JPS6040689B2 - switching switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a switching switch for a load tap switching device.

FIG. 1 shows a circuit diagram of a switching switch of a conventional load tap switching device, and FIG.
FIG. 4 is a diagram showing the opening/closing order of each current switching element (common to the embodiment shown in the figure).

A conventional load tap cutting device will be explained with reference to FIGS. 1 and 2. R in Figure 1, and R
2 indicates flow reduction resistance, respectively.

In addition, Ao and Bo are current-carrying contacts that control only energization when the on-load tap changer is stationary, A and B are main arc contacts that commutate the load current to resistance contacts, and C
, D are resistance contacts for interrupting bridging current between taps with tap switching. On the other hand, A to D, Ao in Figure 2
, Bo correspond to FIG. 1, and 1 to 1 indicate the switching process.

Now, in the conventional switching switch shown in Fig. 1, in the switching process 0' of the contact operation sequence shown in Fig. 2, the arc generated at the main arc contact A causes resistance. If contact C is connected up to the switching stage V without commutation, a short circuit will occur between the taps and the rated current of the transformer will be 1.
An overcurrent flows that reaches 0 times or even the ION sound. In such a situation, not only the switching switch but also the tap coil of the transformer will be damaged, which may be fatal to the transformer as a whole.

As a countermeasure, it is usually considered to insert a fuse Q at the position shown by the broken line in FIG. 1 to protect the taps from short circuit. However, with this configuration, if a short circuit occurs between the taps, the short circuit current will flow through both fuses Q in the same way, and both will melt, resulting in the main circuit of the transformer being disconnected, and the short circuit between the terminals of fuse Q. The line voltage of the transformer will be applied to.

Therefore, in reality, the fuse Q does not interrupt the tap-to-tap short circuit, but instead becomes an arc short circuit due to the line voltage, and has the disadvantage that it is not essential for protection. In addition, in order to eliminate such drawbacks, a configuration in which a fuse is inserted only on the side where the current is cut off is also known (for example, Taruko Publication No. 46-2133), but the configuration is complicated. It is.

The present invention has been made in consideration of the above points, and provides a sliding door switch that can protect equipment from damage due to short circuit between taps with a simple configuration in which a fuse is inserted in series with the main arc contact. The purpose is to

Embodiments of the switching switch of the present invention will be described below with reference to the drawings.

FIG. 3 is a circuit diagram showing the configuration of one embodiment. In this FIG. 3, the same parts as in FIG. I would like to state this. That is, in the embodiment shown in FIG. 3, as is clear from a comparison with FIG.
It is different from the illustration.

With this configuration, in the switching process 0' in FIG. 2, the arc of the main arc contact A reaches the switching process V
If this were to continue, as described above, a short circuit would occur between the taps and an extremely large overcurrent would flow, causing fuses 1 and 2 to melt instantly. After this fuse, 2 is blown, the voltage applied between the terminals of fuse, 2 is the vectorial sum of the tap voltage and the voltage drop across resistor R2 due to the load current of the transformer, or the voltage drop across resistor R2 due to the load current of the transformer. Fuse 1
, 2 are easily disconnected and the short circuit current is removed from the circuit.

Further, the load current of the transformer is commutated to the resistance contact D, and then, as the current-carrying contact Bo is closed, this current-carrying contact Bo
Translocated to.

At this time, the current-carrying contact B may be accompanied by a small amount of arcing, but as is known from experience, the traces of this are slight and are not severe enough to cause the current-carrying contact to suddenly lose its function. It's not a thing. Therefore, it is possible to detect the operation of the above-mentioned fuse using a known method, connect the transformer circuit breaker, replace the switching switch, and put the transformer back into operation. Become.

Also, if fuses 1 and 2 do not blow until current-carrying contact & closes, fuse 2 will be bypassed by current-carrying contact B, and after current-carrying contact B closes, only fuse 1 will blow. , open the tap-to-tap short circuit.

Furthermore, some switching switches spell out the opening/closing sequence in which the resistive contact D is involved before the energizing contact Bo is closed.

In such a case, if the fuse 2 is blown before the current-carrying contact Bo is closed, the main circuit of the transformer will be disconnected by opening the resistance contact D. However, in an actual changeover switch, the resistance contact Since the current-carrying contact Bo is already in the preparation stage for closing when D is opened, the inter-electrode distance between the movable contact and the fixed contact of the current-carrying contact Bo becomes extremely short. therefore,
Since the line voltage of the transformer is applied between these short electrodes, a preliminary discharge occurs without delay at the current-carrying contacts &, and the load current is supplied via the current-carrying contacts &. As mentioned above, in a changeover switch in which the opening/closing order in which the resistance contact D is opened before the current-carrying contact Bo is closed, the time from the opening of the resistance point ○ to the closing of the current-carrying contact Bo is Since it is usually on the order of several milliseconds, the preceding discharge due to the transformer line voltage described above poses almost no problem in practice, and does not reduce the effects of the present invention in the slightest. In the above description, the switching direction of the switching switch has been described from the energizing contact side to the energizing contact Bo side, but the same is true for the reverse case.

In addition, in order to remove the short circuit current mentioned above, we used the widely known name fuse as an element that melts in the event of an overcurrent and interrupts the circuit. It goes without saying that a similar effect can be expected if the element automatically shuts off the circuit when an overcurrent flows. Furthermore, in this invention, the fuse has another feature in that a relatively small element can be used for continuous rating because current only flows transiently during tap cutting. ``This invention has been described with reference to an embodiment using a widely known two-resistance switching switch, but the switching switch of the on-load tap switching device has a main arc contact connected in series with the selected tap, and a pre-arc contact. A contact that has another main arcing contact connected in series with the selected tap, and each of these two sets of main arcing contacts is connected in series with one or more resistors connected to one or both taps. Needless to say, any system can be easily applied as long as it follows the principle of performing tap switching by mediating the tap.

FIG. 4 is a circuit diagram showing another embodiment of the switching switch of the present invention.

This Fig. 4 shows a one-resistance type switching switch, and as is clear from comparison with the embodiment shown in Fig. 3, the resistor R2 and resistance contact D shown in Fig. 3 are omitted. The only difference from Fig. 3 is that The other parts are the same as those in the embodiment shown in FIG. 3, and the same parts are given the same reference numerals and the explanation thereof will be omitted. FIG. 5 shows each current switching element of the embodiment shown in FIG. 4, namely current carrying contacts Ao and B, and main arc contact A.
, B, shows the operating order of the resistive contact C. As described above, according to the switching switch of the present invention, a short circuit between taps does not occur due to the simple circuit configuration in which a fuse is inserted in series with the main arc contact for connection in parallel with the current-carrying contact. This can also prevent damage to the equipment.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a switching switch of a conventional on-load tap changer, and Fig. 2 is a circuit diagram showing the switching switch of the conventional on-load tap changer, and Fig. 2 is a circuit diagram showing the switching of each current switching element of the switching switch of Fig. 1 and the switching switch of the present invention shown in Fig. 3. 3 is a circuit diagram showing one embodiment of the switching switch of the present invention, FIG. 4 is a circuit diagram showing another embodiment of the switching switch of the present invention, and FIG. It is a figure which shows the opening/closing order of each electric current switching element of the sliding door switch of a figure. R,,R2... Current-limiting resistor, Mr.... Current-carrying contact, A,
B: Main arc contact, C, D: Resistance contact. Note that the same reference numerals in the figures indicate the same or equivalent parts.
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. A current-carrying contact that controls only energization when the tap switching device is at rest, connected in parallel with this current-carrying contact, and connected in series with a current-limiting impedance element, and capable of discharging bridging current between the taps during tap switching. A resistance contact for breaking the current, a main arc contact connected in parallel with the above-mentioned current-carrying contact to commutate the load current to the above-mentioned resistance contact, and a main arc contact inserted in series with this main arc contact, which does not respond to normal current but is used to handle extremely large overcurrents. A switching switch equipped with an element that automatically disconnects the circuit when current flows. 2. The switching switch according to claim 1, wherein the element uses a fuse. 3. The switching switch according to claim 1, wherein the current-limiting impedance element uses a current-limiting resistor. 4 a main arc contact connected in series with the selected tap;
having another main arcing contact connected in series with the preselect tap, and each of these two sets of main arcing contacts being connected in series with one or more resistors connected to either or both taps. 2. The switching switch according to claim 1, wherein tap switching is performed through a contact point.