Apparatus for protecting vacuum interrupter type on-line tap changer
First Claim
1. A vacuum interrupter type on-line tap changer comprising:
- a plurality of current switching elements, each of said current switching elements being coupled to a corresponding tap of a transformer through a lead wire;
a plurality of vacuum interrupters and a current limiting resistor, said vacuum interrupters and said current limiting resistor being coupled to said current switching elements so that a cross current can flow selectively through said current limiting resistor and said vacuum interrupters in accordance with contact positions of said current switching elements;
a plurality of current transformers, said current transformers being disposed to sense a current in said lead wires;
a plurality of current detecting relays and overcurrent relays, one of said current detecting relays and one of said overcurrent relays being provided for each of said current transformers, said current detecting relays and said overcurrent relays being operatively coupled to a corresponding current transformer, each of said overcurrent relays having a contact for interrupting current flowing in said transformer.
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Accused Products
Abstract
An apparatus for protecting a vacuum interrupter type on-line tap changer in which a cross current flows between taps through a current limiting resistor for a predetermined time by shorting selected taps therebetween at the time of tap changing operations. Vacuum interrupters are employed as current switching elements. A dial switch selects the position of the tap of the tap changer. A limit switch closes only at a predetermined position of the dial switch during tap changing operations. Thus, a cross current between the taps or a load current flowing for a long time due to a drop in the degree of vacuum of the vacuum interrupters is detected, thereby preventing burn-out of the current limiting resistor and damage to contacts of a disconnecting switch due to interruption of the current.
42 Citations
8 Claims
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1. A vacuum interrupter type on-line tap changer comprising:
- a plurality of current switching elements, each of said current switching elements being coupled to a corresponding tap of a transformer through a lead wire;
a plurality of vacuum interrupters and a current limiting resistor, said vacuum interrupters and said current limiting resistor being coupled to said current switching elements so that a cross current can flow selectively through said current limiting resistor and said vacuum interrupters in accordance with contact positions of said current switching elements; a plurality of current transformers, said current transformers being disposed to sense a current in said lead wires; a plurality of current detecting relays and overcurrent relays, one of said current detecting relays and one of said overcurrent relays being provided for each of said current transformers, said current detecting relays and said overcurrent relays being operatively coupled to a corresponding current transformer, each of said overcurrent relays having a contact for interrupting current flowing in said transformer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- a plurality of current switching elements, each of said current switching elements being coupled to a corresponding tap of a transformer through a lead wire;
Specification