The traditional source of alternating current for welding is a welding transformer. DC power supply is a rectifier, which is designed on the basis of the transformer and the semiconductor rectifier. Widespread and inverter power sources, which are used for welding both alternating and direct current. Intermediate position between traditional rectifiers and inverters occupy sources, which include a simple 50-Hz welding rectifier, control current is a key regulator of a semiconductor operating at high frequency. Technological capabilities of the sources Supply by external volt-ampere characteristics. Static characteristic of the power supply is a plot of output voltage of the load current at constant voltage mains in the steady state. By type of static external characteristics of current sources can be divided into sources with the incident (PVC) "cool" and "gentle" or rigid (ZHVH) external characteristics.
Sources with external characteristics of the two species are said to be universal. Requirements to view the external characteristics are determined by the welding process parameters as the type of electrode (consumable without melting), the nature of the environment in which the welding (open arc, submerged arc, gas shielded), degree of mechanization (hand, machine, automatic welding) method of regulating the mode of arc (self-regulation, the automatic regulate voltage arcs). For example, for manual arc welding with coated stick electrodes, TIG welding TIG, submerged arc welding machines for the regulation of feed speed electrode wire as a function of the arc voltage sources are used in PVC. PVC power supply operates in control of welding current. Welding current can be adjusted smoothly and the specified range or steps.
On process conditions using sliding cascade control when two or more levels of regulation combined with infinitely variable within each level. Control of welding current for PVC performed at approximately constant load voltage. Each type of welding corresponds to a certain slope steepness PVC. For example, the steeper the characteristics used for TIG welding more gentle – for submerged arc welding. Length of arc in the welding process for PVC is manually adjusted or regulatory system in the welding machine. Mechanized welding in the environment and the C02 in automatic welding under flux at constant speed wire feed power supply is used with ZHVH. In this case, power supply acts as a regulator operating voltage, which is regulated within the prescribed limits, subject to specified value of the welding current. Voltage regulation at ZHVH may be gradual, stepwise and mixed. The value of the welding current is determined by the speed of wire feed and power supply sets the voltage arc and provides a self-arc length. The duration of the power supply should not be prolonged in order to avoid unacceptable heat insulation of the power.