RF Systems

At Delphius we design RF systems around the product to be heated. In this way, the full benefit of dielectric heating can be harnessed. Each application has specific requirements on the oven size and type. We have developed equipment for clients in the chemical, pharmaceutical, food, timber, minerals and manufacturing industries.

300kW RF Generator

Delphius designed and built this system to deliver 300kW of RF power at a fixed frequency of 13.56MHz into material in order to dry it in the shortest amount of time.

The RF side of this system consists of a high power RF vacuum tube that is used as a class C amplifier. It is driven by our 2kW RF generator which oscillates at 13.56MHz. The 12V, 660A filament supply and the variable 800V, 4A switch mode power supplies for the grids were developed in-house.

Generator specifications:

  • RF circuit configuration Oscillator with RF power amplifier
  • RF output power 300kW
  • DC supply voltage 15kV, 29A DC
  • RF frequency 13.56MHz (crystal based)
  • RF output 9" rigid coaxial line
  • RF output impedance 50 ohm
  • Load matching Impedance matching network with adjustable capacitors

A PLC is used to control the RF generator.

Features include:

  • Monitoring temperatures;
  • Monitoring coolant flow and levels;
  • Controlling output power and efficiency;
  • Controlling all power supplies;
  • Monitoring interlocks.

A status panel indicates important parameters for speedy fault finding.

The system also includes an automatic matching network to ensure maximum power is delivered to the load. This is done by measuring the forward and reflected power of the output and tuning the network to ensure that the energy is delivered to the material.

50kW RF Generator Upgrade

This system was originally a free oscillating system but was upgraded by us to a fixed frequency of 13.56MHz at 50kW RF power into a 50ohm load.

Upgrades included:

  • Replacing electro-mechanical control with PLC control;
  • Replacing obsolete components with commercially available ones;
  • Frequency stability;
  • Improve efficiency.

Generator specifications:

  • RF output power Adjustable from 5 to 50kW
  • DC to RF efficiency 85%
  • RF frequency 13.56MHz (crystal based)
  • RF output 2" rigid coaxial line
  • Cooling Internal demin water system
  • Internal air circulation system
  • Interface External PLC

RF Tunnel

The tunnel has a 500mm wide conveyor, with a 1.5m heating zone. Infrared sensors monitor the temperature of the product entering and exiting the tunnel. Two, 10kW RF generators supply the RF power to the two electrode systems, each with its automatic impedance matching unit. This allows accurate moisture profiling to be done.

This system is used for process optimisation and parameters such as conveyor speed (exposure time), power levels, airflow and temperature will be adjusted to obtain optimum performance. Energy input is recorded to calculate specific energy consumption.