Electricity: power supply or regulation systems – External or operator controlled – Using a transformer or inductor as the final control device
Patent
1989-12-06
1991-04-09
Beha, Jr., William H.
Electricity: power supply or regulation systems
External or operator controlled
Using a transformer or inductor as the final control device
361 9, 361 13, H01F 2904
Patent
active
050067842
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a new and improved arrangement in an on-load change-over switch of an on-load tap changer for uninterrupted switch-over of the regulating winding of a transformer.
In its more particular aspects, the present invention specifically relates to a new and improved arrangement in an on-load change-over switch of an on-load tap changer for uninterrupted switch-over of the regulating winding of a transformer and wherein the on-load current can be conducted via a lower or higher winding tap of a regulation stage of a regulating winding and through a connection of at least two selector contacts and two permanent contacts with a common output line. Furthermore, the switch-over from the lower to the higher winding tap or vice versa is effected via a first change-over switch in a manner such that the on-load current briefly changes over to a load relief circuit which is arranged between a root connection of this first change-over switch and the common output line. Furthermore, a respective one of the two contacts of the first change-over switch is applied to the connection of one selector contact with on permanent contact.
The uninterrupted on-load change-over switching under voltage in tapped transformers is usually carried out by means of mechanical switching elements. The regulating winding to be switched possesses taps connected to a selector which selectively applies the taps to the common output line by means of the on-load change-over switch.
The switch-over is always effected between neighboring taps, i.e. by one step each time. For this purpose, at first the desired tap is preselected by means of the selector. The on-load change-over switch thereupon carries out, under temporary interconnection of transition resistors, the switch-over of the current from the selected tap to the preselected tap. In both end positions the transition resistors are not loaded because they are shunted by the main contacts of the on-load change-over switch.
The selector and the on-load change-over switch are usually accommodated in the transformer tank, whereby the on-load change-over switch is located in a vat of its own, the oil filling of the latter being separated by seals from the oil charge of the transformer.
The burning of contacts occurring during switch-over and the sooting of oil due to electric arcs occurring during switching are thereby disadvantageous. Therefore, in order to ensure trouble-free operation the contacts and the oil have to be changed after a certain number of switching operations, so that there occur interruptions in the operation due to the thus caused transformer shutdown.
Furthermore, constructions are known in which on-load change-over switching is accomplished by means of a combination of mechanical switching elements and thyristors. Such a combination is apparent from British Patent No. 1,399,528.
The arrangement as described in British Patent No. 1,399,528, consists of at least two selector contacts and two permanent contacts, a transition resistor as well as a load relief circuit comprising two thyristors connected in antiparallel, two ignition diodes and a thyristor control contact.
The selector consists of two not simultaneously moved single-pole change-over switches, whereby the change-over contacts of one change-over switch are connected with the change-over contacts of the other change-over switch and are applied to the respective taps of a regulating stage of a regulating winding.
From the root connections of the two selectors, one conductive connection leads directly and the other conductive connection leads via the transition resistor to respective root connections of the two permanent contacts.
Via the selector contacts and the permanent contacts there is effected a connection to a common output line either directly or via the thyristor circuit, depending on the switching position.
In the central position the permanent contacts short-circuit the thyristor circuit. The permanent contacts as well as the thyristor control contact
REFERENCES:
patent: 3651375 (1972-03-01), Ebersohl
patent: 3662253 (1972-05-01), Yamamoto
patent: 3786337 (1974-01-01), Kugler
patent: 4081741 (1978-03-01), Palmer
patent: 4301489 (1981-11-01), Stich
patent: 4363060 (1982-12-01), Stich
patent: 4550285 (1985-10-01), Kugler et al.
patent: 4571499 (1986-02-01), Wein
patent: 4622513 (1986-11-01), Stich
Beha Jr. William H.
Elin-Union
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