The power supply you choose today will largely be dictated by the way that product will be used in the years to come, explains director of sales and marketing, Excelsys Technologies, Dermot Flynn.
Selecting and specifying power supplies is a task that must be approached with great care. There are many factors to consider, such as the application, the environment in which the system and power supply will operate and, of course, the electrical and technical parameters that the power supply must achieve.
Any decision is further complicated by the sheer variation of power supplies available ranging in package type from wall plug adaptors for mobile phones and external power supplies typically used in laptops, though to open frame, enclosed and encapsulated options. There are also fan-cooled, fan-less and conduction cooled power supplies. With such choice it can be difficult to select the best supply for the application in question. Two of the most crucial factors governing any choice are the end user application and the operating environment.
What is the application?
Power supplies are used in many different market segments including communications, computing, industrial, medical, lighting and defence and aerospace. The end-use application of the system will have a major bearing on the power supply, as each industry will have specific regulations and standards to which any buyer must adhere. Identifying the correct product type to meet any relevant safety and electromagnetic compatibility standards can greatly simplify the selection.
Of course, different market sectors will stipulate different standards. Information technology equipment should meet IEC60950 second edition, while medical equipment must adhere to IEC60601-1 third edition and IEC60601-1-2 fourth edition for EMC. Defence and aerospace applications need to demonstrate MIL461 (D/E/F) for EMC while for lighting applications, buyers should address IEC61347 standard.
There are key differences between each of these standards, with various parameters that must be met prior to equipment certification. It is therefore important to select a power supply that is certified and characterised to the industry standards that the equipment must ultimately meet. Examples of this include the CoolX, Xsolo and UltiMod series from Excelsys, which carry IEC60601-1 third and fourth edition certification for medical equipment. This makes them ideal for use in equipment such as imaging, electro-medicine, lasers and clinical chemistry.
What is the environment?
The environment in which equipment must operate is another important consideration during power supply selection. Operating conditions for different types of equipment can vary greatly, from home environments for laptops and mobile equipment, imaging equipment in hospitals, right through to harsh environments such as those experienced by shipboard electronics and outdoor applications.
Various factors need to be considered including the operating temperature and air flow in the system, as well as assessing whether the application is subject to dust or water ingress. Bear in mind also whether the equipment will be subject to significant shock and vibration.
Defining these environmental conditions will dictate the type of power supply that will be suitable. For acoustic or vibration-sensitive applications such as broadcast and scientific equipment, a fan-less power supply is preferable. It is therefore important to understand the ambient air temperature around the power supply, to ensure that it will operate within its specifications.
If a system is destined for use on vehicles or boats, it will need to be sufficiently rugged to withstand shock and vibration. In these applications selecting a power supply that is characterised to MIL-STD 810G is prudent.
There are many factors to consider when identifying the right power supply. The chosen product must meet any electrical and electronic requirements of the system to ensure it operates correctly and, of course, the characteristics of the load, controls and communications standards will all define the electrical specification of the power supply. In addition to these factors, however, the environment in which the supply will operate, as well as the regulations that govern that market segment, must be closely followed to simplify system design and ensure product compliance.