Power Factor Correction refers to a particular electrical engineering technology to reduce power consumption and dissipation within industrial switching power supplies, improving their efficiency and performance.
To understand what this is all about and how power supplies with PFC improve the performance of an industrial electrical system, let's start by defining some key terms such as power factor and efficiency.
Power Factor: what is the Power Factor?
In the electrical distribution network, the alternating current may be out of phase with the supply voltage, causing asynchrony in frequency and in the reaching of peaks and valleys. This phase shift produces a more or less important power loss, depending on the magnitude of the phase shift angle between the two vectors, defined as the power factor.
The power factor consists of the following elements:
- Active power: the energy actually used by electrical appliances;
- Reactive power: an amount of energy that is dissipated within the system, but is still essential to ensure the operation of the electrical appliance;
- Apparent power: represents the total amount of electrical energy actually used.
Specifically, we can therefore define the power factor as the ratio between the active power and the apparent power, which can identify the power loss caused by the reactive power.
The value, expressed as a decimal scale or as a percentage, increases as the reactive power decreases, indicating that the power system has a high level of efficiency. Conversely, the lower the power factor, the higher the reactive power, indicating a high level of inefficiency.
In fact, if not properly managed and disposed of, reactive power can cause potential risks, failures or malfunctions in the electrical system. Furthermore, unlike domestic installations where the level of reactive power is low and not paid for, in industry it can be a serious problem with very high costs that can worsen the efficiency of the entire power system.
Efficiency in switching power supplies
Electrical efficiency expresses the ability of the power supply to best convert the input power to the output power it supplies to devices. A good level of efficiency is important to reduce energy consumption and heat loss with each use of the power supply.
The efficiency of a switch-mode power supply depends on two factors:
- The power supply cooling system: some closed-chassis power supplies are cooled by a built-in fan, others are cooled by free-air convection.
- The power factor of the power supply: the higher it is, the lower the energy transmission losses and the better the voltage regulation on the electrical current.
To summarise, the closer a power factor is to the ideal values of 100% or 1, the more efficient the power supply will be and the more energy it will be able to use.
Conversely, an inefficient power supply with a low Power Factor will use more power from generators and power lines, but this will be bounced back and not actually used.
For this reason, modern switching power supplies use Power Factor Correction Technologies that help to increase the power factor of the power supply.
Power Factor Correction: power supplies with active or passive PFC
PFC technology, also known as power factor correction, is therefore intended to correct the power loss and increase the efficiency of the power supply. There are two types of PFC: active or passive, the difference being in the composition of the circuit and the electrical components.
In a power supply with active PFC, advanced electronic circuits consisting of boost converters, bridge rectifiers and input capacitors are used to optimally distribute the power to the connected devices. This is the most modern and effective solution.
Instead, a power supply with passive PFC uses capacitors and inductors placed in series to improve power distribution. This is less complex and expensive, but also less efficient.
By comparing the efficiency of power supplies with and without PFC, we can give some examples:
- A power supply without PFC can achieve a power factor between 50% and 60%;
- A power supply with passive PFC can achieve a power factor of up to 70% or 80%;
- A modern switching power supply with active PFC achieves a power factor of over 90%.
In fact, the highest efficiency industrial switching power supplies have a power factor of at least 80%, in the best cases reaching a Power Factor of 93% or 95%.
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The advantages of an industrial power supply with PFC
With all this in mind, it is easy to understand what a low power factor power system can mean for industries. Equipment failures, overheating of installations, unstable operation of the electrical system, not to mention a high waste of current that is absorbed and dissipated unnecessarily, together with a general increase in industrial energy costs.
A modern power supply system, consisting of industrial switching power supplies with active PFC, offers numerous competitive advantages for companies:
- Reducing energy management costs by increasing efficiency quality;
- Reduction in the mean time between failures of powered devices (motors, machinery, etc.);
- Reduction of voltage drops, power surges and power demand.
As industrial power supply experts with over 20 years of experience and know-how, at Digimax we offer the widest range of switching power supplies for industry with active Power Factor Correction, in a stock of thousands of products for immediate delivery and at favourable prices.
We are partners with industry leaders such as Mean Well, with whom we work in the Digimax LAB to test, repair and customise switching power supplies for a wide range of industrial applications, in order to offer a complete and integrated service.