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Analysis of working principle and function of electric heating capacitor
The electric capacitor uses coarsed polypropylene film and high performance liquid (excluding PCB) as composite medium, high purity aluminum as pole plate, porcelain-covered copper screw and cooling water pipe as lead out terminal, aluminum alloy plate as outer shell, and inner water cooling pipe. The shape is mostly rectangular box structure.
 
Intended primarily for use in controllable or adjustable ac power systems with rated voltages up to 3.6kV and frequencies up to 50kHz, specially designed to improve the power factor in induction heating, melting, stirring, or casting devices and similar applications.

Service conditions of electrothermal capacitors
A. Install the device in an indoor environment at an altitude less than 1000m.
 
B. No violent mechanical vibration, harmful gas, steam and explosive dust in the installation site.
 
C. The inlet temperature of cooling water shall not exceed 30℃. For capacitors below 1000kvar, the water flow rate shall not be less than 4L/min, and for capacitors above 1000kVAR, the water flow rate shall not be less than 6L/min.
 
D. Long-term overvoltage (not more than 4 hours IN 24 hours) shall not exceed 1.1UN, and long-term overcurrent (including harmonic current) shall not exceed 1.35in.
 
Electrothermal capacitor structure
RWF and RFM water-cooled all-film electrothermal capacitors are mainly composed of a core and a shell. The core is composed of a number of components equal or unequal) in parallel, and one side of the core element (common plate) is welded with a cooling water pipe; The case is made of steel or brass plate, aluminum plate bending welding box cover with inlet and outlet water pipe and bushing support terminal. The shell is filled with excellent insulating liquid except the core.
 
Electrothermal capacitors are mainly used in induction heating systems to improve power factor or loop characteristics.
 
How electric capacitors work
In a sense, capacitors are a bit like batteries. Although they work in very different ways, both can store electricity. If you've read about how batteries work, you should know that batteries have two electrodes. Inside the cell, chemical reactions cause one electrode to produce electrons and the other to absorb them. A capacitor is much simpler, and it doesn't produce electrons -- it just stores them. In this article, you will learn what a capacitor is and its applications in the electronic field. The difference is that the electric capacitor uses a low melting alloy.

Failure analysis
The principle of intermediate frequency electric furnace: the rectifier inverter of thyristor generates intermediate frequency power supply, which is sent to the furnace coil, and the furnace body (coil) produces intermediate frequency electromagnetic field, so that the metal in the furnace body produces eddy current, and then the eddy current makes the metal produce a lot of heat energy to melt the metal. If electric furnace is also a kind of induction furnace, the working process is as follows: First is through an inverter power supply, the three-phase alternating current rectifier (SCR) into a single phase dc, then the inverter bridge into a 200-8000 hz frequency inverter pulse ac, again through the furnace in the copper coils to form magnetic field, magnetic field make the metal inside the copper coils produce eddy current, eddy current through the heated metal, heat, In order to achieve the purpose of melting metal.
 
If the capacitance of the intermediate frequency furnace burns out, the main reasons are as follows:
 
1. The cathode of the electric heating capacitor is grounded. If the insulation of the electric heating capacitor is poor during the use of the electric furnace, the cathode of the capacitor will be grounded, resulting in the breakdown of the capacitor shell.
 
2. Lack of water, in the long-term use of the INTERMEDIATE frequency furnace, the intermediate frequency furnace may scale in the cooling pipe of the capacitor or the water intake system may enter the debris blockage, resulting in the overheating and burning of the electric capacitor. Therefore, in the process of use, we should pay attention to the flow rate of heating capacitor cooling water. If the flow rate is abnormal, corresponding measures should be taken.
 
3, if the medium frequency voltage is too high, in the long-term use of the medium frequency melting furnace, if the medium frequency voltage is too high, higher than the rated voltage of the electric capacitor (the rated voltage of the electric capacitor is 750V, 1200V and other common specifications), it will cause the over-voltage breakdown of the electric capacitor. If this is the case, you need to lower the intermediate frequency voltage or replace the electrothermal capacitor with a high voltage rating model.

2021-08-18
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