JPH0145294B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention does not open the primary side of a 3-winding transformer whose primary side is connected to the grid, and inputs an inspection signal from the tertiary side of the 3-winding transformer at a timely manner. , relates to an input circuit of a protective relay device that detects disconnection, short circuit, etc. of the three-winding transformer based on the output of the secondary side.

A conventional input circuit of this type of protective relay device is shown in FIG. In Figure 1, a three-winding transformer (hereinafter referred to as a transformer) 1-1
~1-3 are a primary coil 1a and a sensor 2 connected to each phase of a power transmission line (not shown) via a current transformer.
-Secondary coil 1 connected to 1 to 2-3 respectively
b, and a tertiary coil 1c connected to a common signal source via contacts 3-1 to 3-3 and supplied with the same inspection signal.

During non-inspection, contacts 3-1 to 3-3 are open, and transformers 1-1 to 1-3 are connected to primary coil 1a.
An output signal obtained from the secondary coil 1b is inputted to the sensors 2-1 to 2-3 by the input signal. The sensors 2-1 to 2-3 judge the state of the system based on input signals, and operate as a protective relay device based on the judgment result via a protection means (not shown).

During inspection, contacts 3-1 to 3-3 are closed,
An inspection signal having a predetermined constant level value is applied from a signal source (not shown) to each of the tertiary coils 1c of the transformers 1-1 to 1-3. As a result, a composite signal of the three-phase AC system input and the inspection signal is output from the secondary coil 1b, and this composite signal is output from the sensor 2-
1 to 2-3. Sensors 2-1 to 2-3
compares the input composite signal with a reference signal stored in a built-in memory, etc., and converts the transformer 1-
Detects the presence or absence of abnormalities 1 to 1-3.

The input circuit of a conventional protective relay device is configured as described above, so that during inspection, the three-phase AC input from the primary side of the transformer and the inspection signal input from the tertiary side are combined. , it is necessary to reduce the influence of the three-phase alternating current, and therefore it is necessary to increase the level of the inspection signal.

This necessarily means that the wire diameter of the tertiary coil of the transformer must be thickened and the number of turns must be increased.
This means that the overall structure of the transformer must be enlarged. Therefore, the conventional input circuit has the disadvantage that it is difficult to miniaturize it and it is difficult to obtain accurate results.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by adding the outputs obtained from the secondary coils of the transformers of each phase using an adder, the three-phase alternating current of the system can be adjusted. It is an object of the present invention to provide an input circuit for a protective relay device that cancels three-phase AC components based on characteristics and outputs only an output based on a check signal.

The circuit diagram of FIG. 2 showing one embodiment of the present invention will be described below. Transformers 1-1 to 1-3, sensors 2-1 to 2-3, and contacts 3-1 to 3-3 are the same as those shown in FIG. However, the outputs of the tertiary coils 1c of transformers 1-1 to 1-3 are supplied to an adder 4, and the output 4a of this adder 4 is supplied to a comparator 5 for comparison with a predetermined reference signal Vr. .

Next, the operation will be explained. During non-inspection, the contacts 3-1 to 3-3 are open, and the input supplied to the adder 4 is only the three-phase AC component of the system supplied via the primary coil 1a. The output 4a of the adder which adds these vectorially becomes zero due to the characteristics of three-phase alternating current.

On the other hand, during inspection, the contacts 3-1 to 3-3 are closed, and the same inspection AC signal having a constant level value is supplied to each tertiary coil 1c from a signal source (not shown). Therefore, the output of each secondary coil 1b is a combination of the three-phase AC components of the system and the inspection AC signal, and the combined output of each phase is vectorially added in the adder 4, so that the applied An output 4a that is three times the inspection AC signal (adding three phases) is obtained. The comparator 5 receives a reference signal Vr three times the value of the inspection AC signal, compares the output signal 4a from the adder 4 with the reference signal Vr, and compares the output signal 4a from the adder 4 with the reference signal Vr.
When a difference occurs between the above two signals due to a disconnection or short circuit of lines 1-3, an inspection failure signal is output.

That is, when the primary coil for one phase is disconnected, the system input for two phases and the inspection AC signal for three phases are added by the adder 4, so the output 4 of the adder 4
a is not equal to Vr. If the secondary coil for one phase is disconnected, the system input for two phases and the inspection AC signal for two phases are added by the adder 4, so the output 4a of the adder 4 is not equal to Vr. . When the tertiary coil for one phase is disconnected, the system input for three phases and the inspection AC signal for two phases are added by the adder 4, so the output 4a of the adder 4 is not equal to Vr.
Also, if each coil is short-circuited, it is the same as if it is disconnected. On the other hand, if part of each coil is short-circuited, the output of each coil decreases, so the output 4a of the adder 4 will no longer be equal to Vr. In addition, in the above explanation, the case where one phase is disconnected or short-circuited is explained, but when two phases,
Similarly, for the three phases, the output 4a of the adder 4 is
becomes no longer equal to Vr.

In the above embodiment, the adder adds analog values, but it may include an analog-to-digital conversion circuit and add digital values.

As described above, according to the present invention, inspection can be performed using an inspection signal of an appropriate level that is not affected by three-phase alternating current, so a highly accurate signal to be inspected can be obtained, and the inspection results can be relied upon. You can increase your sexuality. In addition, since it is not affected by three-phase AC, the inspection signal supplied to the tertiary side of the transformer can be small, so the diameter of the tertiary coil can be reduced and the number of windings can be reduced, making the transformer smaller. This has effects such as contributing to miniaturization of the entire input circuit.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram of a conventional input circuit, and FIG. 2 is a wiring diagram showing an embodiment of the present invention. 1-1 to 1-3...Transformer, 2-1 to 2-3...
...Sensor, 4...Adder, 5...Comparator. In addition,
In the figures, the same reference numerals indicate the same parts.

Claims (1)

[Claims] 1 A primary coil that inputs the three-phase alternating current of a system, a secondary coil connected to a sensor that detects an accident in the system, and a tertiary coil connected to an inspection signal source via a contact, and the said three-phase alternating current A transformer provided for each phase, an adder that inputs the output from the secondary coil of each phase transformer, and a failure of the transformer is detected by comparing the output of the adder with a reference signal. An input circuit for a protective relay device equipped with a comparator that outputs an inspection pass/fail signal.