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Case Studies

You may not always know what it is you want for your business, or even if it is possible. We find it important to highlight certain case studies to show you just what can be done and that we will always do our utmost to meet your requirements.

Case Study 1

CE + CE - Does not equal CE

A client came to us with a computer that had been constructed from various off the shelf sub-assemblies. There was a specific application for the PC and one of the design criteria was to enclose all of the sub-assemblies including the LCD screen panel into a metal housing. During the design process the client had taken extreme care to ensure all of the sub-assemblies had been tested and were CE compliant in their own right. It was therefore only logical to him that as all sub-assemblies were CE compliant that the final product would automatically comply.

During the process of verifying the EMC compliance of the computer it very quickly became apparent that there were significant non-compliances. These included radiated emissions and susceptibility to electrostatic discharge or ESD.

We identified that a number of metal panels had been used to manufacture the cabinet housing and several of these had been powder coated thus insulating the panel from the main chassis. This was allowing some of the metal panels to re-radiate RF emissions from within the computer rather than helping to screen them. Removal of the coating from the contact areas of the metal panels immediately resolved the radiated emissions problem and at the same time overcame the ESD non-compliance. This simple modification also addressed a potential protective earthing safety issue.

Case Study 2

29p saves the day

Product EMC compliance often requires testing of immunity to surges on the mains power feed and possibly other inter-connecting cables. This involves injecting a very high energy pulse into the mains supply of the product under test and this can be as high as 2000 volts. With such a large amount of energy being applied it can sometimes have catastrophic results, occasionally these can be quite spectacular.

A client requested us to carry out EMC testing on some sensitive scientific analysis equipment. One module alone cost in excess of £50,000 to produce. As the final product was intended to be used in a semi-hostile environment we explained that surge testing would be necessary, However there were serious reservations from the client about subjecting the unit to such treatment.

We reviewed the schematic diagram for the main power supply within the product and indeed concurred with the client's concerns in carrying out such tests. We calculated that there was more than a 60% chance that the product would have sustained serious damage.

Our solution was to add a transient voltage suppressor or varistor to a specific area of the power supply. The result being that the equipment withstood all of the surge tests and continued to function perfectly.

Simply taking a product in and testing it without consultation can end up with severe consequences, both in terms of product damage and time delays. By working closely with clients we are able to address these issues whilst testing products and provide practical advice.

Not bad value in terms of insurance - 29p to protect £50,000 of capital expenditure.