JPH0132734B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a harmonic suppression type relay.

2. Description of the Related Art Relays that use a polarized relay as a detection section have been widely known as static harmonic suppression relays. FIG. 1 shows a conventional example, in which transformers 1 and 2 are provided for inputting a suppressing current and for inputting an operating current, and a polarized relay 5 is configured in the transformer 1 via a bridge rectifier 3 and a resistor 4. A suppression coil 6 is connected. The transformer 2 also includes a filter 9 consisting of a capacitor 7 and an inductance 8 for passing the fundamental current.
and a filter 12 consisting of a capacitor 10 and an inductance 11 that block fundamental wave current are connected in parallel with each other. Furthermore, the filter 9 includes a bridge rectifier 13 and a resistor 14.
The operating coil 15 of the polarized relay 5 is connected to the filter 12 through a bridge rectifier 16 and a resistor 17 to the above-mentioned suppression coil 6. Reference numeral 18 denotes an anti-vibration coil that suppresses vibrations in the operation of the polarized relay due to ripples in the input current.

In a circuit having such a configuration, when the operating current is only the fundamental wave component, most of the output current of the transformer 2 flows into the operating coil 15 through the capacitor 7 and the inductance 8, and the filter 12 consisting of the capacitor 10 and the inductance 11. Therefore, the difference between the currents flowing through the operating coil 15 and the suppressing coil 6 becomes large. As soon as the output current of the transformer 2 reaches the operating current of the polarized relay 5,
The polarized relay 5 operates and outputs the desired output signal. However, when a suppressing current is applied to the transformer 1 at this time, the suppressing current flows through the suppressing coil 6 in the opposite direction to the current flowing through the operating coil 15, so that the operation of the polarized relay 5 is suppressed. Therefore, it will not operate unless the operating current exceeds a certain ratio to the suppressing current. In this way, the function as a ratio operated relay is obtained. On the other hand, if the operating current contains many harmonic components due to excitation inrush current to the power transformer, etc., this flows through the capacitor 10 and inductance 11 to the suppression coil 6, reducing the operating sensitivity. Therefore, in a transient state where such an inrush current flows, the polarized relay 5 does not malfunction, and is a harmonic suppression type relay that is sensitive to a failure inside the transformer 2.

By the way, in a device that operates such a polarized relay 5, it will not operate unless a current higher than the sensitivity of the polarized relay 5 is passed through the operating coil 15 as an operating current, so it is difficult to operate the polarized relay 5 at high speed. For example, it is necessary to increase the secondary current of transformer 2, so from thermal considerations, transformer 1,
It is also necessary to increase the capacitance of the capacitor 7, inductance 8, and bridge rectifier 13, and there is a drawback that the entire relay cannot be made smaller. Also,
Since it is necessary to increase the suppression current to balance the operating current, other capacitors 10, inductance 11, bridge rectifier 16, and resistor 1 are used.
It is also necessary to increase the capacity of 7, etc. moreover,
In order to adjust the bypass current using the resistor 14 in accordance with the operating sensitivity of the polarized relay 5, changing the resistor 14 also changes the ratio of suppression of harmonics to the fundamental wave, so the resistor 17 must also be adjusted. It won't happen. Also, the resistor 4 must be adjusted to match the ratio characteristics. In particular, the test method for adjusting harmonic suppression characteristics is complicated and takes considerable time. Furthermore, when a full-wave rectifier circuit is used, the vibration isolation coil 18 is required because the ripples alone will cause the polarized relay 5 to vibrate, and the adjustment and structure of the polarized relay's operating value and return value are required. It becomes complicated, large in size, and expensive.

The present invention aims to improve the drawbacks of the harmonic suppressing relay using the conventional polarized relay, and in particular, the secondary coil of the transformer for operating current input is used for the operating current passing circuit and for the operating current input. A simple configuration in which the operating current and suppression current for the blocking circuit are separately connected to voltage or current level detectors, and driven by differential outputs according to the difference in each current level. Provided is a harmonic suppression type relay that operates reliably.

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

In FIG. 2, conventional polarized relay transformers 1 and 2 are used as they are, a transistor-type voltage level detector 19 is simply connected in place of the polarized relay 5, and a relay drive circuit 20 and an output relay 21 are connected to this. It is connected. In this case, resistance 1
4 and 17 are connected as shown.

In such a circuit, there is no problem when the currents passing through the bridge rectifiers 13 and 16 are in the same phase, but when they are out of phase, there is always a period in which the current flows in the a and b directions shown in the example, and in this case, the current flows in the a and b directions shown in the example. A cross current occurs, and the currents a and b do not connect points P and Q in the diagram.
There is a big change compared to the figure. There is a phase difference of approximately 90° between the currents in the circuit in which the current a flows and the circuit in which the current b flows, so the ratio between the operating current and the suppression current in Figure 1 is
What it looks like in the diagram varies greatly. This is a phenomenon caused by the coupling at points P and Q mentioned above, but in a circuit like the one shown in Figure 2, in order to take the difference between the operating voltage and the suppression voltage, the secondary side of the bridge rectifier must be This is because it is necessary to create commonalities.

Therefore, the relay shown in Fig. 3 can be considered as a relay that improves this point. According to FIG. 3, the secondary side of the transformer 2 is separated into two secondary coils 2a and 2b. According to this, the bridge rectifier 13,
Even if common connection points P and Q are made on the secondary side of 16,
A transistor-type harmonic suppressing differential relay can be easily and reliably obtained by using either a voltage level detector or a current level detector without any fear of cross current or shunt current.

Next, the operation of the circuit shown in FIG. 3 will be described.

First, when the fundamental wave operating current flows through the transformer 2, the impedance of the circuit including the capacitor 7, inductance 8, bridge rectifier 13, and resistor 14 is low, so a voltage in the operating direction is obtained between the R and S points. , the sum of this and the suppression voltage that appears between the terminals of the resistor 4 due to the suppression current is the voltage at point R,
appears as the input voltage of the voltage level detector 19 between T. When this voltage exceeds a predetermined value, a detection output is output, which activates the output relay drive circuit 20 to output an output signal. Note that the resistor 4 is variable so as to change the suppression ratio. On the other hand, if the operating current contains many harmonics or DC components, capacitor 10, inductance 11, bridge rectifier 1
6. The impedance of the circuit including the resistor 17 becomes low, and a large suppression voltage appears across the resistor 17.
Here, if the ratio of the resistors 14 and 17 is selected to be a constant value, when the components other than the fundamental wave reach a predetermined value with respect to the fundamental wave, the voltage between the R and S points becomes negative, and the input current becomes Even if it gets bigger, the relay will not operate unnecessarily.

FIG. 4 shows an example in which a transistor type current detector 22 is used. Here, the voltages obtained across the resistors 4, 14, and 17 are made into a current of a predetermined ratio by the resistors 23, 24, and 25, and the vector sum level of each current is detected by the detector 22, and the output relay drive circuit 20 The output relay 21 is activated via the .

In this way, it works in case of an internal accident in transformer 2,
A transistor-type harmonic suppression type ratio differential relay that does not operate unnecessarily in response to excitation inrush current to a transformer is obtained.

As described above, according to the present invention, by providing separate secondary coils of the operating current detection transformer for the operating current detection circuit and for the operating current blocking circuit, a transistor-type level detector can be easily applied. In addition to this, the detection level can be made much smaller than that of the polarized relay type.
It is possible to reduce the capacity and size of the input transformation circuit and other circuit elements, which is economically advantageous. In addition, the harmonic suppression characteristics are determined at the time of design by the ratio of each resistor 14 and 17, regardless of the operating level of the level detector, and are not adjusted.The suppression ratio is adjusted by resistor 4, and the operating sensitivity is determined by the level detector. It can be easily adjusted and the adjustment can be made easier. Further, according to the present invention, there are various advantages such as being able to form a harmonic suppressing relay at low cost and reliably by using a simple small level detector without using an expensive and large polarized relay. .

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional harmonic suppression type differential relay, Figure 2 is an improved circuit diagram thereof, and Figures 3 and 4 are examples of a harmonic suppression type differential relay according to the present invention. FIG. 1... Transformer for suppressing current input, 2... Transformer for operating current input, 3, 13, 16... Full wave rectifier, 9, 12... Filter, 19... Voltage level detector, 22... Current level detection vessel.

Claims (1)

[Claims] 1.Equipped with a transformer for inputting operating current and a transformer for inputting suppressing current, the secondary coil of the transformer for inputting operating current is divided into two, and one end of one coil is connected to one end of a fundamental wave passing filter. and connect one end of a fundamental wave blocking type filter to one end of the other coil, and connect the other end of each of these filters and each other end of both coils to the AC input terminal of each separate full-wave rectifier. A resistor is connected separately between the DC output terminals of these full-wave rectifiers, and the voltage difference obtained across both resistors is used as the voltage in the operating direction, and this voltage and the input of the above-mentioned suppression current are connected. The secondary coil of the transformer is connected between the AC input terminals of a full-wave rectifier, and a resistor is connected between the DC output terminals of the full-wave rectifier, and the voltage is the sum of the suppression voltage obtained across the resistor. Alternatively, a harmonic suppression type relay is characterized in that the relay drive circuit is operated when the input value is input to a current level detector and exceeds a certain value.