Luoyang Judian Metal Hot Processing Equipment Co., LTD is mainly engaged in the manufacture of complete sets of equipment in the metal thermal processing industry and the integration of the entire production line.
The main advantage of this system is that it does not require frequency conversion. Since no rotating mechanism is required and no complex electronic equipment is required, power losses are reduced, the system is greatly simplified, operation is simple, and the switchgear, power factor compensation capacitors, control circuits, etc.
can be selected from standard ranges. Secondly, radiation losses, heating by scattered magnetic fields, and useless high-frequency induction currents can be ignored Industrial frequency furnace sales.
Industrial frequency furnace
The investment cost of the basic equipment is usually lower than that of medium-frequency or radio-frequency devices. From the application point of view, industrial frequency heating, or mainly heating with a frequency of 50/60 Hz, is mainly used for penetration heating.
Industrial frequency furnace sales
Since most penetration heating requires maximum temperature uniformity, it is more appropriate to use industrial frequency than higher frequencies. We have seen this in this chapter. The formula shows that the lowest frequency can achieve the greatest current penetration depth, so industrial frequency heating is widely used in melting furnaces.
The basic disadvantage of low-frequency heating (especially heating with 50/60 Hz) is that for a certain workpiece shape and inductor magnetic field strength, its input power decreases. The input power varies directly with the frequency.
This disadvantage is often fully compensated by the factor of temperature uniformity, since it takes only a short time to homogenize the temperature by absorbing heat from the surface. Despite the low surface power density values, the workpiece sizes are large, with bar diameters often reaching 250-350 mm, sheet sections up to 2 m x 30 mm and lengths up to 10 m.
Therefore, high inductor and system powers are required. A single inductor can have a power of several megawatts and the system installed power can reach more than 200 megawatts. Due to the high power, balanced three-phase systems are almost always used.
The inductors can be designed as three-phase inductors or as multiples of three single-phase inductors with equal loads. Generally speaking, most non-ferrous metals are heated through the entire body with a single induction coil heater as shown.
When the inductor is filled with the workpiece, the load of these three-phase inductors is quite balanced. If the inductor is only partially filled with the workpiece, one phase will become unbalanced. Therefore, it is best to configure the neutral line in the supply line.
This neutral line can lead to excess current. Another alternative is the phase-balanced system discussed in the article. Most systems use a continuous passage of the workpiece through one or more inductor coils, but integral heating systems are also used.
Medium frequency heating is sometimes used to achieve the higher temperatures above the Curie point required for heating steel, and in such dual frequency systems the number of 50/60 Hz inductors is such that each inductor can be single-phase, thus achieving a good balance of the three-phase load of the power supply.
Three single-phase low-power systems can be loaded onto the three-phase power supply. The article shows the main parts of a typical power frequency system.
In order to match the low-impedance, low-voltage inductor with the high-voltage power supply, a transformer is generally configured. In order to match the changes in the inductor operation and power control, the primary coil of the transformer generally has several taps.
These taps are in an open circuit state. In addition to changing the speed of the workpiece or turning the power on and off (or pulsating the power) with the help of temperature/contactors for control, the tapping method is the typical matching and control method.
This method is generally used for heating non-ferrous metals piece by piece, during which the load changes significantly. Because current and voltage exist when loaded, the tap must be changed after the load is removed.
Sometimes the inductor is operated with a low voltage (such as 230/440 volts), so the transformer can be omitted. On these devices, the only control method is to control the heating time, that is, the speed at which the workpiece passes.
Although limited power control is a disadvantage of power frequency heating systems, this is not as important as in high frequency heating systems. Because at low frequencies, the heating time is usually much longer.
