Question { Essar, 185538 }

What are the difference between C-Curve and D-Curve for
MCB's.

Answer

B curve 4x In
c curve 7.5x In
d curve 10x In
c curve is used in most house switchbords. d curve is used where in rush currents are a problem ie motors that do not have soft starting.

Question { Alstom, 26076 }

what is the function and use of oil filled cables specify
its advantages and disadvantages

Answer

use of oil filled cable are at HV 33kv 66kv 132kv 330kv in
australia 275kv uk and 440kv uk. The oil is in the cable as
it is a good dieletric it also fills the void between the
primary insulation which is paper its also very good at
absorbing gases that are produced at very high voltages.
the life of the cable is very long and this can be
monitored by testing the oil looking for specfic gases that
indicated what is happening in the cable. The oil is
biodegradable its code is T3788 if you want to search this.
Disadvantages is maintenance and xlpe cable production is
improving all the time which is decreasing its losses in
its dielectric.or insulation.