ~ I input power is 120KVA, and they are collectively referred to as 120 machines. As a result, after buying it, I found out that the real power is only 80KVA. Misunderstanding 3: Only look at the output, not the input. The efficiency and power consumption factors of the intermediate frequency furnace and the intermediate frequency electric furnace are ignored. After the equipment is repurchased, it is found that it is an 'electric tigerFor example, it is also 80 machines, but one has an input power of 80KVA, and the other has an output power of 80KW. However, the working efficiency of the equipment is very different. Although it can also meet the heating requirements, the large power consumption makes users complain. The input power of a device with an output of 80KW is as high as 120KVA. Customers may wish to use the misunderstandings mentioned above as a reference before purchasing. Of course, a more convenient and polite way to buy is to directly choose Jiuli's intermediate frequency furnace equipment, so that you can enjoy high-quality products and services in one step. Series intermediate frequency furnace The above is what our editor from Guangzhou Youzao shared with you about the matters that you should pay attention to when purchasing a series intermediate frequency furnace. I hope the hungry content introduced above can be helpful to you.