Meanwhile, solid-state (or power-transistor) technology, which utilizes transistors to produce radio frequency power, has seen tremendous advancements in recent years, making it the clear choice for RF applications.
Here are seven key ways in which solid-state outperforms vacuum-tube technology:
Unlike vacuum-tubes which often experience failures that prevent your power generator from operating, solid-state generators are incredibly reliable.
According to the US Military Reliability Handbook (MIL-HDBK-217F), high-power vacuum tubes fail 4000 times more often than high power transistors. Although some vacuum tubes do not fail suddenly, every vacuum tube will degrade over time, limiting its useful life to a few years. Once a tube has failed or worn out, the system is shut down until a new tube can be found and the equipment repaired.
Due to the superior reliability of transistors, solid-state generators will have far fewer failures and many more years of trouble-free operation. This will allow your facility to run smoothly, without interruption for years to come.
A solid-state RF generator can convert 95% of the electricity it consumes into radio frequency energy. By comparison, vacuum tube systems, operating under ideal conditions, may convert up to only 70% of the incoming electricity to RF power.
Several factors can reduce the energy efficiency of a vacuum tube generator including properties of the material that is being processed and the operating power level.
Conversely, a solid-state generator is impacted less severely by these factors. A reasonable estimate is that a solid-state generator will consume only half the energy required by a vacuum tube RF generator. For example, a tube system supplying 25kW of RF energy for six hours per day will have an energy consumption of approximately 300 kWh/day. This system will add $10,000 to your electricity bill (at $0.12/kWh) when operated 5 days per week.
A solid-state solution can save $5000/year in this case. The energy efficiency of solid-state RF power generators will reduce your electricity usage, saving your business money.
A solid-state RF generator has a sophisticated digital control system that monitors RF power levels thousands of times per second. It reacts instantly to any change, delivering constant, consistent power throughout the heating process.
Most vacuum tube systems do not monitor RF power and only intermittently regulate DC power or operate completely without regulation. As a result, the process can drift significantly over time, requiring adjustment by operators and resulting in poor product quality, rejects, and waste.
Unlike vacuum-tube generators, which have limited adjustability, solid-state generators can be instantly adjusted from zero to full power. Easy, direct connection to common industrial controls allows for automatically adjusted schedules to be developed and feedback from sensors to adjust or stop the process when needed. Taking advantage of these controllability features can ‘dial in’ your process, resulting in a consistent, high-quality product while reducing rejects and waste.
Vacuum tube systems often consume significant time from operators and support staff. This is due to frequent failures and the need for close monitoring and adjustments. A solid-state solution is ‘set-and-forget,’ delivering consistent performance for many years. This allows staff to focus on other more productive tasks.
Due to its impressive energy efficiency, a solid-state generator has significantly lower installation costs. For example, a 50kW, 95% efficient generator can easily operate on a 100 Amp (480V) service while a tube solution will require a 200A service. Also, a tube generator generates much more waste heat in the building, requiring improvements to cooling systems.
Vacuum-tube generators require DC voltages of 8000 Vdc or higher. These voltages are far more hazardous than the low voltages used with solid-state generators. Also, because vacuum-tube systems are prone to regular failures and may need constant adjustments, operators may take shortcuts and be exposed to the risk of electric shock. With reliable, low voltage solid-state generators, the risk is reduced substantially, resulting in a substantial improvement to workplace safety.
To those familiar with the myriad benefits of solid-state technology, the transistor-based solution is the clear choice to power a RF heating system. Unfortunately, solid-state has historically been too expensive for most facilities, forcing facility managers to settle for the inferior vacuum-tube.