Abstract: Automatic reclosing apparatus for a DC feeder circuit breaker connectable between a main power bus and a feeder line, including a transducer connectable to the feeder line and a return bus for producing an output signal that corresponds to voltage on the feeder line; and a programmable controller connectable to the breaker for reclosing the breaker when a fault condition is absent and for preventing breaker closure when a fault condition is present; the controller being coupled to the transducer for detecting zero offset and full scale calibration of the transducer output signal. The apparatus can also determine negative return voltage and use such determination to improve accuracy of a load measurement test. The zero offset and full scale calibration functions can be used to implement open and short circuit tests of the apparatus.

Abstract: An adjustable dielectric bus support clamp with a liner has a duct sidewall for adjustably supporting dielectric clamps which support high current capacity electrical conductors. A resilient dielectric liner fits between the dielectric clamp and the electrical conductor to fill high potential voids and provoide corona damping, while at the same time allowing different sized liners to be used with different sized conductors.