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1. US5671110 - Ground skew protection method and apparatus

Office
United States of America
Application Number 08589980
Application Date 23.01.1996
Publication Number 5671110
Publication Date 23.09.1997
Grant Number 5671110
Grant Date 23.09.1997
Publication Kind A
IPC
H02H 3/00
HELECTRICITY
02GENERATION, CONVERSION, OR DISTRIBUTION OF ELECTRIC POWER
HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
3Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition, with or without subsequent reconnection
H04B 3/02
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
BTRANSMISSION
3Line transmission systems
02Details
H04B 3/30
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
BTRANSMISSION
3Line transmission systems
02Details
30Reducing interference caused by unbalance current in a normally balanced line
CPC
H04B 3/30
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
BTRANSMISSION
3Line transmission systems
02Details
30Reducing interference caused by unbalance current in a normally balanced line
Applicants Oneac Corporation
Inventors McCartney Thomas
Fish Laurence H.
Agents Mason, Kolehmainen, Rathburn, & Wyss
Title
(EN) Ground skew protection method and apparatus
Abstract
(EN)

A method and apparatus are provided for protecting a non-isolated data communications cable against ground skew used with an AC power source. A current summing transformer is coupled to an AC power source. The current summing transformer includes a single transformer core and a plurality of coils. One of the coils is connected in series with each phase, neutral (if present) and ground line in the AC power source. The plurality of coils are substantially identical. Each coil has an identical number of turns and an identical direction of winding on the transformer core. The current summing transformer is only needed in the power path to one of two or more interconnected systems. The current summing transformer introduces a high impedance to surge current in the data cable ground of one or many non-isolated data cables attached to the system and at the same time offers substantially zero impedance to the normal power currents including leakage and fault ground currents.