Efficiency is a critical factor in the design and functionality of power supplies, impacting both performance and operational costs. In basic electrical terms, efficiency is the ratio of the usable power output divided by the input power. This ratio is often expressed as an impressive percentage, usually greater than 90%.
But in the measure of the efficiency of a power supply, just how efficient should an efficient power supply be?
As a benchmark, let’s consider a typical 24 VDC, 20 A, 480 W power supply.
The PULS CP20.241 power supply has an efficiency of 95.6%, where an alternate brand with the same power rating has an efficiency of 92.5%, and another alternate brand has an efficiency of 94%.
The PULS CP20.241's efficiency of 95.6% means the power supply's losses are 4.4% (100%—95.6%), so the actual losses of the power supply are calculated as 480 W x 4.4% = 22W.
Alternate brand #1 with 92.5% efficiency has losses of 7.5%, equivalent to 480 W x 7.5% = 36 W. Alternate brand #2 with 94% efficiency has losses of 28.8 W. These power losses are actual heat dissipated into the enclosure from the power supply.
| Brand |
Efficiency (%) |
Heat Loss (W) |
| PULS CP20.241 |
Alternate Brand #1 |
Alternate Brand #2 |
| 95.6 |
92.5 |
94.0 |
| 22 |
36 |
28.8 |
Power Supply and Heat Loss Comparison
Comparing the three examples, Product #1 dissipates an additional 14 W, or 64% more heat, than the PULS CP20.241, and Product #2 dissipates an additional 6.8 W or 31% more heat.
The heat generated in losses needs to be minimised in an enclosure as it can potentially adversely affect surrounding equipment and require some extra cooling power to mitigate this additional heat.
From an economic perspective, the additional losses simply waste resources. Let’s take a network of 10 power supplies operating in a large-scale industrial plant as an example. With each power supply running for 21 hours a day, 300 days a year over a decade, even small differences in efficiency can lead to substantial economic and operational impacts.
The additional costs associated with operating the less efficient alternatives are:
- Alternative #1 – the additional 14 W of heat will cost an extra $2,646.00 to operate over this period.
- Alternative #2 - the additional 6.8 W of heat will cost an extra $1,285.20.
Our analysis shows that choosing the PULS CP20.241 over its less efficient counterparts could save thousands in energy costs—money that would otherwise be literally dissipated into thin air.
The calculations are based on a small number of power supplies in the installation. It also assumes the energy costs will remain unchanged for the next 10 years, which is unlikely.
The industry does not have money to burn. However, that is exactly what we are doing when we use less efficient power supplies. A simple change of thinking at the outset will provide a lasting return over a plant's lifespan.
Beyond cost savings, regulatory trends increasingly favour higher-efficiency power supplies. With global pushes towards reducing energy consumption and minimising environmental impact, efficient power supplies are becoming more beneficial.
PULS is dedicated to producing the most efficient DIN rail power supplies available on the market. IPD proudly represents PULS in Australia with local expertise and application support.
For more information, contact IPD at 1300 556 601 or visit here.