. . . "The very short duration of a pulse (less than 1 ms, e.g. 0.5 ms), coupled with the energyused to generate this pulse, produces a relatively high instantaneous power of the order of 1 to 2 kW. As an additional protective measure, and by way of example, we plan to use a transformer with a 50 V insulation for the winding P.sub.2 (for itssupply of only 24 V), a 500 V insulation for the winding (P.sub." .