Power converter unit (1,1') capable to convert an electrical input power into a bipolar output power and to deliver this output power to at least two independent plasma processing chambers (9a, 9b.. 9n), the unit (1,1') comprising: - one power input port for connection to an electrical power delivering grid, - at least two, preferably more than two, power output ports (3a, 3b,.. 3n) each for connection to one of the plasma process chambers (9a, 9b,... 9n), - switching means (8a, 8b,... 8n) associated with the at least two, preferably more than two, power outputs, - a control device configured to control the unit (1,1') to deliver the bipolar output power to the power output ports (3a, 3b,.. 3n), using control parameters of at least one of: power, voltage, current, excitation frequency, or threshold for protective measures, characterized in that the control device comprises a virtual power supply (24a, 24b,.. 24n) for every output port (3a, 3b,.. 3n), every virtual power supply (24a, 24b,.. 24n) comprising a separate complete set of all fixed and time varying parameters and internal states associated with the operation of every individual output port (3a, 3b,.. 3n), wherein the control device is configured to activate the switching means (8a, 8b,... 8n) from a closed status into an open status only when the absolute value of current through the switching means (8a, 8b, 8c) is lower than one ampere, preferably zero, and/or wherein the control device is configured to activate the switching means (8a, 8b,... 8n) from an open status into a closed status only when the absolute value of voltage along the open switching means (8a, 8b,...8n) is lower than 20 volts, preferably zero. - one power input port for connection to an electrical power delivering grid, - at least two, preferably more than two, power output ports (3a, 3b,.. 3n) each for connection to one of the plasma process chambers (9a, 9b,... 9n), - switching means (8a, 8b,... 8n) associated with the at least two, preferably more than two, power outputs, - a control device configured to control the unit (1,1') to deliver the bipolar output power to the power output ports (3a, 3b,.. 3n), using control parameters of at least one of: power, voltage, current, excitation frequency, or threshold for protective measures, characterized in that the control device comprises a virtual power supply (24a, 24b,.. 24n) for every output port (3a, 3b,.. 3n), every virtual power supply (24a, 24b,.. 24n) comprising a separate complete set of all fixed and time varying parameters and internal states associated with the operation of every individual output port (3a, 3b,.. 3n), wherein the control device is configured to activate the switching means (8a, 8b,... 8n) from a closed status into an open status only when the absolute value of current through the switching means (8a, 8b, 8c) is lower than one ampere, preferably zero, and/or wherein the control device is configured to activate the switching means (8a, 8b,... 8n) from an open status into a closed status only when the absolute value of voltage along the open switching means (8a, 8b,...8n) is lower than 20 volts, preferably zero. power, voltage, current, excitation frequency, or threshold for protective measures, characterized in that the control device comprises a virtual power supply (24a, 24b,.. 24n) for every output port (3a, 3b,.. 3n), every virtual power supply (24a, 24b,.. 24n) comprising a separate complete set of all fixed and time varying parameters and internal states associated with the operation of every individual output port (3a, 3b,.. 3n), wherein the control device is configured to activate the switching means (8a, 8b,... 8n) from a closed status into an open status only when the absolute value of current through the switching means (8a, 8b, 8c) is lower than one ampere, preferably zero, and/or wherein the control device is configured to activate the switching means (8a, 8b,... 8n) from an open status into a closed status only when the absolute value of voltage along the open switching means (8a, 8b,...8n) is lower than 20 volts, preferably zero.