Immunity to electrical fast transients (burst) - 5/50 ns pulses, levels 0.25–4 kV.
The standard specifies a method for testing equipment immunity to repetitive electrical fast transients (EFT/burst) on power, signal, control and earth ports. It simulates disturbances caused by switching processes such as interruption of inductive loads and relay contact bounce.
In rolling stock and infrastructure, such pulse bursts occur whenever contactors, relays and solenoid valves supplied from the same onboard network operate.
The test demonstrates that equipment withstands pulse bursts at a specified voltage without damage and with defined functional behavior; it provides a consistent method for comparing immunity of different devices. The method number is not a declaration of conformity; test voltage, repetition frequency and performance criterion are selected by the product or generic EMC standard.
The generator produces pulses with 5 ns rise time and 50 ns width (into 50 Ω), grouped into bursts: at 5 kHz a burst lasts 15 ms, at 100 kHz 0.75 ms, with a burst repetition period of 300 ms. For power ports, pulses are coupled through a coupling/decoupling network with 33 nF capacitors; for signal and control lines, through a capacitive coupling clamp in which the cable is routed over 0.5 m (tabletop equipment) or 1.0 m (floor-standing equipment).
The equipment under test is placed on a reference plane on a 0.1 m insulating support. Test duration must be no shorter than the time needed for the equipment to respond and in no case shorter than 1 min. Results are assessed in four categories: normal operation; temporary degradation with automatic recovery; temporary loss requiring intervention; irreversible damage.
Check the test voltage separately for the power port and signal ports (e.g. 2 kV / 1 kV corresponds to level 3) and the performance criterion. The railway EMC standard (EN 50121 series) references this method with its own levels.
