JPS5836111A - Device for inspecting protective relay - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protective relay inspection device, and particularly to a protective relay inspection device that can effectively inspect a static relay.

Among protective relays, especially those called static type, the input stage of the relay is usually equipped with a transformer called an auxiliary PT and an auxiliary CT. This is because the purpose of this is to use a semiconductor circuit such as a transistor to handle the amount of electricity derived from the power system and convert the level of the amount of electricity into a fixed amount of electricity, and at the same time, the purpose is to provide electrical insulation. In addition, the static protection relay uses semiconductors in its main parts, and it is conceivable that accidental failures may lead to defects. For this reason, in many cases, a method is taken to apply a simulated operation input to the static safety relay at scheduled time intervals to confirm that the relay operates.

As for the position where the simulated operation input is applied to the relay, as is clear from the fact that the purpose is to check its function,
Input stage of relay, ie auxiliary PT.

It is most effective to apply from the auxiliary CT. For this reason, many conventional static relays have a test winding in addition to the primary and secondary windings of the auxiliary PT and auxiliary CT, and a simulated operation input for test is superimposed thereon.

Although such a device has many advantages not mentioned above, it is necessary to generate and apply a simulated operation input to each of the many relays incorporated in the device during inspection, and it is also necessary to Since the inspection input is applied to the inspection winding of the equipment, it is necessary to handle the amount of alternating current of the commercial frequency, which poses a problem of complication of the inspection equipment. Furthermore, at the time of inspection, unless special means are used, the system electricity quantity and the inspection electricity quantity will be superimposed and applied to the relay determination section, so there is a natural limit to its accuracy.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a protective relay inspection device that does not require a complicated device and can perform effective inspections.

Examples will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of an inspection device for agricultural and maintenance relays according to the present invention, FIG. 2 is an embodiment of an inspection signal superimposing circuit, and FIG. 3 is an embodiment of an inspection signal isolation circuit.

In FIG. 1, reference numeral 1 denotes an inspection signal superimposing circuit to which an inspection signal is input from the outside. Reference numeral 2 denotes a check signal superimposing circuit, which superimposes the input vl from the system and the check input from the check signal isolation circuit, and derives an output v■. Reference numeral 3 denotes an isolation amplifier, also called an isolation amplifier, which is a so-called isolator that handles analog signals. As the name suggests, this is an amplifier whose input terminal and output terminal are electrically isolated. Currently, many use high frequency transformers as isolation means. The signal applied to the input terminal is subjected to optical modulation or PWM modulation, and then applied to the above-mentioned harmonic transformer, demodulated on the secondary side of the harmonic transformer, and then appears at the output terminal. Therefore, it is possible to obtain an isolated signal identical to the input signal at the output terminal, and in principle it is also possible to transmit DC signals. Furthermore, considering that many of the products currently on the market have a free gain setting of 4, it is functionally the same as the conventional auxiliary PT, and the auxiliary P
Replacing T with an isolation amplifier does not impair its functionality. Further, the auxiliary CT can also be easily replaced with an isolation amplifier by connecting a shunt resistor to the primary side of the isolation amplifier. Reference numeral 4 denotes a relay determination circuit, which performs an error/- determination based on an inspection input. Therefore, the inspection input is superimposed on the system input, and a relay determination is made via the isolation amplifier.

The inspection and signal superimposition circuit 2 will be explained with reference to FIG.

In FIG. 2, 5.6.7.8 is a resistor, 9 is a reference voltage, IO is an analog switch, and 11 is a transistor for controlling the analog switch.

The inspection signal isolation circuit 1 will be explained with reference to FIG.

In FIG. 3, 12 is a photocoupler, 13 is a light emitting diode in the photocoupler, and 14 is a phototransistor in the photocoupler.

Next, the overall operation will be explained with reference to FIGS. 1, 2, and 783. First, consider the case where no inspection input is given.

This case corresponds to a case where the logging relay is fulfilling its original duty, and the photocoupler 12 of the inspection signal superimposition circuit (FIG. 3) 1 is inoperative. Therefore, the inspection signal superimposition circuit (
There is no entry angle of the arrow in FIG. 2), and the transistor 11 is turned on, turning the analog switch 10 off. Therefore, the reference voltage 9 is bypassed and is not superimposed on the input signal 1 of the isolation amplifier 30. Therefore, there is no hindrance to the original responsibility of the safety relay.

When an inspection input is given, that is, when the protection relay is being inspected, the photocoupler 12 of the inspection signal isolation circuit 1 is operated by the inspection input. Therefore, the check input turns off the transistor 11 and turns on the analog switch 1O, so that the electrical quantity of the reference voltage 9 is superimposed on the input signal of the isolation amplifier 3.

Here, the voltage v1 at the input terminal of the isolation amplifier 3 is determined by the voltage division ratio of the resistance value of the resistor 5 and the resistance value of the analog switch IO, since the input impedance of the isolation amplifier is generally a high resistance. Furthermore, since the on-resistance value of the analog switch 10 can generally be set to about several tens of ohms or less, the resistance value of the resistor 5 can be selected to be sufficiently higher than the on-resistance of the analog switch 10, so that vx is approximately v
r (reference voltage).

The above can be expressed numerically as follows.

(v, -vl)/R5=(v knee vr)/RON Here, R8N (if R5 is selected, it becomes ■1 in v1).

That is, since a voltage approximately equal to the reference voltage 9 appears as the output of the isolation amplifier 3 during inspection, the relay should be inspected using known means such as operating the relay circuit in the subsequent stage or changing its characteristics. is possible.

Note that it is also possible to use a voltage dividing means instead of the reference voltage 9 in the inspection signal superimposition circuit 2, and if at least one analog switch is included in the configuration, the inspection signal superimposition circuit can have various configurations. be. Further, although it is explained that a combination of a photodiode and a phototransistor is used in the photocoupler in the inspection signal isolation circuit, the combination is not limited to the above combination, and a combination of a photodiode and a photothyristor may be used. Of course.

As explained above, according to the present invention, a logic signal is input when the inspection input is applied, and each constant is determined so that the reference voltage is output to the relay based on the logic signal, so there is no need to handle the alternating current amount of the alternating frequency. It is possible to provide a protective relay inspection device that has a simple configuration and is effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of a protective relay inspection device according to the present invention, FIG. 2 is an embodiment of an inspection signal superimposing circuit, and FIG. 3 is an embodiment of an inspection signal isolation circuit. 1... Inspection signal isolation circuit, 2... Inspection signal superimposition circuit, 3... Isolation amplifier, 4... Relay judgment circuit, 5.6.7.8... Resistance, 9... Standard Voltage, 10...Analog switch, 11...Transistor, 12...Photocoupler, 13...Photodiode °, 14...Phototransistor Patent applicant Tokyo Shibaura Electric Co., Ltd. Agent Patent attorney Ishii Ki Orei 2 Figure 4 7j

Claims (1)

[Claims] In a protective relay inspection device that superimposes a check input on an electrical signal from a power grid and determines whether the relay is good or bad based on the superimposed signal, the check input is introduced and an output signal is derived via a photocoupler. a circuit, an inspection signal superimposition circuit to which an electrical signal from the system and a signal from the inspection signal isolation circuit are input, an isolation amplifier to which an output signal from the inspection signal superimposition circuit is input, and an electrical signal from the isolation amplifier. What is claimed is: 1. A protective relay inspection device comprising a relay determination circuit into which an output signal is input, and determining whether the relay is good or not based on the output of an isolation amplifier when an inspection input is applied.