Abstract: An assembly according to the invention includes two pairs of relays, such as SSR semiconductor relays. The relays of each pair operate with the opposite direct current potentials. Direct current with the voltage of 220 V to 400 V as well as control lines are connected to the clamps of the controlled relays. The operation of the relays is controlled by means of a controller, such as a PLC programmable controller. The relays are connected to the first electrode clamp, and the other relays to the second electrode clamp. The assembly operates in such a way that the PLC controller activates the relays from the line, which simultaneously activate the flow of the direct current with the voltage of 220 V to 400 V and mutually opposite polarity. As a result of this, a difference of potentials appears on the electrode clamps.