# Supply Systems of Non-Thermal Plasma Reactors. Construction Review with Examples of Applications
## 3 Transformer Power Supply Systems for Plasma Reactors
### A Five-Column Transformer as a Power Supply for a GAD Plasma Reactor  
A modification of the integrated system is the use of a five-column transformer in the plasma reactor supply system. In typical designs of five-column transformers, magnetic flux closing through external columns is not in use. It was proposed to use the energy of the external columns' fluxes in a three-phase five-column transformer. The idea of this solution is presented in Figure 6. The voltage induced in the windings of the external columns can be used to power the ignition system of the plasma  
Figure 4: IPSS with artificial neutral point from three capacitors connected in star—N2 artificial neutral point, N1 and n—neutral points according to primary and secondary side of transformers Tr1, Tr2, and Tr3 connected in star [43]. Figure 5: (a) IPSS for six electrode; (b) nine electrode GAD reactor (TrZ—ignition transformer) [5; 43]. reactor. In this way, the energy of the magnetic flux closing in these columns will be used to ionize the inter-electrode spaces of the GAD reactor. Tests conducted on a 11 kVA laboratory model confirmed the validity of the idea of using a five-column transformer to power 3-electrode GAD reactors. In particular, they proved that it is possible to use the energy of magnetic fluxes closing through the outer columns of the transformer to ignite the GAD. Figure 7a presents the courses of ignition voltage and (b) between electrodes voltage of GAD reactor in argon as a processing gas [44; 47]. The method of the reactor ignition system designing does not impose restrictions and it is possible to supply PRs without separate ignition circuits as well as with two-electrode and single-electrode ignition systems. In all analyzed cases, the tested five-column transformer design performs the basic functions of the power supply, i.e.,: enables initial ionization of inter-electrode spaces, ignition of the discharge  
Figure 6: A 5-column transformer with external wound columns and a magnetic circuit made of wound cores; (**a**) windings connection—external column windings connected in series; (**b**) arrangement of working and ignition coils on wound cores, 1/2—concentrically wound primary and secondary windings, 3—windings of external columns designed for supplying ignition systems of GAD plasma reactor [23; 44]. Figure 7: (**a**) Ignition voltage \(\mathrm{U_{ign}}\) waveform (distance between ignition electrodes 5 mm) when supplied from external windings connected in series of the five-column transformer (**b**) voltage \(\mathrm{U_{GAD}}\) between electrodes of GAD reactor in argon, at a the primary voltage of 90V, [44]. and its maintenance during the PR operation cycle, limiting the short-circuit current while ensuring the correct current value for plasma processes. As an example of GAD plasma application, an installation of the exhaust gas purification from paint shop is presented [5; 53]. GAD plasma reactor construction shown in Figure 8a consisted of one central ignition electrode and three working electrodes placed around the center of the discharge chamber in 2\(\pi\)/3 radians distance from each other. Technical specification of GAD reactor is given in Table 1.  
Plasma burn-up of gases emitted from factory was tested using pilot-plant set-up installed in foundry's production line. Gases polluted during painting and drying of foundry molds were mixed with hot air and emitted to the atmosphere via three chimneys. Average flow rate of gas was 2000 m\({}^{3}\)/h, temperature at the outlet was 150 degree centigrade. Main pollutants were heptane, toluene, xylene, butanol, serpentine, and ethyl acetate. In Table 2, laboratory scale experimental results are presented for propane and butane as pollutants. The ratio of pollutants varied in dependence on the used paint. Molds' drying system with inlets (I), outlets (O), and GAD PR placed on one of the output chimneys is presented in Figure 8b.