The impulse strength of lapped impregnated paper dielectric

An investigation of the impulse strength of lapped impregnated paper dielectric has been made using model cables. The subjects studied include the effects of variation in the physical properties of the paper and the impregnant, the effects of variations in construction of the dielectric, and the effects of temperature and pressure. In addition, the response to different test procedures, such as polarity, polarity reversal and repeated stressing, has been examined. The breakdown process, with impulse voltages, is discussed in the light of the results obtained. Both components¿the paper and the oil¿are shown to be effective in determining the impulse strength of the composite dielectric.