JPS6324578Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an operating circuit for a switch installed in a distribution line (for example, an automatic air switch for a fault section detection device), that is, an operating circuit that closes or opens the switch. The purpose of this is to supply sufficient power to the closing magnet to ensure reliable closing operation, while at the same time, after loading is completed, the power supplied to the magnet is reduced. By reducing the control voltage, the closed state can be maintained in an energy-saving state. Furthermore, by reducing the control voltage to no voltage, when opening the switch, it can be cut quickly and the contacts of the switch can be damaged. The present invention provides a switch operation circuit which can prevent accidental opening of the switch when a large current is flowing through the distribution line, and which can also simplify the configuration of the switch. It is to provide.

The drawings showing the embodiments of the present application will be described below. U, V, and W are U-phase, V-phase, and W-phase high-voltage distribution lines, respectively, where A indicates the power supply side (substation side) and B indicates the load side. 1 shows an automatic switch installed on a high-voltage distribution line. In this automatic switch 1, 2 is a switch, 3 is a magnet connected to the movable part of the switch 2, and is configured as known to close the switch 2 while it is energized and excited. has been done.
Reference numerals 5 and 6 denote first and second terminals, which are respectively connected to the magnet 3 via connection circuits as described below. Although these terminals 5 and 6 are not shown, for example, when connecting a relay and a power transformer (for example, 6900/110) to the power supply side (substation side) distribution line connected to the switch, Connected via.
Next, in the above connection circuit, 7 is a first rectifier, 7a and 7a' are DC output ends, and 7b and 7b' are AC input ends, respectively. For example, a bridge type rectifier is used as this rectifier. 8 is a step-down transformer, and 9 and 10 indicate a primary winding and a secondary winding, respectively. This step-down transformer 8 uses, for example, a power supply voltage (for example, 100V) applied to the primary winding 9.
A voltage is used in which the voltage is lowered to about a few percent (for example, 7V) and outputted from the secondary winding 10. The degree of this pressure drop is set to an appropriate value depending on the capacity of the magnet 3 or the structure of the linkage mechanism between the magnet 3 and the switch 2, and generally it is necessary and sufficient to maintain the holding state as described below. is set to a value that can be maintained. 11 indicates a second rectifier. The secondary winding 10 of the step-down transformer 8 may be connected so as to be able to supply power to the magnet 3 via a second rectifier 11 and a relay contact 12, which will be described later. Rectifier 7
or connect it to the DC output end 7a' of the
One end indicated by 1a may be connected to AC input end 7b'. 12 is a normally open relay contact. In this specification, this relay contact 12 is referred to as the first
Also called relay contact. Reference numeral 13 denotes a current limiting resistor, which limits the current caused by a back electromotive force when the magnet is opened, as will be described later. As the value, 30Ω is used as an example. 14
₁ and 14 ₂ are normally open relay contacts, respectively. Two of these contacts are connected in series so that the current to the magnet 3 can be reliably interrupted, but if one can sufficiently interrupt the current, only one may be used. Further, in this specification, this relay contact is also referred to as a second relay contact. Reference numeral 15 denotes a first relay coil, which closes the first relay contact 12 when energized.
A second relay coil 16 closes the second relay contacts 14 ₁ and 14 ₂ when energized. Reference numeral 17 indicates a switch, and as shown in the figure, a normally closed switch is used. Although this switch 17 is not shown, it is connected to the linking mechanism between the magnet 3 and the switch 2, and the switch 17
switch 17 when switch 2 is closed
It is made to open. (An example of such a mechanism is, for example, a structure in which the switch 17 is positioned close to a lever or link that is driven by the magnet 3, and the switch 17 is driven by the lever or link. 18 is a surge absorber, which is used to protect the above-mentioned connection circuit.

Next, 20 shows an overcurrent lock circuit. In this circuit, 21 and 22 are bushing type alternators, which are used when a large current that is at risk of making switching by the switch 2 impossible, that is, a large current exceeding the minimum non-interrupting current, is flowing in the high-voltage distribution line, as will be described later. The magnet 3 outputs enough power to maintain the closed state of the switch 2, as shown in FIG. 23,2
Reference numeral 4 denotes a current adjustment resistor, which is adjusted so that when the above current is the minimum non-breaking current of the switch 2, just enough power is supplied to the magnet 3 to maintain the closed state of the switch 2. The size is set. 25 and 26 indicate rectifier circuits.

Next, the operation of the above configuration will be explained.

(1) Automatic closing When an AC operating voltage (in the range of 80 to 120% of the rated operating voltage AC100V) is applied to the first and second terminals 5 and 6, the current flows as shown by the thick solid line in Figure 1. flows. As a result, all of the above AC operating voltage is rectified by the rectifier 7 and applied to the magnet 3.
A large amount of power will be supplied to the magnet 3. For this reason, the magnet 3 generates a large excitation force, and the switch 2 is reliably closed.

(2) Holding When the closing of the switch 2 is completed as described above, the switch 17 becomes open, so that current flows as shown by the thick solid line in FIG. Therefore, the magnet 3 is connected to the switch 2 while being supplied with small electric power.
The input state is maintained.

(3) Opening When the operating voltage becomes non-voltage, as a matter of course, no power is supplied to the magnet 3 and the switch 2 is opened. In this case, since the contact 12 is opened as shown in FIG. 3, the current due to the back electromotive force of the magnet 3 flows through the resistor 13 as shown by the thick solid line. For this reason, the current disappears quickly, and the magnet 3 is also quickly opened, and the switch 2 is opened in the early cut state.

(4) Overcurrent lock If a short circuit occurs in the high voltage distribution line in the above holding state and a current exceeding the minimum non-breaking current (e.g. 300A or 600A at the rated value of the switch) flows through the high voltage distribution line, a bushing type lock occurs. current transformer 21,
Either or both of 22 can produce a large output. This output is rectified by rectifiers 25 and 26 and applied to magnet 3 via resistor 13. Therefore, even if the power applied to the magnet 3 from the first and second terminals 5 and 6 is lost due to a short circuit accident as described above, the excitation state of the magnet 3 is maintained by the power from the current transformer. is maintained, the switch 2 is prevented from being opened erroneously and is maintained in the closed state.

Next, FIG. 5 is a graph showing the relationship between the resistance value of the current limiting resistor 13, the current due to the counter electromotive force, and the open time of the magnet 3. As is clear from this graph, the larger the resistance value of the resistor 13, the lower the current value and the shorter the open time. However, when the resistance value exceeds 10Ω, the above-mentioned open time does not become so short, and it becomes almost saturated at around 30Ω. Furthermore, if the resistance value is increased, a large resistor 13 with a large wattage must be used in consideration of the heat generated by the resistor 13. Further, when locking is performed as described in (4) above, if the resistance value is too large, the current necessary to hold the magnet 3 cannot be obtained.

For these reasons, the value of the resistor 13 is, for example, 30Ω. This value is for magnets,
It goes without saying that this value should be determined depending on the current transformer and other components.

As described above, in this invention, when the switch 2 is turned on, by applying the operating voltage to the first and second terminals 5 and 6, the first terminal 5 and the magnet for opening and closing the switch are connected. Since the second relay contact interposed between the first and second terminals 5 and 6 is closed as described above,
A large amount of electric power can be supplied to the magnet 3 to generate a large excitation force, which has the effect of ensuring reliable closing of the switch.

Moreover, in order to maintain the closed state of the switch after the closing of the switch is completed, a step-down transformer is installed between the first and second terminals 5 and 6 and the magnet 3 as described above. Since the magnet 8 is interposed therebetween, it has the advantage that the power supplied to the magnet 3 can be reduced. This makes it possible to reduce the electric power to the minimum electric power necessary and sufficient for the magnet 3 to maintain the closed state of the switch 2, which has the effect of greatly contributing to energy saving.

Furthermore, in the present invention, when the switch is opened by making the voltage between the first and second terminals 5 and 6 non-voltage, such as when a high-voltage distribution line is short-circuited, a The first relay contact 12 intervening in the first relay opens, and the current limiting resistor 13 intervenes in place of the contact 12.
The current due to the back electromotive force of the magnet 3 can be limited by the resistor 13 to increase the opening speed of the magnet 3, and the switch 2 can be turned off quickly. This is useful in preventing the contact points of the switch from becoming rough and allowing the switch to have a long service life.

Moreover, in the present invention, when a large current is flowing through the distribution line in the above case, power for holding the magnet is supplied to the magnet 3 from the overcurrent lock circuit 20 attached to the distribution line. This allows the switch 2 to be maintained in the closed state and prevents damage caused by accidentally opening the switch 2 while such a large current is flowing and causing damage to the switch. It has the effect of preventing

Moreover, in the present invention, when there is no voltage between the first and second terminals 5 and 6 as described above and a large current is flowing through the distribution line, the first terminal in series with the magnet 3
Even if the relay contact 12 is open, the overcurrent lock circuit 20 can supply holding power to the magnet 3, but the current limiting resistor 13 is connected in parallel to the relay contact 12 as described above. Since they are connected, the overcurrent lock circuit 20 has the advantage of being able to supply holding power to the magnet 3 as described above by simply connecting the circuit using this resistor 13. There is. This has the effect of making it easier for circuit designers to design circuits, and for those who manufacture and provide them to users, it allows them to provide them at low cost. There is.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and FIG. 1 is a circuit diagram, FIG. 2 is a diagram showing the current conduction path in the holding state, FIG. 3 is a diagram showing the current conduction path in the no-voltage open state, and FIG. FIG. 5 is a graph showing the relationship between resistance value, current, and open time. 3... Magnet, 12... First relay contact,
13...Resistor, 20...Lock circuit at the time of overcurrent.

Claims (1)

[Scope of utility model registration request] A switch installed on the high voltage distribution line is equipped with a magnet capable of closing and opening the switch, and the direct current output end of the first rectifier is connected to the magnet, and the DC output end of the first rectifier is connected to the magnet. First and second terminals are respectively connected to the AC input ends of the rectifier, and the magnet is energized or de-energized depending on whether or not power is supplied between the first and second terminals, and the opening/closing operation is performed. In the operation circuit of the switch which is configured to close or open the device, a normally open first relay contact is interposed in series with the magnet between the magnet and the DC output end of the first rectifier. , a current limiting resistor is connected in parallel to the first relay contact to limit the current caused by the back electromotive force when the magnet is opened, and the first terminal and the AC input terminal of the first rectifier are connected in parallel. A normally open second relay contact is interposed between the first and second terminals, and a first relay coil for operating the first relay contact is connected between the first and second terminals. A second relay coil for operating a second relay contact and a switch are connected in series between the terminals, and the switch opens when the magnet closes the switch. When the magnet opens the switch, the switch is linked to close the switch,
Furthermore, a primary winding of a step-down transformer is connected between the first and second terminals, and the secondary winding of the transformer is capable of supplying power to the magnet via the second rectifier and the first relay contact. and on the other hand, the high voltage distribution line is configured to output power sufficient to maintain the magnet in an energized state when a current greater than the minimum non-breaking current of the switch is flowing through the high voltage distribution line. An operating circuit for a switch, characterized in that an overcurrent lock circuit is provided, and an output terminal of the lock circuit is connected to a DC output terminal of the first rectifier.