Topic

The “real world”

Factory conditions are deliberately as consistent as possible, not just to make it more comfortable for the workers, but also to enable the products produced to be tested under known conditions, and thus compared accurately against each other. It is unusual for any but the most rugged military products to be fully tested over the range of conditions that they will experience in the real world. The ‘real world’ consists of extreme temperatures and changes in temperature, a range of mechanical hazards, and contamination from the environment.

Taking these in turn:

Typically equipment that is work- or office-based has an ‘easier life’ than portable equipment, and both enjoy a relatively benign experience compared with military and automotive applications. Arguably the hardest life of all is that of a piece of equipment that exists in a car engine compartment – the so-called ‘under-hood’ electronics.

In Table 1, we have tried to compare the environmental conditions experienced by various types of equipment. Each is rated on an arbitrary 1–10 scale, representing a range of impacts from minimal to extreme.

Table 1: A comparative assessment of the environmental conditions to which different classes of equipment are exposed
environmental condition mobile phone personal computer car engine management system military aircraft radar
temperature extremes 3 1 10 8
thermal cycling 4 3 10 7
acceleration; vibration; bump; shock 5 2 9 10
humidity 4 2 10 8
dust; mould growth 4 3 9 10
electromagnetic environment 5 3 7 10
Classified on a scale of 1 = benign to 10 = severe

Obviously the scale is relatively arbitrary, but it is worth noting that some level of hazard can be associated with most items of equipment.

In some cases, the conditions will depend on the user – you may always be careful not to drop your mobile phone, but there are others who do, and in consequence many failed phones! Also, although nothing more is said about this aspect during this module, one has to consider the electromagnetic environment. In other parts of this module, we have mostly considered the EMC aspect, but one of the reasons that a military aircraft radar has a more severe classification is that it needs to withstand the high electromagnetic pulse from a nuclear event!

It becomes very important to know the detail of the ‘real world’ in which your equipment will be operating, in order to make informed choices for technology and construction. Challenges in our real world also include:

In the real world there are also differences between normal and abnormal operation. For example, with industrial computers and motor drives, it is not unusual for equipment to be specified to operate at a high dissipation for restricted periods.

Finally, in the real world, one needs to make provision for likely accidents. You may decide not to have a coffee-proof keyboard for your workstation, but an equivalent function in an industrial environment may need a different input mechanism, in order to guard against operators with gloves dripping unknown fluids!

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