GJB 298 is the Chinese national military standard specifying the surge voltage test methods that apply to the 28 V direct-current electrical systems of military vehicles. The standard corresponds in purpose to the United States military standard for the characteristics of 28 V d.c. electrical systems in military vehicles, and it defines the transient conditions that equipment connected to such a system must tolerate. The 28 V system of a military vehicle is exposed to severe transients: the interruption of a large inductive load produces a negative voltage spike, the disconnection of a heavily loaded alternator while the engine is running produces a load dump whose amplitude and duration depend on the alternator and the battery condition, and the switching of relays and contactors produces repetitive fast transients. The standard defines the waveform, amplitude, duration, source impedance and repetition of these surges and the test arrangement in which they are applied to the equipment, so that a component can be qualified against the vehicle environment in a repeatable way.