How to write an EMC Test Plan

We often request that customers complete a test plan before being able to quote for testing. This article will explain why an EMC test plan is so important. Customers new to testing often ask the question “how to write an EMC Test Plan”. So following on from our previous post; Electromagnetic Compatibility Testing Requirements. We wanted to go over and provide guidance on how to get your EMC testing project started. The EMC test laboratory should be able to assist you to some level with helping answer some more of the technical issues.  But, as the manufacturer or importer, you are responsible for the completing the declaration of conformity!

The manufacturer or importer also has a better understanding of the functionality and design of the product. And the intended use including the environment the product will be used in. This is why most EMC testing laboratories may assist in preparing a test plan but won’t complete it fully. The EMC test plan, when completed along with the EMC Test report. It should be kept along with the Declaration of Conformity (DoC) in the compliance folder for each product. This act as a record of how the EMC testing was determined and any judgements on intended use was made.

How to write a test plan? EMC Test plan template

The basic information required for a test plan that should be easily completed by the manufacturer or importer:

• Product identification – The Product name and model number
• Product description – What is the product and what does it do?
• Dimensions and weight of the product. This helps ensure that the testing laboratory has the capability. Also allows the EMC test house to determine the time to perform certain testing.
• Product positional classification. Typicality table top like a PC, or floor standing like a clothes washing machine or maybe ceiling or wall mounted. If the product can be used in multiple orientations or mounting options these should be noted.
• Product power supply requirements. This may include mains products (115/230VAC, 50/60Hz), DC powered products (12VDC etc) or other sources including PoE or internal battery and so on.
• A list of all the ports on the product. Ports maybe power ports such as mains input, perhaps telecommunication ports such as Ethernet or signal ports. Typically it is considered that any hard interconnecting cable is classed as a port. This includes if the cable is fixed or detachable. Interconnections internal to the product that is not accessible to users are not usually considered. This can usually be disregarded from consideration.
• For each port, the cable type (example 8 core, CAT6, shielded cable or maybe mains cable, 3 core non-shielded cable) should be specified.
• For each port, the typical cable length (example 3 m etc) should be specified.
• For each port, the manufacturer and model of the cable should be specified, if specific cables are required and documented in the user manual.
• The number of samples requiring testing. Usually, only 1 sample is required. Yet some Automotive standards and market surveillance EMC testing require more than 1 sample to be tested.
• What modes of operation does the product have? There may be many modes of operation but the basic modes of operation that change the products operating should be stated.
• The configuration of the product. Including any support equipment that provides a load or stimulus to the attached products port must be declared. This is usually best with a block diagram of the components. Used in conjunction with the port/cable table list that should be produced (the details of the4 port/cable list were stated before).
• Details on the test fixtures, special software and supporting equipment. Used to exercise the product in the configuration stated above.
• Determine how long you realistically expect the set-up time. including the physical configuration, support equipment and software.
• As per any general health and safety requirements, you must declare any health and safety related issues. Such as hazardous materials etc. The testing laboratory will either have to decline the project. Or may ask in assisting in making and taking precautions is deemed necessary.

Technical information required for a test plan that should be completed by the manufacturer or importer

• Transmitter information if a wireless radio module is incorporated or used. This may include information on existing modular radio approvals.
• The lowest and highest internal frequencies used within the product. The highest internal frequency used within the product is generally considered to be any frequency used within. But may also include any wireless radio communication module or component. The lowest frequency is usually only required when testing a wireless radio product.
• Determining the operating mode of the product and configuration for emissions testing. Some standards specifically detail the loading conditions. Such as power supplies etc in accordance with EN 55014. Other standards basically define that all the ports should be exercised. By using with a typical stimulus on each port using a typical cable type and length attached in order to fully load and operate the product. This may include a colour video test pattern with moving element for EN 55032. This is in order to exercise the graphics processing unit (GPU). Or applying an audio tone to the audio ports. For many products, it may be desirable to perform pre-compliance EMC testing. To determine the worst case mode, cabling arrangement prior to formal testing. Ethernet traffic is usually well defined in the standard on how to configure the port. It usually relies upon either determination of the worst date rate. Using a fixed 10Mbps rate and utilization of more than 10% traffic on the Ethernet port consisting of typical or pseudo-random data.
• The operating mode of the product and configuration for immunity testing. Typically the mode of operation for immunity testing shall allow the products full functionality. Observed and confirmed to be operating in its normal mode of operation. If the time it takes to allow determination if the immunity testing has affected the product then this may lead to increase testing time and cost. The time to complete all operations and allow observation of any failures is known as the cycle time.
• Confirm with the compliance laboratory how long the product must operate for in the particular mode of operation. Typically for emissions and immunity, this will be more than 2 to 3 hours minimum for each test.
• The distributor usually has to specify performance criteria or an acceptable loss of performance. In the instance where the performance criteria are not defined in the standard. The method of recognizing, watch and report failures must be defined. Along with the definition of failure i.e. the product display becomes pix-elated and longer responsive, i.e. the moving element stopped.

How to write an EMC Test Plan – The information that you may need help from the testing laboratory of Technical Certification Body:

• If any special product requirements. Such as non-standard power requirements or any equipment such as audio analyses, 3G base station simulators. These must be confirmed for availability with the EMC testing laboratory.
• Declaring the intended environment. May include Basic, Industrial or Controlled EM environments. This is usually declared by the customer. But, the customer must fully understand the exact definition of the class and the intended environment of the product.
• Product emissions limits i.e. Class A, Class B etc (if applicable). This is usually declared by the customer. Yet, the customer must fully understand the exact definition of the class and the intended environment of the product. This can also impact the product labelling requirements.
• Required standards and applicable tests that are listed in the standards. This is based on the product and the intended environment. Usually, this can be determined by looking at either the accepted EMC standards. Either in the CE EMC directive Official Journal or the RCM accepted standards list. Or applying the FCC/IC standards, depending upon which is the intended market.

EMC Bayswater is a  NATA accredited EMC testing facility in Melbourne. Equipped with state-of-the-art EMC test chambers. Experienced test engineers helping you achieve compliance and reducing market lead time. We can help you with how to write an EMC Test Plan and answer some of the questions you may have.