This SAE Standard establishes a common basis for the evaluation of devices and equipment in vehicles against transient transmission by coupling via lines other than the power supply lines. The test demonstrates the immunity of the instrument, device, or equipment to coupled fast transient disturbances, such as those caused by switching of inductiveloads, relay contact bouncing, etc. Four test methods are presented – Capacitive Coupling Clamp, Chattering Relay, Direct Capacitor Coupling, and Inductive Coupling Clamp.1.1 Measurement PhilosophyYears of experience with immunity testing of instruments, devices, and equipment shows the need for tests simulating transient coupling phenomena covering a wide range of electric and electromagnetic disturbances on non-supply leads.The knowledge of these facts is common among EMC experts, and many companies have developed such coupling tests.1.1.1 Capacitive Coupling Clamp (CCC)The fast transient test uses bursts composed of a number of fast pulses, which are coupled into all lines other than the supply lines of electronic equipment. The short rise time, the repetition rate, and the low energy of the transients aresignificant for the test.Theoretical and practical examinations of capacitive and inductive coupling test procedures for car electrical systems with respect to coupling via lines other than the supply lines have been made. Since in the actual test situation neither theoriginal cable harness nor the possible sources of interference are available, worst case testing must be performed which is represented by capacitive coupling. The coupling clamp can be used to couple these fast transients to the DUT via thetest harness.1.1.2 Chattering RelayIn an actual vehicle, inductive transients are usually random in occurrence, amplitude, and duration. Other methods of testing using commercial test instruments that create a very repeatable event are much less effective at finding certaintypes of concerns since they do not create such a random sequence. This randomness is extremely critical for DUTs containing microprocessors since the transients must often line up in time with a certain point in software execution tohave an effect. To create such a match using commercial transient generators takes an unreasonable amount of test time. The noise created by this test is designed to provide a continuous series of random transients using a chatteringrelay.1.1.3 Direct Capacitor CouplingThe Direct Capacitor Coupling (DCC) method uses a capacitor to directly couple both fast and slow transients dependingon the capacitor used. When using the DCC method, care has to be taken to ensure that signals are not unacceptably distorted (e.g. communication on bus systems). For the fast transient test, the disadvantage of the DCC method is thateach line is tested individually unlike the Coupling Clamp method.1.1.4 Inductive Coupling ClampThe Inductive Coupling Clamp (ICC) method uses the Bulk Current Injection components to apply the test pulses. The method is able to better couple the slow transient test pulses. For DUTs with a moderate or large number of lines to be tested, this method has an advantage over the DCC method.