How to Create an EMC Test Plan for Your Automotive Product
The test plan you provide for automotive EMC testing is a significant factor in how smoothly your testing will go and how quickly your product will go to market. A clear, comprehensive, and well-developed test plan will prevent a variety of problems and delays, but a test plan can be a daunting document, and many engineers, especially newer engineers, don’t have a complete picture of how to create an EMC test plan or how to choose a laboratory that is a good fit for the product’s testing needs. This paper will cover what general information needs to be in the EMC test plan, how to develop the plan, if and when to modify the plan during testing, and how to choose a testing facility that is best suited to your needs.
Planning the Test Plan
The first and most important aspect of EMC test plan development is clear and consistent communication within your organization about the product, its functions, and its EMC testing requirements. Depending on what OEM the plan is for, you may have a test plan template available that will provide an outline for you, so check what templates are available within your organization. Otherwise, you will need to lay out your plan from scratch. Many experts and stakeholders need to be involved in plan development to provide a complete perspective on the product being tested, otherwise, you may fail to include a feature or some technical information in your test plan. Typically, you will want input from people such as hardware engineers, software engineers, and a validation engineer, but exactly who needs to be involved will vary based on the product and the organization.
Once you define your stakeholders and their responsibilities, schedule regular test plan reviews from the outset. Set aside time each week to briefly check in and assess progress and milestones. There is now more pressure than ever to get new products to market in a very narrow time window, so taking control of your timeline and accurately accounting for any potential delays both in test plan development and during the testing phase is critical. Once you define these inputs, you can begin developing the test plan itself.
Test Plan Development Pre-Planning Tips
- Find out if a test plan template is available to you.
- Make a list of stakeholders whose input will be necessary for the test plan.
- Define responsibilities – who is responsible for filling in what information?
- Set a realistic timeline for finalizing the test plan that accounts for reviews and possible delays.
- Schedule consistent check-in meetings.
- Define milestones for the plan development and identify potential roadblocks.
Developing the Test Plan
If you are not starting with a template, you will need to define the test plan structure. Make the document easy to navigate by dividing the information clearly into logical sections. Starting with the table of contents is a good way to define your information “buckets” so that, as you add pieces of information to your test plan, you can place them where they make the most sense. Even if you are starting with a template, make sure every section is complete and that the information you include is both relevant and detailed.
It is important to think about the test plan from the perspective of the testing professionals, who will essentially be using it as a set of instructions. The structure and flow of the test plan is very important to its comprehensibility. Test plans can be long, dense documents, and if the testing personnel have difficulty understanding the document or struggle to find the critical information they need, this can cause significant delays. Remember that, although they are testing experts, the people testing your product are not experts on your specific product and do not know your intentions for its functionality and use conditions. If you already have a relationship with a testing facility, you can get in touch with them and ask for test plan advice and recommendations. The perspective of a testing professional can provide valuable feedback and alert you to problems you may not have considered, which will save time and hassle during testing.
The technical information about your product must be detailed and precise. Part numbers must match, measurements must be correct, and diagrams must be accurate to the specific version or iteration of the product under test. Even in cases where a test technician can easily see the source of an error and understand what your intention was, the parameters of a lab’s accreditation will generally require that they stop testing and get a correction documented in writing before they can proceed. For that reason, it is also very important to include contact information in your test plan. For any given aspect of product testing, you should define who has the power to approve changes or corrections and include their contact information clearly in the test plan itself.
You should define not only the physical and mechanical aspects of the product but also the product’s intended function and any conditions that are specific to how it will be used, as this will inform how it is to be tested. Define its modes, its expected function in those modes, and how that functionality will be tested – including “off” mode. Define input and output requirements, monitoring parameters, and detailed test setup information. If you can do any preliminary testing in your facility, experiment with inputs and test setups and compare your process to the process you describe in the document. You may find that something you described in your document does not work in practice. If you have any EMI or EMS analysis, data, or findings, include that in your test plan as well. This can help the testing lab narrow down the source of a problem, or adjust testing parameters accordingly for faster, more accurate results.
Referencing other test plans can be helpful, but do not copy and paste information from another test plan without an extremely thorough review, even if the information is for a very similar product. Diagrams may be different in ways that are not readily obvious, and incorrect measurements or part numbers copied over may be difficult to catch, which can create problems when the product is being tested.
It’s rare to have a truly perfect test plan that can be executed with no questions, follow-ups, or revisions, but the more problems there are, and the more significant those problems are, the more delays they will cause. You should strive for precision and completeness rather than relying on the testing facility to catch problems, but also be prepared for the fact that questions will almost certainly arise. Stay calm, be attentive to questions from the testing facility, and be prepared to make changes to the test plan if necessary.
Test Plan Creation Tips
- Develop a clear document structure and organize information neatly.
- Define realistic start and completion dates for testing – include “buffer” time for changes/delays.
- Think from the perspective of the testing lab.
- Make sure product information is detailed and accurate, including diagrams and models.
- Include detailed information about how the testing is to be performed – ensure you understand test requirements for your end market.
- Include contact information so questions or errors can be dealt with quickly.
- Be precise, but don’t panic if something needs to be changed, revisions are common.
Choosing a Testing Laboratory
Not all EMC test labs are the same. There’s a lot of overlap as far as certifications and accreditations, but the types of equipment available at the lab and the expertise of the staff is often very industry-specific, so it’s critical to make sure the lab is a good fit for your product, otherwise they may not be able to perform every test you need for the end market you’re working in, and switching labs midway through testing lead to a lot of unnecessary expense and delays.
When you are working with a testing facility for the first time, it may take some time to develop rapport and cultivate the most efficient ways of communicating, but choosing a test facility with experience in your specific end market will make communication easier. If the testing lab identifies anything about your test plan that is atypical for the industry, they can address that with you immediately, and if anything about the test plan is unclear, the test lab can make industry-standard recommendations to help you achieve the best result. They may also have insight about specific OEMs and their requirements that you can benefit from. There is often an advantage to using the same test lab for all your products because the lab personnel develop a familiarity with how your company designs its test plans and what your company’s objectives are.
Although price is always a factor in these decisions, be cautious about asking for a quote before your test plan is finalized. The process of developing a test plan gives you a full picture of the tests you will need, and it’s common for companies to significantly misjudge the scope of their testing and request an inaccurate quote if they have not completed their test plan.
Because changes to the test plan are common, and because elements of the test plan sometimes require clarification, there is a lot of value in maintaining an open, communicative relationship with your testing facility. Even with a strong relationship and good communication, however, test facilities are not psychic, a poorly developed test plan can still cause confusion, unnecessary delays, and unnecessary expenses. Strive to provide the clearest and most detailed test plan possible, and a competent testing facility will do everything they can to execute the test plan exactly as it is written in the fastest reasonable time frame.
Tips for Choosing a Testing Laboratory
- Make sure the lab’s expertise aligns with your end market.
- Make sure they are accredited and equipped to perform the type of testing you require.
- Prepare your test plan before asking for a quote.
- Request a designated point of contact for easy communication.
- Communicate your expectations as clearly and directly as possible.
- Be upfront with any gaps in your own knowledge so the lab can provide advice.
Changing a Test Plan
After you’ve completed all your document reviews and approved your test plan, the next step is submitting it to your chosen testing facility. A competent testing lab will review the test plan before testing and alert you immediately if anything looks wrong, but there are often issues or mistakes that are not obvious until the testing begins. Minor changes to the test plan are not only acceptable but expected. This is why you should build “buffer time” into your timeline to account for delays, and why having a good relationship and good communication with your testing facility is important.
In many cases, changes can be made and approved with a simple email exchange, but a major change may require that you rewrite part of your test plan and re-approve it. It’s important to remember that any lab you use for testing will be accredited to laboratory standards like ISO/IEC 17025 that require specific documentation for all the testing they perform. If the process for making or approving a change to the test plan seems unnecessarily formal, this is probably not the lab’s fault – they are bound by international rules. Always follow the change procedure the lab lays out for you: they may say a confirmation by email is fine, or they may need more sophisticated revisions to accommodate other changes.
Design is an iterative process, and it’s possible that you will need to make deliberate changes to the product specifications during testing or as a result of discoveries during testing. You may need to add tests to the plan, or you many need to change the parameters of a test you have requested. Let the testing lab know as soon as you are aware of any major change, and work with them to understand how best to document this change. Also be prepared to adjust the timeline of your testing. The time it takes to review your document and the time it takes to conduct the test are not the only factors, labs often have queues of work from other companies, so it may be necessary to reschedule your testing by days or weeks.
Tips for Changing a Test Plan
- Changes are likely to take more time than you think.
- Always follow the correct procedure for documenting a change to your test plan.
- Inform your testing lab immediately if you realize a change is necessary.
- Keep lines of communication open and respond promptly to questions.
Completing the Testing Process and Interpreting the Test Report
When testing is complete, the testing laboratory will provide you with a test summary report. If they don’t provide this automatically for some reason, request it. The test summary report will describe all the tests, the results of the tests, and notes on any anomalies or non-compliances. This will be the foundational information for any changes you need to make to the product and will also provide documentary support for any approvals or certifications the product needs.
When you receive the test summary report, you should gather your experts and review it as soon as possible, comparing the report with your test plan and any revisions or change documents point by point to ensure everything on the test plan matches the data you received. If there is anything on the test report that is missing or unclear, reach out to the testing lab and request clarification. Labs occasionally make mistakes, reports occasionally have typos, and sometimes the lab interprets your test plan in a way you did not intend. It is best to resolve any discrepancies as quickly as possible and make sure your testing data provides the information you need.
For your own internal records, store the test plan, the test summary report, and records of any changes or corrections in one place, this will help to eliminate confusion in the future. If you need to make any changes to the product or do any tests over, reference the records you have so you don’t duplicate tests unnecessarily.
Tips for Reviewing Your Test Report
- Review everything shortly after you receive the report to check for errors.
- Ask the testing lab any questions you may have.
- Keep documents well-organized, and store your plan, report, and change log together.
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