50 KV PULSE CABLE ASSEMBLIES.
Final rept. 1 Aug 61-31 Dec 63,
GENERAL ELECTRIC CO SCHENECTADY NY
Pagination or Media Count:
RG-191U, properly modified and specified, will provide reliable service as a 50 kv pulse cable up to a duty cycle represented by a pulse repetition rate of 500 pps, and a pulse width of 2.5 microseconds. The modifications involve a change in the design of the center conductor to lower the attenuation and minimize the temperature rise in operation and a change in the jacket to provide more adequate life at the worst operating condition. The specifications involved are that the dissipation factor of the dielectric not exceed 0.008 at 125C in the frequency range from 100 kc to 1 Mc, that the cable core be free of corona up to 30 kv rms, and that the finihed cable be free of corona pulses exceeding 20 micro microcoulombs at 20 kv. Satisfactory, reliable service is defined as less than 10 of cable failures in service before a service life of 60,000 hours at the duty cycle mentioned. Here it is assumed that the average cable length is 20 feet. Investigation showed that either with high loss butyl rubber compound or with inadequate cure, the RG-191U cable was susceptible to thermal failure. It is possible to select the compound and the cure to avoid this. Investigation also showed that failure by a corona initiated mechanism was unlikely. This was unexpected and indicates that at the voltage lovel of the test the corona was either sporadic in nature or self-healing. Author