Electromagnetic Compliance of Electronic Products Assessment - Case Study Example

Running Head: EMC of Electronic Products Assessment EMC of Electronic Products Assessment Insert Name: Tutor: Introduction In today's expanding high-technology environment, technology product architects and designers are continuously being challenged by the issues of electromagnetic interference. This is because is not just because of ensuring that their products achieve optimal performance but also to achieve compliance with the current rigorous Electromagnetic Compliance (EMC) requirements. This is report is a guide to the process of certification and appropriate testing methods for an emergency evacuation alarm system. Certification is an independent demonstration that a particular product has been assessed for conformity with accepted standards for safety, quality, performance, et cetera by an industry leader. This will in turn ensure that the manufacturer’s factory is at the same time being assessed to make certain continuing compliance. Electromagnetic Compliance (EMC) requirements EMC is the study of the inadvertent production and reception of electromagnetic energy. It aims to ensure the proper functioning of different electrical and electronic apparatus in the same environment. All electrical and electronic products have an electromagnetic phenomenon in their working. EMC Emissions is related to the cutback in the inadvertent production of electromagnetic energy, while EMC susceptibility or immunity refers to the correct operation of electrical and electronic equipment in the presence of electromagnetic disturbances. Electromagnetic Compliance (EMC) requirements are a legal requirement to all electrical and electronic manufacturing companies as per the Electromagnetic Compatibility Regulations 2005 (Statutory Instrument 2005 No. 281) for the implementation of the Electromagnetic Compatibility Directive 89/336/EEC (the EMC Directive) which were incorporated into UK laws. In the repealed requirements as at 1 January 1996 it applied to; most electrical and electronic products made or sold in the United Kingdom, including imports, must: be so constructed that they do not cause excessive electromagnetic interference and are not unduly affected by electromagnetic interference;in the case of certain radio-transmitting equipment, be subject to EC type-examination by a notified body; and Carry CE marking. In some cases a technical construction file must be drawn up and kept available, generally by the manufacturer or the importer of a product from a non-European Economic Area (EEA) country. EMC Regulations cover all electrical and electronic apparatus liable to cause electromagnetic disturbance or the performance of which is liable to be affected by such disturbance. An is a product, with an built-in utility intended for the end user or customer, and supplied or intended for supply, or taken into service, or intended to be taken into service as a single commercial unit. Electromagnetic disturbance is any electromagnetic phenomenon which may corrupt the performance of the apparatus. An electronic disturbance may be, for example, an electromagnetic noise or unwanted signal, et cetera. All electromagnetic frequencies involved and all electromagnetic phenomena as set out in EMC Regulations. A signal or emission which is a required function, or a consequence of the operation, of applicable apparatus shall not be taken to be electromagnetic disturbance if, in relation to that apparatus, that signal or emission is permitted and does not exceed the limits specified by: the applicable EMC standard; or a condition of a technical report or technical certificate issued by a competent body for the purposes of a technical construction file; or a condition of an EC type-examination certificate issued by a notified body as in the case of radio communications transmitting equipment.For the purposes of the EMC Regulations the performance of apparatus which must comply is taken to be degraded if any of the following types of interference with its function occur : permanent, temporary or intermittent total loss of function or significant impairment of function; or where the apparatus is information storage or retrieval equipment, the destruction or corruption of the information so stored. Protection requirements are the essential requirements, being that apparatus shall be so constructed that, the electromagnetic disturbance it generates does not exceed a level allowing other relevant apparatus to operate as intended; and it has a level of intrinsic immunity which is adequate to enable it to operate as intended when it is both properly installed and maintained, and used for the purpose intended. Whether the level of intrinsic immunity is adequate is to be considered having regard to all the circumstances of the case, and in particular to the level of performance reasonably expected of that apparatus having regard to its function or intended function; any specification for an acceptable level of degradation of performance provided by the manufacturer to the end user; the consequences of degradation of performance provided that nothing shall authorise a level of intrinsic immunity which could permit the operation of the apparatus to be dangerous in any reasonable foreseeable circumstances. The information required to enable use in accordance with the intended purpose of the relevant apparatus must be contained in the manufacturer’s instructions accompanying the apparatus. EMC compliance is beneficial to manufacturing companies. It is a demonstration to their customers and authorities that their products are compliant with EMC regulations. EMC consultants whether internal or outsourced from a service provider offer advice on future products architecture and design, and finally performing an independent technical assessment on a product and ensuring future production matches the certified design, is known to result in enhanced customer assurance , and consequently smaller number of field incidents and recalls. EMC requirements exist for just about all electronic systems. It is a government legal requirement as per Electromagnetic Compatibility (EMC) Directive (2004/108/EC) that came into force on 20 January 2005 in the European region. Most electronic products manufacturing companies have EMC as a part of product performance requirements. To ensure Compliance various standard test methods and subsequent data review are used. Electromagnetic Compatibility (EMC) Test Plan Electromagnetic compatibility (EMC) test plan is a detailed guide that the manufacturer uses to ensure that all conformity tests have been done. It is an output of various factors and is developed after an intensive needs analysis. This analysis involves surveying the environment where the product will be required to function and predicting the kinds of stresses the product will be subjected to for example EMC, EMI, heat, cold, vibration, After the analysis protection and testing requirements are developed based on findings of the needs analysis, and finally training of designers and engineers on the compliance standard requirements and strategies for achieving these requirements. They are also trained on design review and analysis, implementing any necessary design changes and establishing standard test procedures. Below is a test plan components for an electronic alarm system. This product has been assumed to be fit for the purpose and is installed in a busy shopping mall. Here we refer to the product as Equipment under Test (EUT). 1. EUT Documentation; this section provides the necessary documentation for detailing the Equipment under Test (EUT). A description of the equipment including software and documentation on installation and operations is provided. 2. EUT Type & Description: Electronic alarm System Description Model Number Serial Number FCC ID Number 3. Operating modes: 4. EUT I/O Ports and Cables: Connection: Shield: Connectors: Termination Type: Length: Removable: 5. Power Cords Unit: Manufacturer: Shielded: Length: Other factors that are considered as part of EMC test plan requirements. 6. Oscillator Frequencies 7. Power Supply 8. Power Line Filters 9. Critical EMI Components (Capacitors, ferrites, etc.) 10. Description of Enclosure: (including Gasketing, Coatings, Bonding, etc.) 11. Interfacing and/or Simulators Peripheral Equipment EMC Testing procedure and equipment In the past EMC testing emphasized on system level evaluations but currently the focus is moving to component level requirements and performance. In whatever case or approach used the devices are required to be identified as meeting the requirements. The diagrams below show the alarm system or Equipment under Test (EUT) and its wiring connection block circuitry. The first diagram illustrates Radiated Emissions measurement using an antenna while in the second diagram we have Conducted Emissions (CE) measurement wiring using a receiver. Immunity test is performed to allow the compatibility of the electronic system with the environment. Radiated and Conduction emission testing diagram; In a retail store or shopping mall environment we find very many other sources of signals for example from customer cell phones and wearable portable devices, equipments and electronic devices in use in the shopping mall . This is illustrated below in the diagram. Today’s (Radio Frequency) RF environment especially in crowded areas like retail and shopping malls, in stadiums and theaters consists of both high power remote sources and lower power local sources. The majority of the remote sources expose an apparatus to low to medium Electromagnetic fields. At times a number of low power local sources generate Electromagnetic fields that are much larger than the higher power remote sources. Electric field strength is calculated in terms of Volts per meter and is function of transmitter power, antenna gain, and distance from source. It is assumed that the alarm system product has inherent design in properties appropriate for the immunity characteristics based on the expected RF environment that the alarm system will be subjected to. System and component testing will be done by simulating external sources to make certain immunity characteristics. As a process of testing the Alarm system Electric Field strength, a circuit board is located 10 meters from a rooftop antenna transmitting at certain power for example 1000 watts. The electric field strength would then be calculated. Immunity Testing test set-up similar to emissions testing. The Alarm system or EUT is set up in the normal operational situation; RF energy is then radiated to the test set-up. Direct connection to EUT may also be implemented as shown in the diagram below. Other methods used include the Bulk Current Injection (BCI) test method which involves the introduction of RF or pulsate energy on wiring attached. The results obtained are expressed in Decibels or dB. The following test methods are recommended for an alarm system to be used in a busy or crowded environment like a shopping and retail malls. Test 1: Effects due to wiring: The alarm system is put into its operational modes, power wires and signal lines are moved and observations made for any unanticipated conditions that may occur. Several observations are made for example system Input/output changes that can be recognized by the test equipment and change the effect of scrounging inductive or capacitive coupling characteristics from the wiring. Test 2: Radiated Emissions and Radiated Immunity Quick Test. The alarm system is set up into operational mode and a portable radio is used to spot emissions. Both AM and FM radio receivers are used. The AM receiver settings are used to trace BB noise while the FM settings are useful to trace NB noise. Clamp ferrites on harnesses are used to reduce the effect of conducted energy. To test for immunity handheld electronic test transmitters provide local high fields that enable identification of potential issues. Test 3: Shielding limited to small areas is used to enhance immunity to Electromagnetic fields. It consists of a shield for the electric field vector and is done with a ferrite for magnetic field induced currents on the wiring. It is used as a diagnostic step to determine a particular susceptible element or cable sometimes integrated into a design as an essential component to satisfy EMC requirements. EMC initial diagnosis and analysis can be accomplished by using common items found in modestly equipped electrical and electronics lab. The objective is to carry out basic tests to spot the source –path - receiver present in every EMC problem. Examples of such tools include an electricians multi-tool that has the capability to slice wire and take out paint and corrosion, the use of a measuring tools like tape measure that help to spot wires that may act as undesired antennas because of their length . Other test equipment will include an electricians Voltage, current, and continuity measurements meters for measurements of wire resistance and conductive assemblies. Conclusions EMC testing is an essential part of producing“EMC compliant” product. Test methods are defined to identify emissions, immunity sensitivities, and effects of system interactions.Pre-compliance testing can be used as a first indicator of EMC performance. Final EMC testing is accomplished according to test specifications using high quality instruments. References Morgan, D. 2007, A Handbook for EMC Testing and Measurement, Institute of Engineering and Technology, London: United Kingdom. 2005. The Electromagnetic Compatibility Regulations 2005. [Online]. Available from: http://www.opsi.gov.uk/si/si2006/20050281.htm [Accessed 11/20/2009]. Read More