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How to choose a welding inverter

How to choose a welding inverter

Any house master periodically required to attach the hinges to the gate, the old car body repair , weld metal pipe , etc. , for which he needs to use electric welding . Many people in such cases, hire professionals . However , there are those who prefer to independently perform all these works . After all, if you do yourself, then no one is hung, no one is paid and , besides , there is always guaranteed a responsible attitude to work .

The first thing a supporter of “independent path” – gets the welding machine . However, these units are not cheap , so it is necessary to acquire them wisely , taking into account the present and future needs and opportunities. To date, there are several types of welding equipment : welding transformers, welding rectifiers and welding inverters . The latter type are addressed in this article .

Welding inverter – a modern device DC , whose work is based on the phase shift of the voltage ( inversion ) with cascade increasing the power and frequency . This conversion is carried out twice. At the entrance to a standard AC mains frequency of 50 Hz is applied to the rectifier ( diode) that transmits only half-time. The rectified current smoothing filter , as a result it is inverted ( inverter converts ) to AC , but has a higher frequency . At the moment, there are technologies transform frequencies up to 100 kHz (which is an important technical solution to achieve significant welding inverters , compared to other welders, advantages). The welding inverter requires almost twice less power than any other welder .

At the moment, MMA inverters are available in two technologies : MOSFET ( powerful insulated gate field-effect transistor ), the IGBT ( bipolar transistors with insulated gate ) . The main difference between them – the different switching current . Furthermore, for the inverter , for example, 160A need 2-3 IGBT- transistor and MOSFET – 10-12 pieces.

The scheme does not allow a MOSFET device on a single board , basically they are collected on three boards. All devices IGBT always go with one card. Accordingly , the devices manufactured by technology IGBT, smaller , lighter and more maintainable for other comparable parameters. In addition, due to the smaller number of transistors and circuit boards ( in comparison to devices MOSFET) IGBT- unit price is usually lower than the price of MOSFET- machine.

The main disadvantages with respect to the MOSFET IGBT – this is the worst heat transfer, joining the three boards , cascade failure of the transistors in the failure of even one of them, the lower efficiency . In other words , IGBT – a new, modern technology in comparison with the MOSFET. Although once it is necessary to note that there is still a powerful industrial inverters are collected only on technology MOSFET. In addition , MOSFET – a reliable , unlike IGBT, years proven technology . Externally devices IGBT MOSFET devices are different from the vertical position of power connectors ( with MOSFET they are usually placed horizontally ) .

Define what types of welding inverters are . Separation equipment for household , professional and industrial inverters are usually made from calculating the average amount of time during which the uninterrupted operation of the welding is possible . Inverter welding equipment is lighter and smaller transformers. Each welding inverter equipped with protection that aligns surges in the range of 10-15 % to 20-25 % of household and industrial devices. Inverter technology is used for TIG , MMA welding, plasma cutting, and in a semi-automatic .

Types of welding inverters

1. Household welding inverter

Household welding inverter is designed for use in a domestic environment ( in the garage , cottage , etc.). Mode – short , designed for continuous operation for up to half an hour. Operating current consumer unit up to 200 A. That is, he is able to perform a small amount of work , or any odd jobs . At the price of inverter welding machine affects the class , the circuit assembly and its quality, as well as the quality of components .

These devices are compact forms , light weight ( 3.10 kg) , almost entirely independent of the input voltage . The advantage of such a device is portability , which allows to use it to perform installation and repair work is stationary or in the field. The loss of electricity using domestic inverter reduced several times, and the efficiency reaches 85-90 %. For example, the electrode diameter of 3 mm, it consumes no 8 kW as a conventional transformer , and about 2.5 kW – 3 kW. In addition, if the transformer is typically half the power expended in heating the iron to ” neutralize ” the core and magnetic fields , etc. , the inverter power consumption virtually all ” outputs ” in the arc. An important advantage of the inverter is the function of smooth adjustment of the welding current ( 15-20 A). In addition, to improve the comfort and quality of welding inverters are equipped with household circuits stabilize , enhance the protection against power surges , igniting the arc. Inverters have a high open-circuit voltage (within 85-90 C).

When buying a welder should not be afraid of the concept of ” home .” Terms such as industrial, professional and consumer inverter are not technically unified . Leading manufacturers , classifying their products , usually adhere to the following rules : Marking the “consumer ” corresponds to the continuous operation of the equipment for 15-30 minutes followed by a break of about 60 minutes , “professional” unit assumes an 8- hour cycle of operation, and “industrial” can work around the clock with short breaks technological . All other characteristics of household , professional and industrial equipment are essentially the same . In other words, due to its voltage stability and calm steady arc , any inverter same quality seam weld penetration . The difference will be the length of only weld made per unit time. Naturally, an inverter that it will at home . In addition , it is logical that the household inverter is not available high power and does not constitute perform some specific tasks .

In addition, welding inverter with built-in digital microprocessor almost “think ” for the welder, constantly analyzing the processes taking place on the arc. May have the following set of useful programs :

disabling the arc voltage in a short circuit electrode on the workpiece (eg, a function «anti sticking»), whereby there is no heating system and adhesion (” primorazhivaniya “) electrode ;
with the correct ( light touch ), the excitation of the arc , the device generates an additional current pulse (the function «hot start»);
a small and unavoidable in the process of local short-circuit , the inverter produces a series of short, high-power current pulses that destroy the bridge of the liquid metal (the function «arc force»), which is particularly important at electric short arc .

2 . Professional welding inverter

Professional welding inverter has a power level of 200 A, which makes it possible to create it a good stock for long and confident welding. However, this is not true for all inverters in the control panel which indicated 200 A. Use of professional welding machines weighing up to five kilograms is not recommended. The optimum weight of the machine should be 8 – 10 kg . The dimensions of the inverter and the internal layout provides good cooling fan built-in all its elements. It is important that during operation in the power supply is not less than 220 , and the electrodes were dried .

The devices are used in the repair of communications, when mounted in housing , garages , workshops and other professional inverter is commonly used for commercial purposes. Requirements for high quality equipment . Terms of use – hard . Mode – continuous.

3 . Industrial welding inverter

Industrial welding inverter assumes greater number of different welding techniques . Usually it is difficult welding of steel structures, installation of pipelines , construction of infrastructure and industrial projects. Mode of operation of such equipment – continuous ( shift work ) . Requirements for the quality of work – high . The volume of work – great .

Different models of industrial inverters depending on the power and current characteristics have their own characteristics . There inverters for arc welding of metal in an argon environment using a non-consumable tungsten electrode (TIG- welding) . This inverter is able to connect any quality parts and components .

Industrial welding inverter arc welding ( MMA welding) involves the use of piece of coated electrodes .

Other useful tips for choosing the welding inverter

The main enemies of electronics – it is moisture and dust , especially metal dust . Therefore, do not include the unit in a dusty environment , and not allowed to work , ” grinder ” in the vicinity of the included inverter.
During the rain all welding work should be stopped.
When you purchase an inverter ask the seller :

about really its power consumption ;
how he is able to work electrode ;
What is the duration of the devices in welding electrode of interest to you ;
a load factor of the device.