Title of Invention

SWITCHING DEVICE FOR A LOAD SELECTOR

Abstract Switching device for a load selector or for a load diverter switch of a tap selector, comprising a load output line, at least two fixed tap contacts, a main switch contact directly connectable to the line by way of a respective vacuum switch, a resistance switch contact connectable to the line by way of a respective vacuum switch and a resistor, the vacuum switches being actuable independently of each other and the switch contacts being movable independently of each other and without mechanical coupling in two switching directions to switch the line from one fixed tap contact to the other and in such a movement sequence that the main switch contact reaches a new fixed tap contact before the resistance switch contact leaves the old fixed tap contact, and force storage means to initiate switching between the fix tap contacts by an abrupt release of stored force, the resistor being disposed in fixed association with the resistance switch contact so that independently of the switching direction always the same first switch contact is directly connectable to the line as main switch contact and always. the same second switch contact is connectable to the line as resistance switch contact, and the first and only the first which contact being directly actuable by said release of force.
Full Text The present invention relates to a switching device for a load selector or for a load diverter switch of a tap selector switch.
A diverter switch arrangement described in German (Federal Republic) laid-open specification 25 20 670 comprises two switch contacts, which are movable in two directions and switch the load output line over from the one to the other tap contact and of which one serves as a main switch contact and the other as a resistance switch contact, wherein both switch contacts in the stationary state lie against the same tap contact. The movable switch contacts are rigidly coupled together and arranged on a common contact carrier, and are actuated together by the movement of the common contact carrier. In dependence on the switching direction, one of the contacts always leads in alternation and the other always follows.
Each of the movable switch contacts is connected in series with a
i mechanical series contact and the two series contacts are connectible
simultaneously or individually with the load output line. This
selectable connection is effected by a movable mechanical separating
or load-diverting contact.
A force storage drive, which on release moves the two movable I switch contacts and also actuates the separating contact, is also provided in this known arrangement.
This known diverter switch arrangement has several disadvantages. On the one hand, it requires a mechanical separating contact. Vacuum switching tubes, which are advantageous because of their freedom from erosion and consequent avoidance of comtamination of the surrounding medium and also because of their high attainable switching rates, cannot be used for the known diverter switch arrangement.

On the other hand, the switch contacts in the known diverter switch arrangement change their mechanical function from leading to trailing and conversely according to switching direction; the switching sequence changes with this switching direction. Accordingly, the two switch contacts must be actuated in common by the force storage device and, in addition, the mechanical separating contact, which produces the respective connection to the load output line, must also be actuated by the force storage device, so that a complicated kinematic system and a necessarily mechanically more costly force storage device results.
The object of the invention is to provide a switching device which is usable for a load diverter switch and for a load selector, permits the use of vacuum switches in the main branch and in the resistance branch and which has simple kinematic relationships and thus needs only uncomplicated force storage means, which operates in like manner in both directions of release and provides an always identical switching step for the actuation of the fewest possible diverter switches.
According to the present invention there is provided switching device for a load selector or for a load diverter switch of a tap selector, comprising a load output line, at least two fixed tap contacts, a main switch contact directly connectible to the line by way of a respective vacuum switch, a resistance switch contact connectible to the line by way of a respective vacuum switch and a resistor, the vacuum switches being actuable independently of each other and the switch contacts being movable independently of each other and without mechanical coupling in two switching directions to switch the line from one fixed tap contact to the other and in such a movement sequence that the main

switch contact reaches a new fixed tap contact before the resistance contact leaves the old fixed tap contact, and force storage means to initiate switching between the fixed tap contacts by an abrupt release of stored force, the resistor being disposed in fixed association with the resistance switch contact so that independently of the switching direction always the same first switch contact is directly connectible to the line as main switch contact and always the same second switch contact is connectible to the line as resistance switch contact, and the first and only the first switch contact being directly actuable by said release of force.
Preferably, at least one mechanical permanent main contact, which in the stationary state bridges over the first vacuum switch, is provided in addition. Preferably, also, the resistance switch contact is movable abruptly in such a manner that the force storage means, acting in two stages, initially actuates the main switch contact and, with a time delay, the resistance switch contact. Alternatively, the resistance switch contact can be movable abruptly in such a manner that its movement takes place through a second force storage device released with a time delay.
In one preferred embodiment the main switch contact and the resistance switch contact are mounted for coaxial rotation and the fixed tap contacts extend so far in axial and vertical direction or axial and radial direction that they can be wiped by the two switch contacts independently of each other. In another embodiment, the main switch contact and the resistance switch contact are guided linearly independently of each other in such a manner that all fixed tap contacts can be wiped by the two switch contacts independently of each . other.

In yet another embodiment, the main and resistance-switch contacts each comprise two single break contacts which are actuable coupled together, wherein .. one single break contact of each of the main switch contact and the resistance switch contact is electrically connected with a first fixed tap contact and the respective other single break contact of each of the main switch contact and the resistance switch contact is electrically connected with the second fixed tap contact. In that case preferably the single break contacts of the main switch contact can be switched to by a first changeover switch and the single break contacts of the resistance switch contact can be switched to by a second changeover switch.
A particular advantage of the switching device embodying the invention is that a lowest possible switching load stress is achieved by it. Consequently, it is possible to provide, as a safety device against the unpredictable failure of a vacuum switch, a mechanical series emergency switching path, which is in any case present when the switching device is used for a load selector and which can be monitored in particularly simple manner, so as to detect response, by an opti-electronic arc detection device with circuit breaker triggering.

Furthermore, due to the low switching load stress the switching device can be constructed with smaller and correspondingly inexpensive vacuum switching tubes.
It is a particular advantage of the switching device that, due to the separate actuation of the main switch contact on the one hand and of the resistance switch contact on the other hand, a large switching path is available, which is of significance in respect of the spacing of the contact elements and thereby of the achievable voltage strength as well as in respect of the restoration voltage in the case of utilisation of the emergency switching path.
It is characteristic of the switching device that the abruptly actuated main switch contact always leads, independently of the switching direction and thereby of the movement direction of the drive.
Although it is known in principle from German (Federal Republic) patent specification No. 756 435 that, on change in direction of the contact movement of the tap selector contacts, the selector contact connected to the current-limiting resistor "overtakes" the other one, the two tap selector contacts, i.e. selector arms, in this case are coupled together mechanically and with the drive. The "overtaking" takes place either mechanically through an idle motion in the drive gear or electrically by way of two additional diverter switches which interchange the association, i.e. connection, of the tap selector contacts on reversal of direction of rotation. In a switching - device embodying the invention, thereagainst, the two contact arms are movable completely independently of the other. The main switch contact is moved suddenly to the new fixed contact by the released

force storage device and the resistance switch contact follows subsequently at a speed which is selectable as desired.
In addition, although it is known from International patent application No.W094/02955 that two selector arms of a load selector can be movable independently of each other and without mechanical coupling, the resistance contact in this case, while being driven by the drive shaft, preselects slowly and continuously with the new fixed contact during the winding up of a force storage device and the switch contact follows this movement suddenly after release of a force storage device. This arrangement is suitable only for load selectors. Moreover, a high switching load stress is present, which makes necessary additional measures beyond a mechanical emergency switching path in order to ettsure adequate reliability in spite of the uncertainties relating to failure probabilities of vacuum switches. In order to deal with such a switching stress, it is perhaps required to provide a series connection of two vacuum switches actuated at the same time in the load branch. This would increase the circuitry cost, and additional mechanical means for the simultaneous actuation of the two vacuum switches would be required.
Accordingly the present invention provides a switching device for a load selector or for a load diverter switch of a tap selector, comprising a load output line, at least two fixed tap contacts, a main switch contact directly connectable to the line by way of a respective vacuum switch, a resistance switch contact

connectable to the line by way of a respective vacuum switch and a resistor, the vacuum switches being actuable independently of each other and the switch contacts being movable independently of each other and without mechanical coupling in two switching directions to switch the line from one fixed tap contact to the other and in such a movement sequence that the main switch contact reaches a new fixed tap contact before the resistance switch contact leaves the old fixed tap contact and force storage means to initiate switching between the fix tap contacts by an abrupt release of stored force, the resistor being disposed in fixed association with the resistance switch contact so that independently of the switching direction always the same first switch contact is directly connectable to the line as main switch contact and always the same second switch contact is connectable to the line as resistance switch contact, and the first and only the first switch contact being directly actuable by said release of force.
Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which :
Fig. 1 is a schematic circuit diagram of a first diverter switch arrangement embodying the invention, as part of a load diverter switch;
Fig- 2 Is a schematic circuit diagram of this first diverter switch arrangement, but as part of a load selector;

Fig. 3 is a diagram showing the required switching steps from one voltage stage to another for the first diverter switch arrangement; Fig. 4 is a switching diagram showing repeated tap switching by
the first diverter switch arrangement; Fig, 5 is a schematic circuit diagram of a second diverter switch arrangement embodying the invention, as part of load diverter switch; Fig. 6 is a diagram showing the required switching steps from one voltage stage to another in the second diverter switch arrangement; Fig. 7 is a schematic circuit diagram of a third diverter switch arrangement embodying the invention, as part of a load diverter switch; Fig. 8 is a diagram showing the required switching steps from one voltage stage to another and back again for the third diverter switch arrangement; and Fig. 9 is a switching diagram for the third diverter switch
arrangement. Referring now to the drawings, it is to be noted that the switching sequences of the first diverter switch arrangement are in principle the same independently of whether this arrangement is used as part of a load diverter switch or as part of a load selector. The sole difference is that several switchings in the same switching direction, for example from n by way of n+1 to n+2, are possible in the case of the load selector. Although this is also the case electrically for the load diverter switch, changing is carried out mechanically only between two positions for each switching, i.e. the

switching direction is changed.
The diverter switch arrangement illustrated in Fig. 1 comprises fixed tap contacts A and B which are connected by way of a tap selector to taps n, n+1, n+2, etc., of a tapped winding.
The actual diverter switch arrangement switches between these fixed tap contacts A and B and consists of a main switch contact SKM, which is connected by way of a first vacuum switching cell or tube SKV with a common output line, and a resistance switch contact HKM, which is movable independently thereof and without mechanical coupling and which is connected by way of a series connection of a second vacuum switching cell or tube HKV and a current-limiting resistor R again with the common output line. In addition, permanent main contacts DHK/\ and DHKB, which in stationary operation carry the load current
and thereby relieve the diverter switch arrangement, are provided. The permanent main contacts are not absolutely necessary for the function of the diverter switch arrangement and the load current can, in the case of appropriate dimensioning of the vacuum switching cells, be carried by the mechanical main switch contact SKM and the first vacuum switching cell SKV, which is connected in series and remains closed in stationary operation.
Fig. 2 shows this first diverter switch arrangement as a component of a load selector. Again, the permanent main contacts are not essential. Reference has already been made to the difference in the case of actuation of the diverter switch arrangement as a component of the load diverter on the one hand and of a load selector on the other hand.
Fig. 3 shows the required switching steps from one voltage stage

to another for the first diverter switch arrangement. These switching
steps are independent of whether the switching-over takes place from a
lower to a higher voltage stage or conversely. The individual
switching steps are denoted by 1 to 11 in Fig. 3 as explained in the
following:
Switching step 1: Basic setting; contact DHK/\ carries the load
current. Switching step 2: Contact DHK/\ has opened, and the main switching
contact SKM and the first vacuum switching tube SKV have taken over the load current.
Switching step 3: The first vacuum switching tube SKV has opened,
and the load current flows by way of the resistance switch contact HKM, the second vacuum switching tube HKV and the resistor R.
Switching step 4: The main switch contact SKM after the release of a
force storage device rapidly leaves the fixed tap contact n or A.
Switching step 5: The main switch contact SKM has reached a new
fixed tap contact n+1 or B.
Switching step 6: The first vacuum switching cell SKV closes and
switches the load current to the fixed tap contact n+1 or B; merely the balancing current still flows by way of the still closed second vacuum switching cell HKV and the resistor R.
Switching step 7: The second vacuum switching cell HKV opens and
thereby interrupts the balancing current.

Switching step 8: The resistance switch contact HKM leaves the fixed
tap contact n or A and follows the main switch contact SKM in the movement to the new fixed tap contact n+1 or B.
Switching step 9: The resistance switch contact HKM has reached the
new fixed tap contact n+1 or B.
Switching step 10: The second vacuum switching cell HKV closes.
Switching step 11: The permanent main contact DHKg closes and takes
over the load current; the initial setting is reached again and the diverter switch arrangement is ready for renewed switching.
It is evident that thereby no addition of load current and balancing current takes place and only a low switching load stress is present.
Fig. 4 shows the associated switching diagram for the first diverter switch arrangement for a repeated tap switching from n to n+1, thereafter n+2 and subsequently back again to n+1 for a diverter switch arrangement according to Fig. 2. This switching diagram applies also to the arrangement, which is illustrated in Fig. 1 and in which, as explained above, mechanical changing is carried out each time only between the two fixed tap contacts A and B.
It is evident in this case that the main switch contact SKM always leads rapidly and the resistance switch contact HKM is always made to follow rapidly independently of whether a higher or a lower voltage stage is switched over to. It is accordingly necessary in that case to actuate the leading main switch contact SKM rapidly by a released spring force or other energy storage device. The trailing

resistance switch contact HKM could theoretically also be made to follow slowly or continuously, but then one of the advantages, namely the simple monitoring of the vacuum switching tubes by a mechanical emergency switching path, would not come into effect. This emergency switching can be realised only for the rapid following of the resistance switch contact HKM. This rapid movement of the trailing contact HKM is possible by means of a two-part force storage device or two force devices coupled together in such a manner that, after the release of a first storage device and movement of the main switch contact SKM, a second force storage device, which causes the resistance switch contact HKM follow, is released with a time delay.
Fig, 5 shows a second diverter switch arrangement which is structured especially for a load diverter switch and in which changing is carried out, as explained, only between the two fixed tap contacts A and B. The main switch contact SKM and the resistance switch contact HKM in this case each consist of two single break contacts SKM/\, SKMg and HKM/\, HKMg, respectively, which are actuable coupled
together, wherein first ones of the single break contacts SKM/\ and
HKMB are electrically connected with the first fixed tap contact A and the other single break contacts SKMg and HKMg are electrically
connected with the other fixed tap contact B. In this embodiment a double interruption takes place each time. Consequently, a switching-over for which only simple interrupters, contact bridges or the like are required as mechanical switching elements, is made possible in simple manner especially in the case of a load diverter switch.
Fig. 6 shows the associated switch-over operation in steps 1 to 9. It is evident that appropriate permanently present connections to

the load output line are only closed or opened each time by the respective single break contacts.
Fig. 7 shows a third embodiment of the diverter switch arrangement. This embodiment, too, is constructed for a load diverter switch, in which the switching-over again takes place only between two fixed tap contacts A and B. The single break contacts SKM/\ and SKMg, which are described further above, of the main switch contact SKM and the single break contacts HKM/\ and HKMB of the resistance switch
contact HKM are switched by two changeover switches SI and S2. The first changeover switch SI selectably closes the single break contact SKM/\ or the single break contact SKMg. In this case, a double
interruption takes place by four single break contacts, which are switchable to in particularly simple manner by only two changeover switches SI and S2.
Fig. 8 shows the associated switching-over operation from the fixed tap contact A to the fixed tap contact B and back again in steps 1 to 13. It is to be recognised that also in this embodiment the main switching contact reaches the new fixed tap contact B, i.e. connects this directly with the load output line, before the resistance-switching contact leaves the previous fixed tap contact A, i.e. interrupts its previous connection by way of the resistor R with the load output line.
It will also be recognised that the movement or actuation of the main switch contact on the one hand and the resistance-switch contact on the other hand takes place without mechanical coupling, in all described embodiments. In the case of the last-mentioned embodiments, it is also possible to provide additional permanent main contacts

which in the stationary states take over the continuous current conduction.


WE CLAIM:-
1. Switching device for a load selector or for a load diverter switch
of a tap selector, comprising a load output line, at least two fixed
tap contacts, a main switch contact directly connectible to the line
by way of a respective vacuum switch, a resistance switch contact
connectible to the line by way of a respective vacuum switch and a
resistor, the vacuum switches being actuable independently of each
other and the switch contacts being movable independently of each
other and without mechanical coupling in two switching directions to
switch the line from one fixed tap contact to the other and in such a
movement sequence that the main switch contact reaches a new fixed tap
contact before the resistance switch contact leaves the old fixed tap
contact, and force storage means to initiate switching between the
fixed tap contacts by an abrupt release of stored force, the resistor
being disposed in fixed association with the resistance switch contact
so that independently of the switching direction always the same first
switch contact is directly connectible to the line as main switch
contact and always the same second switch contact is connectible to
the line as resistance switch contact, and the first and only the
first switch contact being directly actuable by said release of force.
2. Switching device according to claim 1, comprising at least one
mechanically actuated permanent main contact which in the stationary
state of the movable switch contacts bridges over the vacuum switch
associated with the main switch contact.

3. Switching device according to claim 1 or claim 2, wherein the force storage means is provided for initially actuating the main switch contact in a first stage and then actuating the resistance switch contact in a second stage after a lapse of time following the first stage.
4. Switching device according to claim 1 or claim 2, comprising further force storage means to actuate the resistance switch contact with a lapse of time after actuation of the main switch contact.
5. Switching device according to any one of the preceding claims, wherein the said main and resistance switch contacts are optionally mounted to be rotationally movable about a common axis and the fixed tap contacts extend so far in axial and vertical direction or axial and radial direction that they can be wiped by the two switch contacts independently of each other.
6. Switching device according to any one of claims 1 to 4, wherein the said main and resistance switch contacts are optionally guided to be rectilinearly movable independently of each other so that the fixed tap contacts can be wiped by the two switch contacts independently of each other.
7. Switching device according to claim 1 or claim 2, wherein the switching device is for a load diverter switch with two fixed tap contacts and the main and resistance switch contacts each comprise two intercoupled single break contacts actuable together, wherein one single break contact of the main switch contact and one single break contact of the resistance switch contact are connected to one of the

fixed tap contacts and the other single break contacts of the main and resistance switch contacts are connected to the other one of the fixed tap contacts.
8. Switching device according to claim 7. comprising a first changeover
switch for switching to the single break contacts of the main switch contact and
a second changeover switch for switching to the single break contacts of the
resistance switch contact.
9. Switching device as claimed in claim 1 and substantially as hereinbefore
described with reference to the accompanying drawings.


Documents:

471-mas-95-abstract.pdf

471-mas-95-claims.pdf

471-mas-95-correspondence-others.pdf

471-mas-95-correspondence-po.pdf

471-mas-95-description-(complete).pdf

471-mas-95-drawings.pdf

471-mas-95-form-1.pdf

471-mas-95-form-26.pdf

471-mas-95-form-4.pdf

471-mas-95-other-document.pdf

471-mas-95-others.pdf


Patent Number 191729
Indian Patent Application Number 471/MAS/1995
PG Journal Number 30/2009
Publication Date 24-Jul-2009
Grant Date 16-Jul-2004
Date of Filing 19-Apr-1995
Name of Patentee M/S. MASCHINENFABRIK REINHAUSEN GMBH
Applicant Address FALKENSTEINSTRASSE 8, 93059 REGENSBURG
Inventors:
# Inventor's Name Inventor's Address
1 DIETER DOHNAL STEFEN-ZWEIG-STRAASE 1, 93138 LAPPERSDORF
2 HANS-HENNING LASSMANN-MIESKE HAIDAUER STRASSE 31, 93073 NEUTRAUBLING
3 LEONHARD PILLMETER HOLZGARTENSTRASSE 40, 93059 REGENSBURG
4 JOSEF NEUMEYER BUCHESTRASSE 38, 93164 WALDETZENBERG
PCT International Classification Number H01F29/04
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 P 44 41 082.4 1994-11-18 Germany
2 P 44 07 945.1 1994-03-19 Germany