A pulse transformer transmits rectangular electrical pulses.  A pulse transformer needs to have low values of leakage inductance and distributed capacitance, and a high open-circuit inductance to reduce distortion of the pulse shape. A low coupling capacitance between the primary and secondary is necessary to protect the circuitry on the primary side from high-powered transients created by the load. For the same reason, high breakdown voltage and high insulation resistance and are necessary features of a well-designed Pulse Transformer