Overview of Bulk Current Injection Testing SAE J551 Part 13 (Vehicle) SAE J1113 Part 4 (Component) Presented by Craig Fanning Elite Electronic Engineering Inc. 2006 Automotive EMC Standards Workshop January 30 & 31, 2006 Dearborn, Michigan USA
Overview • Scope SAE J551-13 specifies Bulk Current Injection (BCI) test methods and procedures for testing the electromagnetic immunity of electronic components for passenger cars and commercial vehicles. SAE J1113-4 specifies Bulk Current Injection (BCI) test methods and procedures for testing of the electromagnetic immunity of electronic components before they reach the vehicle. • The electromagnetic disturbance is limited to continuous narrow band electromagnetic fields in the frequency range of 1 MHz to 400MHz. • Corresponding International Standards ISO 11451-4 is an equivalent standard to J551-13 ISO 11452-4 is an equivalent standard to J1113-4
Overview • Applications: • J551-13 provides an alternative means of coupling RF energy to the electrical system of vehicles. It is particularly useful for: • Large Vehicles that may not fit into test chambers. • A Diagnostic Tool for evaluating susceptible modules/systems in the assembled vehicle. • J1113-4 provides a means of coupling RF energy to the harness of a component in a laboratory environment. This method is preferred by many OEM’s for evaluation of components in the 1 MHz to 400 MHz frequency range.
Differences from International Standards • SAE J551-13 adopts ISO 11451-4 • SAE J1113-4 adopts ISO 11452-4 • Currently both the SAE and ISO (vehicle and component) BCI standards are very similar. Like SAE standards, ISO standards are on a continuous improvement cycle. If International Compliance is of concern, be sure to consult the international standards when generating the test plan prior to test. • The FPSC for both SAE standards are in accordance with the concepts of SAE J1812.
Revision OF Standard • SAE J551-13: • The original publication of SAE J551-13 was March 1994. • The SAE J551-13 document was revised and published again in June 2003. • SAE J1113-4: • The original publication of SAE J1113-4 was February, 1998. • The SAE J1113-4 document was revised and published again in April, 2004.
Additional Information and Clarifications • Both specifications provide two methods of performing the test: • Substitution Injection Probe Method • Monitor Current Probe Method • The Substitution Injection Probe Method is be the preferred method. Most of the Automotive OEM’s are specifying the Substitution method for component BCI testing. The Substitution method is also the preferred method of ISO specifications. • If the Monitor Current Probe Method is specified, the injection probe characteristics must also be specified. Since input power to the injection probe is a limiting factor for the test, the injection probe characteristics must be specified in the test plan… otherwise results will vary.
Additional Information and Clarifications • Substitution Method: • J1113-4: • Revised for Forward power measurement only. • Both Common Mode (grounds within the injection probe) and Differential Mode (power and signal grounds outside injection probe below 30MHz) testing is discussed in the revised document. This should be specified in the test plan. • J551-13: • The forward power and net power required to achieve the test current during characterization in the 50 ohm fixture needs to be recorded. • During application of the interfering signal to the DUT harness, be sure to limit the forward power to an increase of no more than 2dB over the forward power level established during the 50 ohm fixture test current level characterization. Without limitation on forward power during test of the DUT, the DUT and cable influences may require very large amounts of forward power to achieve the required NET test power. The limiting of forward power to an increase of no more than 2dB avoids over testing of devices.
Additional Information and Clarifications • Ohms law, simple calculations and conversions are used to determine the level required on the Spectrum Analyzer during the test current level characterization into a 50 ohm fixture (Figure A2). • Example: Test Current = 100 mA • V on SA = 0.1 A x 50 ohms = 5 V • 20 log 5,000,000 uV = 134 dBuV • Measurement system cable loss and external attenuation between 50 ohm fixture and SA must be accounted for: Example: 134 dBuV – 20 dB (atten) – 2.3 dB(cbl loss) = 111.7dBuV • if SA (or PM) reads in dBm (111.7dBuV-107 = 4.7dBm).
Additional Information and Clarifications • Since actual current applied to DUT harness is not measured during substitution method tests, threshold levels reported are calculated currents. This calculated threshold current is based upon test current, power level required for test and power level measured at DUT response threshold. • Example: Test Current = 100 mA = 100,000 uA • 20 log 100,000 uA = 100 dBuA • Forward Power level measured at DUT response threshold is 6dB below test power level. • 100 dBuA – 6 dB = 94 dBuA. • LN (94/20) = 50,118 uA = 50 mA = Threshold Level
Additional Information and Clarifications • Selecting a Test Level: • Test Severity Levels in the standards are suggested. • Most automotive OEM’s, US Military and Aerospace (DO-160) specifications do not require a flat current limit across the applicable frequency range for component testing. A test level of 100mA may be somewhat high at 1MHz. Most items with a communications bus will not be able to operate at the 100mA requirement at 1MHz. A component test level used by some automotive OEM’s is shown on the next slide of this presentation. OEM’s looking for a BCI test current limit may want to consider using this limit. • Modifying the suggested test levels of the standards may be a project for the next revision of the standards.
Future Trends • SAE EMC standard revisions are typically on a 5 year rotation. • J551-13 was revised and published in June 2003. The next revision of this standard most likely begin again in 2007. • J1113-4 was revised and published in April, 2004. The next revision of this standard most likely will begin in 2008. • A major change of international standards may justify an earlier revision. • Possible Changes: • Forward power measurement only? • Cleanup Figure A2 (J551-13) • Show examples for calculations? • New Test Limits? • Extend upper frequency limit to 1000 MHz? • Questions? Comments? Changes requested by Audience?