The power supply is typically the largest processor of power in the cabinet and therefore power efficiency is an important factor.
Low-efficiency power supplies translate into extra heat in a control cabinet, which necessitates the need for a larger cooling system, resulting in higher energy consumption.
Engineers need to be aware of the efficiencies of the power supplies they design into their control systems.
The typical temperature within a control cabinet operating at 80% nominal power measures approximately 30°C; assuming the power supply is 92% efficient. However, if the power supply is 2% less efficient (90%), it may increase the temperature in the cabinet by as much as 10°C.
Most power supplies today have an efficiency rating above 90% but there is still room for improvement in terms of energy efficiency by the way we load our power supplies.
The best practice is to ensure that the power supply has only 50% loading.
If your project requires 5A of power, choose an efficient power supply that is able to offer 10A. This ensures that at the maximum operating capacity of the design, you are always running at 50% loading (assuming no additional loads were added to the system). But how do you know if your power supply is supplying 50% to the load? You can always use the tried and tested way of using the multimeter.
Phoenix Contact’s new QUINT 4 power supplies have onboard power LEDs displays that will let you know at what level of output your power supply is performing. The LEDs will let you now if the DC supply is “On“, performing at “>50%“, “>75%” or “>100%“. Even without a multimeter, you will be able to determine the current loading of your power supplies in real time.
In my next article, I will show you how to create a redundant, balanced power supply system that will provide you with adequate power efficiently and also extend the life of your power supply.