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US 4,061,963 AGranted
Load tap changer system
AssigneeWestinghouse Electric Corp.
InventorJohn W. Green
Life of this patent
Estimating the term…
Abstract
A load tap changer system for electrical power transformers, including protective apparatus which prevents a tap change in the event of a malfunction during a tap change cycle. The protective apparatus includes a relay and a current responsive device for operating the relay when current is flowing at a location prior to a tap change which would not have current flow during a normal tap change cycle. Current applied to the relay is maintained within the operating range of the relay by a tapped transformer operated by the tap changer drive.
Claims7
A load tap changer system, comprising:
- tap selector switching means having contact arms selectively movable between a plurality of electrical contacts, said plurality of electrical contacts being adapted for connection to taps on an electrical winding disposed to supply current to a load circuit,
- drive means for operating said tap selector switching means during a tap change cycle,
- means for electrically isolating each contact arm prior to movement thereof by said drive means,
- current transformer means disposed to measure current flow through the contact arm to be moved during a tap change cycle, prior to movement thereof by said drive means,
- protective means responsive to said current transformer means for preventing said drive means from moving a contact arm which has current flowing therethrough,
- means connected between said current transformer means and said protective means including a tapped transformer having switch means connected to said taps, said switch means being operated in response to said drive means for providing current to said protective means, when said current transformer means is providing an output, which is within the operating range of the protective means regardless of which taps on said electrical winding are connected in said load circuit.
3 more elements
A load tap changer system, comprising:
- tap selector switching means having contact arms selectively movable between a plurality of electrical contacts, said plurality of electrical contacts being adapted for connection to taps on an electrical winding disposed to supply current to a load circuit,
- drive means for operating said tap selector switching means during a tap change cycle,
- means for electrically isolating each contact arm prior to movement thereof by said drive means,
- current transformer means disposed to measure current flow through the contact arm to be moved during a tap change cycle, prior to movement thereof by said drive means,
- protective means responsive to said current transformer means for preventing said drive means from moving a contact arm which has current flowing therethrough,
- means connected between said current transformer means and said protective means including a tapped transformer and switch means connected to said taps, said switch means having make-before-break contacts, said switch means being operated in response to said drive means for providing current to said protective means, when said current transformer means is providing an output, which is within the operating range of said protective means regardless of which taps on said electrical windings are connected in said load circuit.
3 more elements
Dependencies are inferred from the claim text.