Transformer maintenance of welding machine

In many industrial equipment are used, in these equipment, frequency converter is often a very important component, in order to ensure that the equipment can work for a long time and stable, we have to pay attention to the correct use and normal maintenance of frequency converter .

 If you want to use the frequency converter correctly, you must correctly understand the working principle of the frequency converter and seriously consider the problem of heat dissipation of the frequency converter.  The failure rate of frequency converter increases exponentially with the increase of temperature.  Service life decreases exponentially with increasing temperature.  Ambient temperature rise 10 degrees, frequency converter service life half.  Therefore, we should pay attention to the problem of heat dissipation!  When the frequency converter is working, the current flowing through the frequency converter is very large, and the heat generated by the frequency converter is also very large, so the impact of its heating can not be ignored.  

Usually, the frequency converter is installed in the control cabinet.  We need to know the calorific value of a frequency converter, which can be estimated by the following formula:  The approximate value of caloric value = frequency converter capacity (kW) ×55 [W] Here, if the frequency converter capacity is based on constant torque load (over current capacity 150% * 60s), if the frequency converter has a DC reactor or an AC reactor, and is also in the cabinet, then the caloric value will be larger.  It is better to install the reactor on the side of the frequency converter or above the measurement.  At this time, it can be estimated that the frequency converter capacity (KW) ×60 [W] because the hardware of each frequency converter manufacturer is similar, so the above formula can be used for the products of each brand.  Note: if there is a brake resistor, because the heat dissipation of the brake resistor is very large, so the best installation location is better separated from the frequency converter, such as installed on the cabinet or next to the cabinet.  So, how to pick can reduce the heat in the control cabinet?  When the frequency converter is installed in the control cabinet, the heating value of the frequency converter should be considered.  The size of the cabinet should be appropriately increased according to the increase in the heat value generated in the cabinet.  Therefore, in order to minimize the size of the control cabinet, it is necessary to reduce the heat value generated in the cabinet as much as possible.  If the radiator part of the frequency converter is placed outside the control cabinet when the frequency converter is installed, 70% of the heat of the frequency converter will be released to the outside of the control cabinet.  Due to the large capacity frequency converter has a large amount of heat, so the large capacity frequency converter is more effective.  Can also be separated from the body and the radiator with the isolation plate, so that the heat dissipation of the radiator does not affect the frequency converter body.  That works pretty well, too.  Inverter heat dissipation design is based on vertical installation, horizontal heat dissipation will get worse!  About the cooling fan general power slightly larger frequency converter, with cooling fan.  At the same time, it is also recommended to install a cooling fan on the air outlet of the control cabinet.  Filter screen should be added to the air inlet to prevent dust from entering the control cabinet.  Note that the fans on the control cabinet and frequency converter are needed and cannot be replaced by anyone.  

In addition, the heat dissipation of the frequency converter should pay attention to the following two issues:  

(1) At an altitude higher than 1000m, the cooling air volume of the cabinet should be increased to improve the cooling effect because the air density is reduced.  Theoretically, the frequency converter should also consider reducing capacity, 1000m per -5%.  But because of the fact that the load capacity and heat dissipation capacity of the frequency converter are generally larger than the actual use of the design, it also depends on the specific application.  For example, in a place of 1500 meters, but the periodic load, such as the elevator, is not necessary to reduce the capacity.    

(2) Switch frequency: the heat of the frequency converter is mainly from IGBT, and the heat of IGBT is concentrated at the moment of opening and closing.  Therefore, when the switching frequency is high, the heat generated by the natural frequency converter becomes larger.  Some manufacturers claim to reduce the switch frequency can expand capacity, is this truth.  According to the temperature of the cut rolled pieces, there are hot shear and cold shear.  

According to the relative position of the two blades, there are also parallel blades, oblique blades and disc blades.  

According to the structure form and blade movement mode of flying shear, it can be divided into many kinds, and with the development of modern high-speed rolling mill, new flying shear constantly appear, widely used are: disc flying shear, rotary rotary flying shear, pendulum flying shear, horizontal flying shear and so on.