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How To Prepare For EMC Testing

By Ryan M. Urness, Laboratory Manager


Abstract

Experience has shown that a product’s compliance program frequently occurs as an after- thought following design and production planning. Yet a compliance program that is well prepared in advance provides increased accuracy and greater efficiency. It also enables significant cost savings and expedited time‐to-market.

Introduction

Product testing, qualification and regulatory compliance – every design engineer encounters these necessities during the tenure of a career. An effective compliance program in this context is not solely a matter of efficiency; rather, efficiency should be an inherent component of an effective program, and it results from the organization’s experience and understanding of various test programs, and the ability to achieve its goals.

This article is the first in a four‐part series providing guidance in building an effective compliance test program. Though examples provided in this article refer primarily to EMC compliance, the fundamental philosophies of preparation and planning are applicable across disciplines.

Find the Market, Know the Standards

The first step is to research applicable regulatory requirements for the product. This step requires understanding the product’s markets and the requirements of countries where it will be offered. Considering these factors will uncover legal requirements, directives, and standards which will be imposed on the design.

Such requirements arise primarily from two sources: governmental agencies and the product manufacturer. The first source is legally mandated, while the second source is imposed.1

Regardless of the compliance program’s source, recognizing conformity assessments will assist engineers through all phases of the product’s development.

A product offered only in the U.S. is subject to different legal requirements than the same product offered internationally. Products which are intended for international markets may require additional testing, which increases the cost of the compliance testing.

Mutual recognition agreements (MRAs) may exists between countries, allowing the demonstrated compliance to one country’s requirements to substitute for another’s; however, additional declarations or documentation may be required to alleviate inconsistencies in reporting.2

It’s equally important to understand limitations imposed on products from country to country. Although efforts have been made to harmonize requirements internationally, there is no all inclusive caveat allowing a product to be marketed everywhere.

Interpreting applicable standards and understanding multiple inclusions and exclusions of MRAs is a complex and often confusing process. Selecting an independent laboratory as a partner is an efficient way to ensure that the product’s compliance will be subjected to all requirements.

Selecting a Compliance Partner

The compliance partner’s years of experience with the homologation (that is, the official confirmation) process can significantly reduce the amount of research required in identifying applicable requirements. This is usually provided as a complimentary service, depending on the scope of the project.

Companies often choose a compliance laboratory because of cost or availability. These factors are important but should not be the principal motivation in selecting a test laboratory. A competent test laboratory will become a partner in the conformity assessment process3 and will establish a mutually beneficial relationship with the client.4

The experience and competency of the compliance partner is directly proportional to the efficiency with which the compliance program will be executed. This translates to significant savings in the cost of compliance. A mutually beneficial relationship develops between the compliance laboratory and the client as the laboratory assists in the preparation and planning phase, develops familiarity with the customer and product, and performs the full range of testing required for regulatory conformity.

For more detail on methods of selecting a compliance partner, refer to Conformity Magazine’s April 2008 article “Test Laboratories – Finding Them…and Working with Them” or Walter Poggi’s April 2007 article “Selecting an Independent Laboratory”; both of which are available on Conformity’s website.

Design Considerations

The second step in preparing and planning an effective compliance program is to implement design parameters that encompass applicable regulatory and quality standards. Every engineer should understand that the primary goal of design is meeting product requirements; however, designing products to meet regulatory requirements is equally important.5

It is useless to design a product that cannot meet applicable regulatory requirements, regardless of advantage, application or market share; the product simply cannot be sold.

Shortened development cycles, with a considerable reduction in allowances for research and development; time‐to‐market schedules measured in weeks/months rather than years; and the proliferation of regulations and updates all challenge the design engineer’s ability to design for compliance.6

Losing focus on compliance could increase time to market, elevate costs, and create unrealistic expectations for production. Products that require post‐design fixes to remedy compliance anomalies often incur unexpected costs for production, modifications to production planning, or even reversion to the design phase.

Whatever the case, these equate to increased testing cost and an extended compliance program schedule. A good rule of thumb is recognizing that components incorporated into designs for compliance purposes can always be removed later if proven unnecessary; incorporating components after a design is complete will be exponentially more difficult.

Utilize Continuing Education

Information is available on best engineering practices on designing for compliance, testing phenomena, and ways in which the regulatory process affects design criteria. Additionally, product requirements and standards are dynamic – continuously refined and updated. Technical interpretations and test methodologies are constantly evaluated, with mutual agreements revised between committees and laboratories. Frequently, these updates, decisions and interpretations affect the methods in which compliance is determined for products.

Information on these topics is available through trade publications, industry or technical society symposia, and educational programs sponsored by compliance facilities.

Engineers have a responsibility to continue their education on product compliance, and the compliance partner can provide guidance on how to facilitate this learning.

Build Management Support

The third step in preparing an effective compliance program is gaining the management team’s support of the compliance process.

The engineering team’s understanding of the importance of a well‐defined compliance program is essential; however, ensuring that the management team recognizes this importance is equally crucial. Concepts and requirements should be clearly stated and

agreed upon among all departments involved, and necessary resources must be made available during the program’s preparation and execution.7

Appreciating that “designing for compliance” will save significant time and cost during conformity testing is a key component of an effective test program.

Taking a Proactive Approach

The fourth step requires being proactive during the design phase.

Pre‐scanning is a proactive method of building a successful compliance program. Pre‐scan measurements may be facilitated by the manufacturer or the compliance partner, depending on complexity and resource requirements for the intended measurements.

Pre‐compliance measurements are intended to give approximations of performance8 and do not guarantee compliance. To help save money for the customer, the scope of pre‐compliance testing is often abbreviated. However, pre-compliance measurements can be leveraged during final compliance testing, depending on the changes implemented to the product between the pre‐compliance and the final compliance phases.

Another approach to cost reduction in pre-scanning is to coordinate measurements with the compliance partner and correlate them (relatively) with measurements observed in house during the design phase. This approach, too, can approximate performance and expose problem areas needing attention prior to the testing phase, although these measurements will pose a higher level of uncertainty as a result of a noncompliant test configuration. However, there may be value in this approach to methodology as a precursor to a scheduled pre-scan with the testing facility.

Documentation, Information and Operation

The final step in preparing and planning an effective compliance program is making sure that all documentation and information relevant to the product is available before requesting a quotation for test services from the compliance partner.

Compliance test facilities will often provide a test plan guide or worksheet that will assist in gathering relevant information required during the test program.

This test plan guide will assist in the development of an effective test plan, but it’s still a good idea to discuss the project with the compliance partner to ensure that all bases are covered.

First and foremost, ensure proper operation of each test sample that will be supplied to the testing facility. The largest contributor to delays in the testing schedule (outside of product noncompliance) is anomalous operation of devices provided for testing.

Second, coordinate with the test facility the operational modes that will be required during the compliance program. This might include developing special test software/firmware exercising the device’s functionality, monitoring the essential functions of the device while under test, or configuring the product into its multiple modes of operation.

Third, provide as much documentation regarding the product as possible. This may include but is not limited to schematics, block diagrams, theories of operation, application descriptions and any applicable peripherals.

Finally, to supplement this documentation, create an operating procedure for the product that describes essential functions and performance criterion. Additionally, outline expectations in the event of an observed conformity issue.

Proper attention to detail will ensure a higher probability of success during final compliance.

Conclusion

The cost of ensuring compliance is real and is subject to rapid increases when not properly planned. Preparing and planning an effective compliance program will include researching applicable regulatory requirements for the product; implementing design parameters that encompass these applicable requirements; being proactive during the design phase by incorporating best practice design techniques and performing pre‐scan measurements prior to the launch of the final compliance program; gaining the support of the management team in the compliance process by demonstrating how designing for compliance will save significant time and cost during final conformity testing; and ensuring that documentation, information and operating procedure relevant to product compliance is available in advance.

The next article in this series will review the quotation and scheduling processes and explain why they are essential components of an effective compliance program.

Resources

1. Paul, Clayton R. (1992). Introduction to Electromagnetic Compatibility. New York: Wiley‐Interscience (p. 42).

2.  Zombolas, Chris. (2000). Mutual Recognition Agreements – Problems Caused by Inconsistencies in the Accreditation Requirements of EMC Test Laboratories. EMC 2000 IEEE International Symposium, Vol. 1 (pp. 257‐261). Retrieved from www.ieeexplore.ieee.org (p. 257).

3.  Editors of Conformity (April 2008). Test Laboratories – Finding Them…and Working with Them. Conformity, 13(4), (pp. 48‐54). Retrieved from www.conformity.com

4.  Poggi, Walter (April 2007). Selecting an Independent Laboratory. Conformity, 12(4), (pp. 50‐55). Retrieved from www.conformity.com

5.  Schmitt, Ron (2002). Electromagnetics Explained, A Handbook for Wireless/RF EMC, and High‐Speed Electronics. Oxford: Newnes/Elsevier (p. 251).

6.  Sims, Thomas P. (2001). The Planning and Implementation of a EMC Successful Product Safety Program. EMC 2001 IEEE International Symposium, Vol. 2 (pp. 771‐773). Retrieved from www.ieeexplore.ieee.org (p. 771).

7.  Sims, Thomas P. (2001). The Planning and Implementation of a EMC Successful Product Safety Program. EMC 2001 IEEE International Symposium, Vol. 2 (pp. 771‐773). Retrieved from www.ieeexplore.ieee.org (p. 771).

8.  Hewlett Packard (1999). Cookbook for EMC Precompliance Measurements – Application Note 1328. Colorado: Hewlett Packard (p. 4).

About the Author

Ryan Urness is laboratory manager and an EMC engineer for LSR. Ryan has enjoyed nearly 14 years in the product qualification and compliance industry, with broad experience in systems design and integration, process automation, and engineering for dynamics, environmental, electronics and EMC testing. His undergraduate study was in electronics engineering technology and organizational management; and is a graduate student at the Milwaukee School of Engineering. Ryan can be reached at rurness@lsr.com or 262.421.4969.