RECOM: Efficient Industrial Power Supplies with Active Power Factor Correction

Figure 1: Phase shift between current and voltage in an inductive load with and without power factor correction. (Source: RECOM)

In industrial applications, inductive loads often dominate, typically caused by motors, transformers, welding equipment, and induction heaters. These loads create a phase shift between current and voltage, resulting in a low power factor (PF). Additionally, distorted, non-sinusoidal current drawn by non-linear loads also leads to a low PF. The power factor of an AC power supply system indicates how efficiently electrical power is drawn from the grid. A PF below 1 means that more apparent power must be supplied than the actual active power required.

However, a low power factor can have significant disadvantages, including:

• Increased energy consumption: More current is required to perform the same amount of work.
• Higher operating costs: Utilities often impose penalty charges on facilities with a low power factor.
• Infrastructure strain: Higher currents necessitate larger cables and transformers, increasing capital expenditure.
• Reduced system reliability: Increased voltage drops, flickering, and overheating of electrical components.

For the efficient transmission of high electrical power, a high power factor is desirable to avoid unnecessary energy losses due to reactive power. An example illustrates this: A 300 W AC/DC switched-mode power supply (SMPS) with a power factor of 0.6 draws 500 VA from the grid. This places a 500 W load on the infrastructure, even though only 300 W are actually usable.

To mitigate these drawbacks, power factor correction (PFC) is employed. Technically, PFC improves the power factor by adding inductive or capacitive elements to reduce the phase shift and minimize harmonic distortions.

There are two main methods: Passive PFC uses capacitors or inductors for fixed compensation. In contrast, active PFC uses electronic circuits to dynamically shape the current waveform, resulting in higher efficiency and adaptability. Active PFC is especially effective in applications with variable loads, as it continuously optimizes the power factor. It is commonly used in modern switched-mode power supplies.

How does RECOM’s RACPRO1 series boost efficiency and reliability in industrial applications?

The RACPRO1 series from RECOM features integrated active power factor correction (PFC). The models RACPRO1-T240, -T480, and -T960 provide 240 W, 480 W, and 960 W respectively, making them suitable for industrial automation as well as mission-critical applications.

Their advantages include:

• High power factor: Typically >0.9, which reduces energy consumption and increases efficiency.
• Reduced losses: Less reactive power means lower losses and reduced current consumption.
• Lower installation effort: The reduced current demand allows for the use of smaller cable cross-sections and fuses. This leads to lower installation costs and a more efficient electrical system.
• Compliance with industry standards: The products meet the requirements of IEC 61000-3-2 and other international standards, making them suitable for global applications.
• Compact and reliable DIN-rail design: The compact power supplies can be easily installed in control panels with limited space. A high Mean Time Between Failures (MTBF) also ensures long-term reliability, even in demanding environments.

Integrating power compensation circuits—especially through active PFC—is crucial for the efficiency and reliability of industrial switched-mode power supplies. With the RACPRO1 series, RECOM offers an effective solution to improve the power factor, reduce operating costs, and extend the service life of equipment.

Figure 1: Phase shift between current and voltage in an inductive load with and without power factor correction. (Source: RECOM)