JP2652737B2 - Short circuit tester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short-circuit tester, and more particularly to a circuit tester for testing DC equipment provided in a power station or a substation by artificially shorting a circuit. Such a short-circuit tester.

[0002]

2. Description of the Related Art FIG. 1 is a diagram showing an outline of a power transmission path from a power plant to a substation and a control station for monitoring the substation. FIG.
In, power generated by the power plant 1 is supplied to each substation 4 via a power line 3 stretched over a steel tower 2, is reduced in voltage to a predetermined voltage, and is supplied to each customer. Each of the substations 4 is unmanned, and is remotely monitored and controlled by the control station 5.

[0003] The substation 4 is provided with a relay panel 6, and the control station 5 is provided with a monitoring panel 7 and a control console 8.
The relay panel 6 displays on the monitor panel 7 the current state of each device such as whether the oil level of the transformer body in each substation has dropped or whether the operating air pressure of the circuit breaker has dropped. The watch has a built-in relay.
Knowing that the oil level of the transformer body has dropped,
Take the necessary measures, for example.

FIG. 2 is a diagram showing a part of the wiring in the relay panel shown in FIG. 1. FIG. 3 is a diagram for testing the operation state of the equipment by short-circuiting a terminal plate provided on the back of the relay panel. FIG. 4 is a diagram for explaining a method of performing the operation.

The relay panel 6 uses 100 V DC and 200 V AC supplied from a battery 61 as a power supply. 100 V DC is supplied from the switch contacts 62 and 63 to the auxiliary relay 65 via the relay contact 64. Further, DC 100V is applied to the D through switch contacts 67 and 68.
The DC / DC converter 69 is connected to the C / DC converter 69 and supplies 24 V DC to another device (not shown).

When a DC current flows through the auxiliary relay 65, the alarm contact 66 is closed, and an alarm indicator (not shown) of the monitoring panel 7 is turned on. In order to test whether the alarm indicator lights normally, the relay contact 64 may be short-circuited. A terminal plate 70 as shown in FIG.
The points P and A2 shown in FIG.
Connected to 0. Therefore, if the point P and the point A2 of the terminal board 70 are short-circuited, the operation state of the alarm display can be tested.

[0007]

In order to perform the above-mentioned short-circuit test, as shown in FIG. 3 (b), the terminal plate 70 is short-circuited by using a lead wire 72 with a clip to which a glass tube fuse 71 is connected. A method is used. However, the X and Y points of the AC 200 V system are wired adjacent to the A2 point on the terminal board 70, and the A2 point and the P point should be short-circuited to the A2 point by mistake. , P point and X point may be brought into contact. In that case, DC 100V and AC 200V are in contact with each other, and the auxiliary relay 65 is damaged, or an erroneous signal is output from the relay panel 6 to cut off the circuit breaker and cut off the power transmission to the transmission line, There is a possibility that the DC / DC converter 69 may be damaged and the control console 8 may become uncontrollable.

For this reason, a method has been proposed in which the terminals other than the terminals to be tested are cured with an insulating tape, and the terminals to be tested are tested with a voltage checker to check that no contact occurs. In each case, only measures that depended on human judgment and behavior were taken, and no physical measures were taken.

Therefore, a main object of the present invention is to automatically detect a contact between DC and AC and a short circuit current, and in such a case, to make the device non-conductive and cause a human error or power supply even if a human error occurs. An object of the present invention is to provide a short-circuit tester that operates actively so as not to cause a defect such as a short-circuit.

[0010]

The invention according to claim 1 is
In a short-circuit tester for short-circuiting a DC device and testing the operation of the DC device, a pair of input terminals, a rectifying circuit for rectifying a voltage input to the pair of input terminals and outputting the rectified voltage to positive and negative terminals, A voltage dividing circuit connected between the positive and negative terminals of the rectifying circuit for dividing the rectified DC voltage, and conducting when the divided voltage exceeds a predetermined value, and connecting between the positive and negative terminals of the rectifying circuit; , A time constant circuit connected between the positive and negative terminals of the rectifier circuit, and a voltage output from the time constant circuit when the first switching circuit is non-conductive. A second switching circuit that conducts in response to exceeding a predetermined value and short-circuits between the positive and negative terminals of the rectifier circuit.

[0011]

[0012]

The short-circuit tester according to the present invention rectifies a voltage input to a pair of input terminals, divides the rectified voltage by a voltage dividing circuit, and the divided voltage exceeds a predetermined value. The time constant connected between the positive and negative terminals of the rectifier circuit when the first switching circuit is conductive and the positive and negative terminals of the rectifier circuit are short-circuited and the first switching circuit is nonconductive. When the voltage output from the circuit exceeds a predetermined value, the second switching circuit is turned on, and the positive and negative terminals of the rectifier circuit are short-circuited. Even if the contact between the terminal and the terminal of the DC voltage straddles, there is no possibility that the DC and the AC may contact each other.

[0013]

FIG. 4 is an electric circuit diagram of one embodiment of the present invention. Referring to FIG. 4, the short-circuit tester has a pair of input terminals A,
B, an input circuit 11, a determination circuit 12, and a main conduction circuit 13. When the instantaneous value of the voltage input from the pair of input terminals A and B to the input circuit exceeds 140 V, the determination circuit 12 determines that the instantaneous value has exceeded 140 V, and prevents conduction of the main conduction circuit 13, and the pair of input terminals When the voltage input from A and B to the input circuit 11 is 1
When the determination circuit 12 determines that the DC voltage does not exceed 40 V, the main conduction circuit 13 is turned on to short-circuit the pair of input terminals A and B. That is, the input terminals A,
When the instantaneous value of the voltage input between B and B is a voltage exceeding 140 V, a short circuit between the pair of input terminals A and B is prevented, and when the input voltage is a DC voltage not exceeding 140 V. Only to prevent short circuit between the pair of input terminals A and B.

More specifically, a pair of input terminals A and B are terminals for short-circuiting the terminal plate 70 shown in FIG. 3, and a voltage inputted to the input terminals A and B is a DC voltage,
Irrespective of the AC voltage, the signal is input to the full-wave rectifier D1 via the fuse F of the input circuit 11, the polarity is rectified, output between the nodes P and N, and input to the determination circuit 12. The determination circuit 12 includes resistors R1 and R2 connected between nodes P and N.
And a series circuit of the resistor R3 and the thyristor SR1. When the instantaneous value of the voltage between nodes P and N exceeds 140 V, resistors R1 and R2 apply a gate voltage for conducting thyristor SR1 to the gate of thyristor SR1. Accordingly, thyristor SR1 conducts. That is, the instantaneous value of the thyristor SR1 is 1 regardless of whether the voltage input between the pair of input terminals A and B is an AC voltage or a DC voltage.
When it exceeds 40V, it conducts.

The main conducting circuit 13 includes a resistor R3, resistors R4 and R5 connected in series between the anode of the thyristor SR1 and the node N, a capacitor C connected in parallel to the resistor R5, and a node P and N. It includes a connected thyristor SR2. The resistors R4 and R5 and the capacitor C constitute a time constant circuit, and the voltage generated by the time constant circuit is applied to the gate of the thyristor SR2 as a gate voltage. When the input voltage is, for example, DC 80 V, the final voltage charged in the capacitor C reaches, for example, 0.6 V or more, and the resistances R4,
The values of R5 and capacitor C are selected.

FIG. 5 shows the operation of the thyristors SR1 and SR2 when DC 100 V is applied between the input terminals A and B.
6 shows the operation of the thyristors SR1 and SR2 when AC 100 V is applied between the input terminals A and B. FIG. 7 shows the operation when AC 100 V and DC 100 V are applied between the input terminals A and B in a mixed manner. FIG. 4 is a diagram showing the operation of thyristors SR1 and SR2.

Next, the operation of one embodiment of the present invention will be described with reference to FIGS. As shown in FIG.
When 100 VDC is applied between the input terminals A and B, the resistance R1
And R2 are applied to the gate of thyristor SR1. However, when the voltage between the nodes P and N exceeds 140V, the resistors R1 and R2 become thyristor SR.
The thyristor SR1 does not conduct because the resistance value is selected so as to generate a gate voltage that makes the 1 conduct. On the other hand, the capacitor C of the main conduction circuit 13 is gradually charged through the resistors R3 and R4,
When the gate voltage reaches 0.6 V after a lapse of 0 msec, the thyristor SR2 conducts, and the input terminals A and B are short-circuited.

Next, as shown in FIG. 6, input terminals A and B
When AC 100V is applied during that time, the instantaneous value becomes 140
Since V exceeds V, the thyristor SR1 conducts. Resistance R
Since R4 and R5 are short-circuited, the charging voltage of the capacitor C does not increase to the gate voltage required to make the thyristor SR2 conductive, and the thyristor SR2 remains off. Therefore, the input terminals A and B are not short-circuited.

Next, as shown in FIG.
If AC 100V and DC 100V are input in a mixed state during that time, the instantaneous value greatly exceeds 140V.
The thyristor SR1 conducts. Since the resistors R4 and R5 are short-circuited, the charging voltage of the capacitor C does not increase, and the thyristor SR2 remains off. Therefore, if AC 100 V and DC 100 V are input between the input terminals A and B in a mixed state, the input terminals A and B are not short-circuited.

FIG. 8 is an electric circuit diagram showing a more specific embodiment of the present invention. In the example shown in FIG. 8, a security circuit 14 is newly provided in the example shown in FIG.
A green light emitting diode LED1 for displaying when a voltage is input between the input terminals A and B, and a red light emitting diode LED2 for displaying a short circuit when a DC voltage is input between the input terminals A and B. And a buzzer BZ for notifying it. When the input terminal A and the input terminal B become conductive and the DC current becomes excessive, the thyristor SR3 becomes conductive, and the security circuit 14 turns on the SR.
4 is made non-conductive, and the resistors R8 and R11 protect the circuit by allowing only a few tens of mA to flow through the main conductive circuit 13. The green light emitting diode LED1 is connected to the node P
And the resistor R3, and the red light emitting diode LE
D2, resistor R10 and buzzer BZ are connected to node P and security circuit 1.
4 is connected. Note that a parallel circuit of a capacitor C2 and a resistor R7 is connected between the resistor R1 and the cathode of the green light emitting diode LED1. Capacitor C
2 makes the thyristor SR1 more sensitive to the AC voltage input than the embodiment shown in FIG. It is provided to eliminate everything.

[0021]

As described above, according to the present invention, it is determined whether or not the voltage input between the pair of input terminals is direct current, and in response to the determination that the voltage is direct current, When a pair of input terminals is short-circuited, and when an AC voltage or a DC voltage and an AC voltage are input in a contact state, the pair of input terminals are made non-conductive, so there is no human error. However, it does not lead to malfunctions such as equipment failure or power supply short circuit.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a power transmission path from a power station to a substation and a control station that monitors the substation.

FIG. 2 is a diagram showing a part of wiring in a relay panel.

FIG. 3 is a diagram for explaining a method of testing an operation state of a device by short-circuiting a terminal plate provided on a rear surface of a relay panel.

FIG. 4 is an electric circuit diagram of one embodiment of the present invention.

FIG. 5 is a diagram for explaining the operation of the thyristor when a direct current of 100 V is applied between input terminals A and B.

FIG. 6 is a diagram for explaining the operation of the thyristor when AC 100 V is applied between input terminals A and B.

FIG. 7: AC 100 V and DC 100 between input terminals A and B
It is a figure for explaining operation of a thyristor at the time of giving V by making V touch.

FIG. 8 is an electric circuit diagram showing a more specific embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Input circuit 12 Discrimination circuit 13 Main conduction circuit 14 Security circuit D1 Full-wave rectifier SR1-SR4 Thyristor R1-R13 Resistance LED1, LED2 Light emitting diode C, C1-C5 Capacitor

Claims (1)

(57) [Claims] 1. A short-circuit tester for short-circuiting a DC device and testing the operation of the DC device, comprising: a pair of input terminals; a voltage input to the pair of input terminals is rectified and output to positive and negative terminals. A rectifier circuit, which is connected between the positive and negative terminals of the rectifier circuit and divides the rectified DC voltage, in response to the voltage divided by the voltage divider circuit exceeding a predetermined value. A first switching circuit that conducts and short-circuits between the positive and negative terminals of the rectifier circuit, a time constant circuit that is connected between the positive and negative terminals of the rectifier circuit, and when the first switching circuit is non-conductive. A short-circuit tester comprising: a second switching circuit that conducts in response to a voltage output from the time constant circuit exceeding a predetermined value and short-circuits between the positive and negative terminals of the rectifier circuit.