# Supply Systems of Non-Thermal Plasma Reactors. Construction Review with Examples of Applications
## 3 Transformer Power Supply Systems for Plasma Reactors
### Integrated Power Supply Systems  
In the basic solution of the IPSS, three single-phase power transformers (Tr W), with magnetic circuits ensuring free return paths for higher harmonics of the magnetic flux, are fed from a symmetrical three-phase network [43; 47]. The primary windings of the transformers are connected in a star (Y), while the secondary windings, depending on the type of non-thermal plasma reactor and the number of electrodes, can be connected in an open triangle (d) for DBD reactor--Figure 1a or 2--electrode GlidArc and in a star (y) when fed with a three- and multi-electrode GlidArc--Figure 1b. Idea of the IPSS is based on the non-linearity of the power transformers' cores. IPSS for DBD reactor is the well-known solution of the magnetic frequency tripler (mf3). Output voltage of the supplier has the tripled frequency of mains (150/180 Hz), therefore the DBD plasma reactor running at three times increased frequency can be supplied at more than 30% lower voltage than at 50/60 Hz having the same active power P [43]. Moreover, the voltage to the DBD plasma reactor can be easily adjusted (VR) by the impedance connected in series in the neutral conductor of the primary side of the PS, between the PEN and N terminals. In this way we get increase of frequency and voltage as well as its regulation in the one power supply of DBD reactor. In addition, reactive power compensation required in other transformer systems because of increased magnetic flux density is not necessary for the capacitive receiver that is the DBD reactor. IPSS of GAD Multielectrode Plasma Reactors  
Plasma-chemical reactions generated by the GAD take place directly in the polluted gas, therefore this kind of non-thermal plasma reactors have found applications in the treatment of flue gases emitted by industrial processes of coal and biomass combustion (SO\({}_{2}\), NO\({}_{\rm x}\) removing), painting and varnishing (VOC abatement), wastes utilization [47; 52]. In all these processes non-thermal plasma should be generated in relatively large volume of chamber, with dimensions in the range of centimeters or even meters, unlike dimensions of DBD reactors discharge gaps of millimeters range. Multielectrode and multistage GAD plasma reactors are used in these applications to increase the time of the penetration of polluted gas by the non-thermal plasma, what is achieved by the connection of the discharge chambers in series with the gas flow, or in parallel, to divide the polluted gas stream into smaller streams [5]. Plasma reactors with GAD have different requirements for the power supply system than reactors with DBD. The ignition of the discharge should be realized at a voltage of several kilovolts (depending on the distance between the working electrodes), while the voltage on the discharge after ignition amounts to several hundred volts. This disproportion of ignition and stable operation voltages as well as the strong non-linearity of the conductance of the discharge creates a difficult task for the power supply system, which must have the properties of both a high-voltage ignition system and a system that delivers the power to the discharge chamber and follows the rapid time changes of the non-linear current-voltage characteristics of the GAD. The name \"integrated\" was introduced by the authors with the idea of this system [43; 48; 49; 50; 51], for the following reasons, fundamental for the GAD plasma reactor operation: (1) Integration of the ignition function in the power supply, (2) sustaining discharge current at each passage through zero, and (3) ability to limit short-circuit current of PSS. IPSS for the three-electrode GAD PR consists of four transformers--three power and one ignition--Figure 1b. Primary and secondary windings of the power transformers are connected in a star, with the secondary winding terminals connected to the plasma reactor electrodes WE1, WE2 and W3.