Everything you ever wanted to know about control panel power supplies but were afraid to ask

Most modern high-speed, high-performance sensors and controllers require a reliable DC power source. Used in commercial applications, traditional, linear power supplies that relied on transformers to convert AC input into more manageable DC output are now being replaced by more compact and efficient switching power supplies.
Control panel power supplies are now taking this technology further, allowing businesses to operate using a DIN system that allows controllable power supply delivery to a range of applications.

Switching power supplies convert a DC voltage into a lower regulated voltage by storing the difference in a magnetic field. Because this removes the need for large coils within the system by incorporating smaller electronic methods of conversion, the size of the control panel power supply is reduced and more energy efficient. Switching power supplies are typically over 80% efficient, compared to 50% efficiency from linear power supplies. They are also light enough to be mounted on a DIN rail, which only the smallest linear supplies are capable of doing.

With modern development in power supply technology, switching power supply units often incorporate more advanced features as standard. Power factor correction (PFC) limits the harmonic current on the input side of the power supply, ‘cleaning’ up the input current which reduces the peak current demand. Overload protection protects the power supply from any damage caused by an abnormal rise in output current, and in turn protects any equipment that may be feeding off the power supply.

Overvoltage protection (OVP) prevents load circuit damage by cutting the power supply output when output voltage rises above 120% of the rated value. If the power supply feedback loop fails, for example, the output voltages could rise to levels that may cause major damage to the entire system. OVP detects this high voltage, shorts the output and causes the supply to shut down, preventing a surge that could be catastrophic.

Undervoltage detection indicates if the output voltage drops below a certain level.

When you’re planning to replace your control panel power supplies, there are a few things you need to consider. Firstly, what applications is the power supply intended for? You will need to know your input voltage and frequency, the output voltage, the wattage or power in amperes and the peak loading of the output. You will then need to calculate the power of the DC power supply you need. If more than one output is required, you will need to carry out a quick calculation to determine the total wattage for the supply by multiplying the voltage by the amperage of each output to calculate the individual wattage and then adding these together to give you your total wattage requirement.
You will also need to check the enclosure style, connections and physical size of the control panel power supply to make sure that it is suitable. A unit that is too large may not be suitable for some DIN rail fittings whereas a compact unit may not have the capability to cope with the number of outputs needed.

Although buying a second-hand unit on a web auction site may seem like a good way to save a few pounds, your control panel power supplies must conform to all safety legislation. Buying from a reputable dealer who offers a selection of approved and certificated units is the only safe and proper option when it comes to buying control panel power supplies.

Finally, consider the application that you wish to apply the control panel power supply to. This can include the power supply life, custom power ratings or mixed voltages. A good power supply will need to be able to cope with every requirement you have without having to work at maximum capacity for prolonged periods of time, which can shorten its lifespan. Talking to a technical expert who has experience in fitting control panel power supplies into commercial environments will give you more information and help you make an informed choice when it comes to selecting your power supply requirements.