"Thermal imaging? Of the CP10?" echoes the person who answered the phone. "Of course we can do that for you! But someone else is using the infrared camera at the moment. I'll let you know when I have it back." Infrared cameras are hot property in the PULS development department and are constantly in use.
But why is it worth making all the effort of performing a thermographic analysis? It all starts with the unique 'cool design' of PULS devices.
The three principles of 'cool design'
The term 'cool' is appropriate here on two levels. Obviously, PULS aims to impress with devices that feature a premium housing and look stylish. But the primary meaning of the word 'cool' here is in the physical sense, i.e. in relation to temperature.
Because the biggest problem faced by power supplies with slimline designs is heat generation 'cool' designs are required, resulting in efficient, durable and aesthetically pleasing DIN rail power supply units.
'Cool design' follows three very simple principles:
- Achievement of maximum efficiency values
- Optimisation of the cooling of the power supply
- Careful consideration of the positioning of sensitive components
But the question is, how can we visually demonstrate that the 'cool design' is also able to work to its full potential when it is under load? Such a practical test is where thermography is needed.
The telephone starts to ring. "The camera's back now, so you can stop by." The infrared camera has finally been returned to the developer and the test set-up is ready for a PULS CP10.241.
After just a few settings have been altered on the camera, the first thermographic images appear on the display. This type of thermal imagery is incredibly insightful for convection-cooled power supplies like the ones developed by PULS.
Convection cooling involves a flow of warm air being transferred outside. The effect of a functioning air flow can be recorded by thermography.
The thermographic image of a PULS CP10 clearly shows that sensitive components, such as electrolytic capacitors (image key: 1, 2, 3, 4, 5), have been positioned perfectly for ventilation, allowing them to be kept cool.
The convection air flow inside a DIN-rail power supply needs to be able to flow as freely as possible and mustn't be interfered unnecessarily by components. Cooling ducts are installed accordingly for this purpose and thermal flow measurements performed.
There are noticeably fewer temperature-sensitive electrolytic capacitors in PULS power supplies than in products from the company's competitors. The dimensions of the electrolytic capacitors are also noteworthy – whilst these sensitive components are becoming ever smaller in competitors' products, and consequently have a shorter life span, PULS only permits the use of electrolytic capacitors with a diameter over 8mm and a correspondingly high level of quality.
If the temperature within a power supply increases by 10°C, the service life of the electrolytic capacitors will be halved – and that's without even factoring in its current load.
This manifests itself in a considerable reduction in capacitance. Although this loss won't necessarily lead to the immediate failure of the power supply, it will have a seriously detrimental effect on the lifespan of the device as a whole.
It is for this reason that the developers at PULS give very careful consideration to the optimum positioning of the electrolytic capacitors and other temperature-sensitive components, such as varistors and optocouplers. On the basis of resonant designs, they place the components that have an effect on the service life as far away as possible from the 'hot' components, such as the transformer.
The successful results of this approach are clear for all to see in the thermographic images.