The new alternatives in power conversion

However, while the method of conversion allows a heater to operate at a given set temperature, it receives the full voltage when turned on, which can cause damage over time in some cases. Other solutions, such as phase-angle controllers and DC power supplies also have their own setbacks, making power conversion a tough task. In this article, Stan Breitlow, chief system designer at industrial temperature controller manufacturer Watlow, discusses the new alternative in power conversion.

The necessity of power conversion

The goal with a heater is not to attain a given DC current, but to maintain a given temperature, which is done using a switching device that turns the power on and off rapidly. Usually, this kind of switching or cycling is not an issue. But in some cases when heaters are small, have ceramic components, or where control of multiple heaters is needed, it is not ideal to have the device on with full voltage, let alone have it switching between states. For example, this can happen when precise heating is needed in medical devices, or rapid heating is needed to test microchips in the semiconductor industry.

The issue becomes worse when constructing devices for an international market. Heaters often have very specific voltage requirements, but the power sources can vary from country to country. In today’s global economy, there is a great need to normalise this power for use with heaters built for the voltage requirements of any country. In short, power conversion is an old idea, but current technologies in the market are not well suited for some applications.

The problem with power conversion

Power conversion is essential for any heater, whether in an in-home medical device or a large-scale industrial process. But as heaters become smaller and more intricate, more attention must be paid to their power supply. It’s important to be mindful that there are four types of cases where inadequate power conversion can lead to problems.

Firstly, fragile heaters become easily damaged. Switching a higher-voltage power source on and off creates wear and tear on devices. As this happens, smaller, more fragile heaters are more likely to fail over time.

Popular ceramic heaters are often made with molybdenum, which expands and contracts at the same rate as the ceramic. But molybdenum changes resistance with temperature, which means hitting a ceramic-molybdenum heater with a high voltage when it is cold can cause the device to crack or burst — which can become an expensive problem for manufacturers.

Additionally, available voltage varies around the world. For instance, a heater that is embedded in an at-home medical device and distributed globally, must be able to work safely whether connected to a 100-volt power source in Japan or a 240-volt power source in Germany. With appropriate power conversion, a single heater can be designed for the lowest voltage expected as incoming voltage can be brought down from whatever the local standard happens to be.

New power conversion technology

Power conversion is commonly achieved through phase-angle controllers, transformers and power supplies. But as we have seen, these solutions can either damage heaters, or take up large amounts of space or make it incredibly hard to measure and control the power flow. Watlow’s power conversion technology solves these issues by providing the ability to bring voltage up or down smoothly without having to introduce a bulky power supply.

Watlow temperature controllers, such as POWERGLIDE, are capable of modulating the amplitude of the output voltage, allowing the voltage to step down from 208 volts to as low as 20 volts.

Lowering the voltage in this way is a great way to drive low-impedance heaters. It can reduce the power distribution rating with smaller fuses and wires, which saves money and space. It can also protect ceramic heaters from breaking. Watlow’s power conversion technology also achieves high power quality without the high cost and added space of a DC power supply.

Power conversion is an essential element of many heating applications. Yet most current power conversion technology is not well suited to cases where heaters are fragile, have ceramic components, or have to ensure safe operation across the globe. No longer do devices have to be engineered around power quality issues. Instead, smooth, stable power changes are possible across a huge variety of outputs, and noise is reduced drastically.