US3475574A

US3475574A - Power switch including opposed diodes in circuit with switch contacts

Info

Publication number: US3475574A
Application number: US628674A
Authority: US
Inventors: Walter Stolarz
Original assignee: Bbc Brown Boveri & Cie
Current assignee: BBC Brown Boveri AG Germany
Priority date: 1966-05-26
Filing date: 1967-04-05
Publication date: 1969-10-28
Anticipated expiration: 1986-10-28
Also published as: DE1243757B; SE328623B; FR1532433A; CH436419A

Description

Oct. 28, 1969 w. 'STOLARZ 3,475,574

POWER SWITCH INCLUDING OPPOSED DIODES IN CIRCUIT WITH SWITCH CONTACTS Filed April 5, 1967 5 Sheets-Sheet l Walker SLolar:

Oct. 28, 1969 w. STOLARZ 3, 75,5

POWER SWITCH INCLUDING OPPOSED DIODES IN v CIRCUIT WITH SWITCH CONTACTS Filed April 5, 19s? 5 Sheets-Sheet 2.

Fig. 3

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POWER SWITCH INCLUDING OPPOSED DIODES IN CIRCUIT WITH SWITCH CONTACTS Filed April 5, 1967 5 Sheets-Sheet 5 Oct. 28, 1969 w. STOLARZ 3,475,574

POWER SWITCH INCLUDING OPPOSED DIODES IN CIRCUIT WITH SWITCH CONTACTS Filed April 5, 1967 5 Sheets-Sheet 4 Fig. 6

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28, 1969 w. STOLARZ 3,475,574

POWER SWITCH INCLUDING OPPOSED DIODES IN CIRCUIT WITH SWITCH CONTACTS Filed April 5, 1967 5 Sheets-Sheet 5 Emu 130m \A al cer 5 [Lol arz.

/PW JWAPM United States Patent Office U.S. Cl. 200-144 7 Claims ABSTRACT OF THE DISCLOSURE An electrical power switch for interrupting alternating currents includes a pair of contact members one of which Is stationary and the other movable. At least one auxiliary electrode is arranged perpendicularly to and adjacent the disconnecting path between the contact members and the distance between the auxiliary electrode and the contact members is smaller than the length of the disconnecting path between the contact members when fully disconnected. Diode circuits each including at least one diode extend respectively between each contact member and the auxiliary electrode and these diodes are connected in opposition. Means are also provided for blasting the are drawn between the contact members upon disconnection. The diode circuits in conjunction with the auxiliary electrode and blasting serve to divert the are away from the main contact members by transferring its ends to the auxiliary electrode and movable contact member so that it is quenched more quickly.

The present invention relates to a power switch with oppositely directed diode circuits, each consisting of at least one diode, to facilitate the disconnection of alternating currents in each current direction, and with auxiliary electrodes to which the arc is commutated during the disconnection, as well as with blasting of the arc. To use diodes in connection with power switches for alternating current to quench the arc and thus to facilitate the disconnection, is already known from the German Patent No. 638,981. Here two contacts are provided to each of which is assigned a diode with a different conducting direction. The mode of operation of such an arrangement is that, when both contacts are opened, the current continues to flow in a half wave up to the zero passage point, but then has no more opportunity to flow in the other direction, since the circuit which would just carry current remains then blocked by the rectifier. The other circuit, through which no current has flown before, has then already its full dielectric strength so that no current can flow there either.

It is also known, from Swiss Patent No. 387,738, to determine by means of synchronizers in three-pole switches with parallel diodes the moment when the contacts open. If this moment is just before the zero passage point of the current in one phase, the current drops rapidly in this phase to zero and quenches; in the other phases the current is quenched at most after a half cycle.

In switches with parallel-connected diodes it is known, from German Patent No. 1,005,590, to assemble the main contact with arcing horns into which the are formed on the contact is blown. The horns are connected in series with the diodes. In this case the arc commutates, when the current direction is the same as the conducting direction of the diodes, to the spark horn and extinguishes.

The disadvantage of these arrangements is that the contacts must be switched at certain times and in a certain dependence on each other. This requires electrical or 3,475,574 Patented Oct. 28, 1969 mechanical devices which considerably increase the costs of the switch mechanism.

In addition, it has been suggested to provide compressed air switches with auxiliary electrodes to which the arc is commutated by blowing with compessed gas. The auxiliary electrodes are connected in series with diodes so that the arc can quench after commutation. The auxiliary electrode is arranged here inside the nozzle contact. The arc, which burns at first between the main contacts, is commutated to the auxiliary electrode by blasting when the current is just in the conducting direction of the diode.

The disadvantage of this arrangement is that in case the disconnecting order arrives just when the direction of current flow is opposite to the conducting direction of the diode, the arc can burn up to a half cycle before it is quenched. This disadvantage is to be eliminated too, so that the load by burning arcs is further reduced.

According to the invention it is therefore suggested to arrange the diodes between the main contact members of the switch and at least one auxiliary electrode, and to locate the one or more auxiliary electrodes perpendicularly to the contact path of the main contacts, and to make the distance from the auxiliary electrode to the main contact members smaller than the length of the disconnecting path between the main contact members when fully disconnected and to blast the arc in a transverse direction.

Due to this special construction of the electrodes, which is described more fully in the following drawings, it is now possible to apply the known measure of two 0ppositely directed diodes and thus to prevent the are from burning longer between the main contacts.

The foregoing, as well as other objects and advantages will become more apparent from the following detailed description of several suitable embodiments of the invention and the accompanying drawings wherein:

FIG. 1 is a schematic representation of an electrical switch incorporating one embodiment of the invention, and with the switch contacts shown in closed position;

FIG. 2 is a schematic view similar to FIG. 1 but showing the switch contacts in open position;

FIG. 3 is a view in side elevation of the details of the electrical switch as portrayed schematically in FIGS. 1 and 2;

FIG. 4 is a schematic representation of another embodiment of the invention and with the switch contacts shown in closed position;

FIG. 5 is a view similar to FIG. 4 but with the switch contacts shown in open position;

FIG. 6 is a view in side elevation of the details of the electrical switch portrayed in FIGS. 4 and 5; and

FIG. 7 is a schematic representation of still another embodiment of the invention constituting a variant of the construction shown in FIGS. 4-6.

With reference now to the embodiment of the invention illustrated in FIGS. 1-3, the stationary contact member of the power switch is designated by numeral 2, and the movable contact member, which can move towards the right, is designated by numeral 1. The auxiliary and stationary electrode is designated 3 and the two diodes are designated by 4 and 5. While these have been indicated as single diode elements, for the sake of simplicity, it is to be noted that each of these diode paths can include a plurality of series connected diode groups. The auxiliary electrode located laterally of the ends of contact members 1, 2 is so wide that it covers the entire disconnecting path between the two contacts, so that the length of the arc path between it and the movable contact member 1 is, in he disconnected position, smaller than the distance between the two separated contact members. The

3 connection terminals to the switch are designated 6 and 7. The blasting is indicated by the arrows 8 in FIG. 2. This can be effected in known manner, e.g. magnetically or by compressed air.

A magnetic type of blasting arrangement is illustrated in FIG. 3 from which it will be seen that a magnetic field producing coil 15 is provided and which is energized by the current which flows through the switch. This view also shows a release, or tripping out coil 16 which, when energized, causes the switch contacts to open. The pawl for locking the release is indicated at 17.

The operating sequence during disconnection of the switch contacts is as follows: Contact member 1 is moved to the right by the operating mechanism shown in FIG. 3. An are 9 is then formed between the two contact members 1 and 2 as indicated by the wavy line 9. If current flow is in the direction indicated by the arrows applied to terminals 6 and 7, the diode 4 transmits current. An are 10 is then blasted between the auxiliary electrode 3 and the moving contact member 1. The current flows then from terminal 6 over diode 4, and across auxiliary electrode 3 and arc 10 to the moving contact member 1 and thence to the current output terminal 7. After the current zero passage point no current can be formed, neither in one nor in the other direction. It cannot flow in diode 4 because the current would change its direction, and not in diode 5 because there is no longer any closed path between auxiliary electrode 3 and the stationary contact 2, and this path has not been ionized. This path has thus already the full arc-over strength.

If, at the time of the disconnection, the current happens to flow in the other direction, an arc can form by blasting the arc between auxiliary electrode 3 and the stationary contact 2. The current fiows then from terminal 7 over diode 5, through auxiliary electrode 3, and the arc to the contact member 2 and to terminal 6. It extinguishes then likewise at the current zero passage point in the current cycle. This has the result that each half cycle is immediately quenched without synchronizers, and the burning loss can thus be kept to a minimum.

FIGS. 4-6 illustrate an arrangement which prevents the diodes or

diode paths

4 and 5 frqm being stressed by the mains voltage when the switch contacts are open. In this embodiment, the auxiliary electrode is divided into two parts 3.1 and 3.2 and each part is connected respectively with a diode. The two parts are arranged side-by-side, but not touching, in the direction of the movable contact member 1. The auxiliary electrode 3.1 is connected with diode 5, the auxiliary electrode 3.2 with diode 4. The designations are the same as in FIG. 1. FIG. 4 shows the switch in the closed state, FIG. 5 in the open state with the burning arcs 9 and 10 during the disconnection. This subdivision can be carried out since the are between the auxiliary electrode and the main contact member burns either to the right or left, depending on the current direction. One can see in the represented arrangement that the circuit is then closed for the indicated current direction, as indicated in FIG. 1. When the switch is open and an are no longer burns, the mains voltage exists only at the main contact members while the diodes are not electrically connected with each other because of the division of the auxiliary electrode so that they carry no voltage.

FIG. 7 shows an arrangement which keeps the burning loss completely off the main contacts. Rigidly connected with the stationary contact part 2 is a consumption or burn-0E contact 13 located beside electrode 3.1. Above the moving contact member 1 in the disconnecting position of the switch and to the side of auxiliary electrode 3.2 is arranged an additional stationary consumption electrode 14 which is only connected electrically with the moving contact member 1 by conductor 15. The auxiliary electrodes 3.1 and 3.2 are arranged in the same manner as in FIGS. 4-6. The quenching process is similar to that in the arrangement according to FIGS. 4-6 except that the are 10 is blasted from the movingcontact part 1 to between the consumption electrode 14 and auxiliary electrode 3.2 and assumes thus successively substantially the positions 11 and 12. It burns then up to the current zero passage point only between an auxiliary electrode and a consumption electrode. This has the additional advantage that practically no burning loss is any longer possible on the main contact members.

I claim:

1. In an electrical power switch for interrupting alternating currents the combination comprising a pair of disconnectable contact members (2),(1) one of which is stationary and the other movable, at least one auxiliary electrode (3) arranged perpendicularly to and adjacent the disconnecting path between said contact members, the distance between said auxiliary electrode and said contact members being smaller than the length of the disconnecting path between said contact members when fully disconnected, diode circuits each of which includes at least one diode (4),(5) extending respectively between each said contact member and said auxiliary electrode, said diodes being connected in opposition, and means (15) for blasting the are drawn between said contact members upon disconnection in a direction transverse to said disconnecting path.

2. An electrical power switch as defined in claim 1 wherein but a single auxiliary electrode is provided to which are connected both of said diodes, and the width of said auxiliary electrode is substantially equal to the length of said disconnecting path between said contact members.

3. An electrical power switch as defined in claim 1 wherein a pair of auxiliary electrodes (3.1),(3.2) are provided, said diodes being connected respectively to said auxiliary electrodes such that the auxiliary electrode (3.2) located generally opposite the movable contact member 1 when in the disconnected state is connected to the diode (4) in the diode circuit connected to said stationary contact member (2), and the auxiliary electrode (3.1) located generally opposite said stationary contact member (2) is connected to the diode (5) in the diode circuit connected to said movable contact member (1).

4. An electrical power switch as defined in claim 3 wherein said auxiliary electrodes (3.1) and (3.2) are arranged in a generally side-by-side but electrically insulated manner in the direction of movement of said movable contact member (1) along said disconnecting path.

5. An electrical power switch as defined in claim 1 and which further includes stationary consumption contacts (13),(14), one of said consumption contacts (13) being rigidly connected with said stationary contact member (2) and the other (14) being connected electrically by means of a conductor (15) with said movable contact member (1), the distance between said consumption contact (14) and said movable contact member (1) when in the disconnected state being smaller than the arc-over path between said auxiliary electrode (3.2) and said movable contact member (1).

6. An electrical power switch as defined in claim 1 wherein said means for blasting the are drawn between said contact members is constituted by means producing a magnetic field.

7. An electrical power switch as defined in claim 1 wherein said means for blasting the are drawn between said contact members is constituted by means producing a blast of air.

References Cited UNITED STATES PATENTS 2,729,723 1/ 1956 Pristsak 200147 2,782,345 2/1957 Kesselring 317--11 3,293,496 12/1966 Induni 307136 X 3,388,295 6/1968 Misencik et a1. 31711 ROBERT S. MACON, Primary Examiner US. Cl. X.R.