Transient immunity generators simulate transients for EMC testing purposes. Specifically, a transient test system is essential for the conducted immunity portion of EMC testing. A transient is a dramatic fluctuation in current or voltage a device may experience while connected to a power grid. Voltage spikes and oscillations are common examples. Conducted immunity testing will determine the immunity the equipment under test to such disturbances. To test a device’s immunity to transients, a generator or immunity test system will reproduce transients like those found in the field.
Real world causes of transients include indirect lightning, which may strike nearby and send a surge through a grid. The electricity travels indirectly through wiring, causing electrical and electromagnetic interference. Another source of transients is electrical switching. Switching refers to when one device on a grid, when switched on, sends a transient to another device on the grid. Waveform variation allows for a transient generator to replicate nearly any transient a device may come across, and most transient immunity testers will include modules for specific waveforms. Many manufacturers rent transient generators for in-house use to simulate the same waveforms a test lab will, so they can pass their product through in a timely manner. Specifically, most transient immunity test systems generate waveforms specified by tests corresponding to IEC/EN 61000-4 test standards.
Commercial Conducted Immunity Test Standards