Magnetic and electric fields cannot be seen with our eyes, making magnetism an abstract field. Maxwell and his precedents did a great job, but we have to admit that those great bunch of differential and integral equations are not that easy to implement in day-to-day work. The work of EMC engineers is rooted in them. Equations can be quite theoretical, but their work is highly concrete. Sometimes it is not that evident to see what they do in their daily work, so today’s article tries to explain what are some of their tasks.
What is EMC?
Electromagnetic Compatibility, or EMC, is the ability of electronic devices to work close to each other without disturbing the rest of the devices and without being disturbed by them. In short, EMC is the science of guaranteeing peace between electronic devices. Yes, it is science, not magic. Many people, even high-skilled people working in electronics for a long time, think of EMC as a magic process. This is a thinking that needs to be reoriented with education, and one of the pillars of clearemc.
How EMC is guaranteed?
As EMC is a science, its efficacy must be shown by testing. A set of tests, performed with very specific means, shows the level of disturbance produced by a device (emissions) and the level of disturbance that it can support (immunity).
Tests simulate the real environment as much as possible. When it is feasible, extreme conditions will be tested. For example, if you want to test a washing machine, you will need to load it with its maximum load.
The truth is that compliance in the real world can not be completely verified. It is not possible to simulate all the situations in which an electronic device will be used. What we really do is to allow an extremely low level of emissions and disturbances, so we will be almost sure that the devices will not have problems once they go out to the market.
What are the tasks of an EMC engineer?
It can vary depending upon the enterprise, the development strategy (if any), the team size and, the objectives. Here are the main tasks and EMC engineer usually perform:
It is quite common that an EMC worker arrives at a project when it is already designed, assembled and, mostly validated. This is a very bad idea, but this will be history for another day. Therefore, the main task is to review what has been done and identify the main potential problematic points. The electronic schematics and Printed Circuit Board (PCB) plans are the main documents to review, but also the mechanical plans.
When necessary, some boards will be redesigned. Sometimes is to change the layout, others are to add a filter or some components that play a role in EMC behavior. On top of that, mechanical parts, mainly when there are metallic chassis, play a key role in emissions and immunity, so they need to be carefully designed.
EMC is not different from other fields, so it is constantly evolving. Read and study are part of the main tasks of EMC people. It can be in form of application notes, training, books, seminars, even testing. One of the main bottlenecks of EMC is the lack of accessible training and resources.
Filters are electronic circuits that attenuate unwanted signals within a circuit. Therefore they are one of the protagonists within the life of EMC people. Filters need to be designed and, when possible, simulated. There is a myriad of filters and one of the most commonly faced issues is to design a good filter, that mechanically fits within a system, and also that can be integrated into the production phase. Besides, filters in real life are not perfect, so their possible countereffects need to be analyzed.
Tests can be in-house or in external laboratories. Pre-compliance tests or debugging tests are usually done in-house, before going to an external laboratory. The type of tests done in-house facilities depends upon the available budget and the importance given to the EMC part of the project. Unfortunately, it is quite common that tests are executed for the first time in a certified laboratory when there is not much place nor time for reaction.
Read and write documents
This is a less interesting part but, as in many other jobs, necessary. There are some key documents within the life of EMC:
- Standards: official documents that dictate the rules for the tests such as the set-ups or the criteria for passing the tests. There are many different types of standards and vary according to the country, market and, type of product. The Academy of EMC shows a good explanation about standards.
- Test plans: certified laboratories usually ask for a test plan. They usually know very well the standards, but each electronic device is different, so tests need to be adapted to each of them as well as each use case.
- Test reports: once the tests are finished, they gather all the results, interpret them and generate all the necessary documentation for the project stakeholders.
This article has been firstly published in Medium