## 2 GlidArc Plasma Reactor  
Plasma reactors are technological devices that convert working gas into plasma by using electricity. The source of the plasma is an electric arc in the gas. The formation of an arc discharge is connected with the flow of current in the gas [5,15,16,17,18,19,20]. Figure 1: Electromagnetic compatibility—the idea of interaction. Arc discharges are a non-linear and asymmetrical load for the supply system. Dynamically changing transient and short-circuit phenomena of the plasma producing discharges are the source of electromagnetic disturbances [2; 3; 21; 22]. Electric arc discharge is related to the flowing current in the gas. The discharge depends on ionisation processes and its character determines the value of current flowing between electrodes. The voltage applied to the electrodes is also important. One of the types of plasma reactors is a reactor with arc discharge gliding along electrodes under the technological name GlidArc. Figure 2 presents the installation of a three-phase GlidArc plasma reactor tested in the Department's laboratory. Reactors of this type are used mainly in the neutralisation of toxic gases, such as SOx and NOx or in other technologies [17; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28]. The quasi-arc discharge created in them is a source of non-thermal plasma filling part of the discharge chamber space. The source of plasma and the method of energy supply to it is the forced flow of electric current in gas in the form of an electric arc [15; 16; 18]. The main feature of GlidArc reactors is the ability to generate non-thermal plasma directly in the contaminated gas, at atmospheric pressure and in the conditions in which the exhaust gases are emitted into the atmosphere. The idea of operating a reactor with a so-called gliding discharge is as follows. The treated gas is introduced axially, at a certain speed (volume flow), between the working electrodes. The device under test consists of three knife-shaped working electrodes, after which, under the influence of forced gas flow and electrodynamic forces, an expansive electrical discharge \"glides\". The non-thermal plasma generated in this way fills a significant part of the discharge chamber space [5; 15; 18]. The voltage value on the electrodes needed to ignite the arc is 1-20 kV, but to sustain it the voltage is many times lower. The arc discharge begins in the place where the distance between the electrodes is the smallest (several millimeters). The plasma of the gliding arc discharge, like other arc discharges, can be generated at DC, AC and pulse voltages. Industrial plasma reactors with gliding arc discharge are constructed as two-, three- and multi-electrodes and often have an additional ignition electrode [2; 3; 5; 15; 16]. The development of an arc discharge and its duration depends on several factors: the chemical composition of the gas, the temperature in the discharge chamber, the electrical parameters of the power supply system and the dimensions and geometry of the electrodes. An important element of the power supply is therefore the system of working electrodes. The power supply of the three-phase plasma reactor used in the tests (Figure 2) is a system consisting of three single-phase transformers shown in the photograph. The transformers are connected to a star-star three-phase system with a neutral conductor. These transformers provide a maximum  
Figure 2: Laboratory installation of a 3-phase GlidArc plasma reactor. sinusoidal power supply of 1.6 kV. This voltage does not guarantee arc ignition. Therefore, the reactor has ignition electrodes powered by a high voltage circuit--10 kV from ignition transformer - model Resinblock 2000 (F.A.R.T. SRL, PREGANZIOL, Italia)). The main power supply is regulated by the autotransformer - model HGT 400/8 (Metrel d.d., Horjul, Slovenia), the ignition system is regulated by 1-phase autotransformer - model SRV-5 CAP: 500 VA (Chuan Hsin Electric Works Ltd., Taipei, Taiwan).