Robert Gerald Graf

US Patent:

41539230, May 8, 1979

Filed:

Feb 15, 1977

Appl. No.:

5/768743

Inventors:

Robert G. Graf - Bluefield WV

International Classification:

H02H 510

US Classification:

361 48

Abstract:

A system for monitoring the continuity of at least the ground wire of a cable connected between a mining machine and a power center. At the power center, a monitor signal is coupled to multi-phase power conductors of the cable through a multi-phase filter. The monitor signal from the conductors is coupled to the ground wire at the mining machine through another multi-phase filter. The signal returns through the ground wire to the power center where a current transformer couples the signal from the ground wire to a receiver. The receiver which receives and senses the characteristics of the returned signal includes parallel phase locked loop discriminators to prevent false tripping of the main power breaker if the monitor frequency should vary only slightly. The parallel discriminators provide a fail safe arrangement to prevent the main power breaker from remaining closed if one of the parallel discriminators should malfunction. A decrease in amplitude or change in frequency beyond a pre-selected range of the monitor signal at the receiver discontinues the receiver output so the main power breaker will open and cut off the A-C power to the mining machine.

US Patent:

20140211377, Jul 31, 2014

Filed:

Jan 29, 2014

Appl. No.:

14/167367

Inventors:

- Rocky Gap VA, US
Robert GRAF - Rocky Gap VA, US

Assignee:

AMERICAN MINE RESEARCH, INC. - Rocky Gap VA

International Classification:

H02B 11/133

US Classification:

361609

Abstract:

A removable contactor drawer including a transitional chamber receivable in a fixed casing. The transitional chamber including electrical components for an electrical feeder circuit. The fixed casing being designed to be mounted and used within a power distribution center and has input connectors for the incoming electrical power. Source power may be channeled through the electrical components via the fixed casing and delivered to a power outlet on a front face of the transitional chamber. The transitional chamber may optionally contain equipment to monitor and report operational faults within the contactor drawer. A front-mounted motor drive allows a remotely located operator to perform removal of the transitional chamber while under power, thus providing protection against the danger of arc flash.