JPH0580110A - Flash lamp light-emission circuit - Google Patents

Abstract

PURPOSE:To protect circuit elements by connecting a triode AC switch for divergent flow of current in parallel with a surge absorption circuit, and turning on the triode AC switch by a photo-coupler when a thyristor for actuation of light emission is turned on. CONSTITUTION:The cathode side of a light emitting diode of a photo coupler PH1 is connected with a thyristor Q3 for actuation of the photo-coupler, and the anode side is connected with a capacitor C4 in parallel connection with a capacitor C2 for light emission. When the thyristor Q3 is turned on, therefore, the electric charges on the capacitor C4 flow to the light emitting diode of the photo-coupler PH1 to turn it on. A triode AC switch Q4 for divergent flow of current is connected parallelly with a surge absorption circuit 2, and the gate of the triode AC switch is coupled with the photo-coupler PH1, so that the triode AC switch Q4 is turned on when the photo-coupler PH1 is turned on, and most of the current flowing to the surge absorption circuit 2 flows divergently to the triode AC switch 4, and a Zenor diode ZD1 is protected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash lamp light-emitting circuit for a flash-on indicator which operates by detecting a ground-fault current flowing when an accident occurs on a transmission / distribution line.

[0002]

2. Description of the Related Art A flashover indicator is used by being attached to a steel tower of a transmission and distribution line in order to make it easy to find a steel tower where a flashover accident has occurred. Conventionally, explosive-type and mechanical-type indicators have been known. Has been. However, as a flash-on indicator that is easier to maintain and more reliable than conventional ones, the applicant has made a flash lamp emit light when a ground-fault current flows, and utilizes the destruction of the flash lamp due to light-emission. We have developed a method of displaying a contact and have already applied for a patent.

The flash lamp light-emitting circuit incorporated in the flash-on indicator of this prior application has a rectifier circuit in a current transformer (CT) for detecting a ground-fault current via a surge absorbing circuit composed of a zener diode and a capacitor. The light-emitting capacitor, the light-emitting operation thyristor, and the flash lamp are connected to this rectifying circuit. This circuit charges the light emitting capacitor by the ground fault current detected by the current transformer, and when the terminal voltage of the capacitor reaches a predetermined value, it turns on the light emitting operation thyristor and charges the light emitting capacitor. It is a method of flowing it through a flash lamp.

However, the flash lamp light emitting circuit of this flashover indicator was developed for the conventional 77KV transmission line, and when it is attempted to expand the range of application to the higher voltage 154KV transmission line, the short-circuit current value is increased. Since it is larger than the 77KV transmission line, when a short-circuit accident occurs, a large CT secondary current flows and heat generation destroys circuit elements such as Zener diodes. For this 77
It is possible to change the Zener diode of the flash lamp light emitting circuit for the KV transmission line to a large-capacity one, but the cost of the Zener diode becomes high and the size of the Zener diode becomes large. Further, it may be possible to manufacture a flash lamp light emitting circuit dedicated to 154 KV, but this is not preferable because it causes a problem of increased manufacturing cost.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a flash lamp light emitting circuit which can be applied to a 154KV transmission line having a large short circuit current value by utilizing the conventional circuit as it is. It was completed in.

[0006]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, provides a current transformer (C) for detecting a ground fault current.
T) is connected with a rectifier circuit, a light emitting capacitor, a light emitting operation thyristor, and a flash lamp via a surge absorption circuit, and operates when the light emitting operation thyristor conducts to the cathode side of the light emitting operation thyristor. The flash lamp light-emitting circuit is characterized in that a photo-coupler is connected to the photo-coupler and the current shunt triac connected in parallel to the surge absorbing circuit is operated by the photo-coupler.

As described above, according to the present invention, the current shunt triac is connected in parallel with the conventional surge absorbing circuit, and when the light emitting operation thyristor is turned on, the current shunt triac is turned on by the photocoupler and detected by the CT. Also, most of the short-circuit current is shunted to this triac to protect the circuit elements such as the Zener diode of the surge absorbing circuit. The invention will now be described in more detail by means of the illustrated embodiment.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 is a conductor through which a ground fault current flows when a flashover accident occurs, and a CT attached to this conductor 1 detects the ground fault current. The rectifier circuit 3 is connected to the secondary side of the CT via the surge absorbing circuit 2.
Although the surge absorbing circuit 2 is composed of the bidirectional Zener diode ZD1 and the bypass capacitor C1, it is possible to use a varistor or an arrester instead of the bidirectional Zener diode ZD1. The rectifier circuit 3 is composed of a bridge diode D1 and is a circuit for rectifying an AC ground fault current. R1 is a resistor for adjusting the charging speed of the light emitting capacitor C2 connected to the DC side of the rectifier circuit 3.

A flash lamp 4, a light emitting capacitor C2 for storing electric charges for causing the flash lamp 4 to emit light, and a light emitting operation thyristor Q2 are connected to the DC side of the rectifier circuit 3. A resistor R2 is connected in parallel with the light emitting capacitor C2. The resistor R2 is for ensuring the charging voltage of the light emitting capacitor C2 and for providing a discharge resistance.

A capacitor C3, which is charged at a slower speed than this, is connected in parallel with the light emitting capacitor C2. The charging speed of the capacitor C3 is determined by the resistor R3. The terminal voltage P2 of the capacitor C3 is divided by the voltage dividing resistors R5 and R6 and applied to the reference of the shunt regulator Q1. The shunt regulator Q1 is a switching element having a built-in temperature compensation circuit, and has a function of electrically connecting the cathode and the anode when the reference voltage reaches a predetermined value.
Further, since it has a temperature compensation circuit, it operates stably even in a low temperature region of -20 ° C or lower.

A resistor R7 for supplying a current to the shunt regulator Q1 and a transistor TR1 are connected to the cathode of the shunt regulator Q1. The transistor TR1 is of PNP type, its base is connected to the cathode of the shunt regulator Q1, and its collector is connected to the gate of the thyristor Q2 for light emission operation. R9 is a resistor for generating a terminal voltage of the gate.

The above-mentioned configuration is the same as the circuit of the prior application, and in order to make the description easy to understand, the operation of the circuit having the above-described configuration will be described first. First, when a ground fault current flows through the conductor 1 due to a flashover accident, the CT detects this and produces an AC output on its secondary side. This output passes through the surge absorbing circuit 2 to absorb the surge, and a voltage having a waveform as P0 in FIG. 2 is generated on the AC side of the rectifying circuit 3.

This voltage is rectified by the rectifier circuit 3 and charges the light emitting capacitor C2 connected to the DC side of the rectifier circuit 3, so that the potential of P1 rises for each wave as shown in FIG. The electric charge for causing the light to be emitted is stored. At the same time, the capacitor C3 connected in parallel with the light emitting capacitor C2 is also charged. However, since the capacitor C3 is charged via the resistor R3, its charging speed becomes slower than that of the light emitting capacitor C2. The terminal voltage rises as shown by P2 in FIG.

The terminal voltage P2 of the capacitor C3 is divided by the voltage dividing resistors R5 and R6 and rises as indicated by P3 in FIG. This voltage P3 is applied to the gate of the shunt regulator Q1, and when the value reaches a predetermined level (2.5V in the embodiment), the shunt regulator Q1 becomes conductive and a current flows from the emitter of the transistor TR1 to the base. Along with this, the transistor TR
A current also flows through the resistor R9 connected to the collector of 1, and P
The potential of 4 changes as shown in FIG. 2 and is applied to the gate of the light emitting operation thyristor Q2.

At the same time, the light emitting operation thyristor Q2 becomes conductive, and the electric charge stored in the light emitting capacitor C2 until then is instantaneously supplied to the flash lamp 4 as P5 as shown in FIG. As a result, the flash lamp 4
Will be emitted and destroyed, and the flashing indicator will be activated reliably.

In the present invention, the following protection circuit is added to the above-mentioned flash lamp light emitting circuit of the prior application as a shunt circuit that operates after the flash lamp emits light. First, a differentiating circuit 5 including a capacitor C5 and a resistor R8 is connected to the cathode side of the light emitting operation thyristor Q2, and when the light emitting operation thyristor Q2 becomes conductive, a gate voltage shown as P6 in FIG. 2 is generated. Q3 is a photocoupler operating thyristor, and since the gate of the thyristor is connected to the differentiating circuit 5, when the light emitting operating thyristor Q2 becomes conductive, the photocoupler operating thyristor Q3 becomes conductive.

PH1 is a photocoupler, the cathode side of the light emitting diode is connected to the photocoupler operating thyristor Q3, and the anode side is a light emitting capacitor C.
It is connected to a capacitor C4 which is connected in parallel with the capacitor 2. For this reason, when the photocoupler operating thyristor Q3 becomes conductive, the charge stored in the capacitor C4 flows to the light emitting diode of the photocoupler PH1 and causes the light emitting diode to emit light to make the photocoupler PH1 conductive. Note that D2 is a diode that prevents the charge stored in the capacitor C4 from flowing when the flash lamp emits light, and R10 is a capacitor C4.
R11 is a resistor for adjusting the discharge time and protecting the light emitting diode, and R11 is a resistor for protecting the light emitting diode.

On the other hand, a current shunt triac Q4 is connected in parallel to the surge absorbing circuit 2. Since the gate is connected to the photocoupler PH1, the current shunt triac Q4 is turned on when the photocoupler PH1 is turned on, and most of the current flowing in the surge absorption circuit 2 is transferred to the current shunt triac Q4. Divert. As a result, the flash lamp light emitting circuit of the present invention
Even when used in a 154 KV transmission line, it is possible to prevent the circuit elements such as the Zener diode ZD1 from being destroyed by heat generation. R12 is a photo coupler PH
It is a resistor for adjusting the current flowing through 1 and for generating the gate signal of the current shunt triac Q4.

A coil L1 is connected in series to the current shunt triac Q4. This is to prevent all current from suddenly flowing into this circuit when the current shunting triac Q4 is turned on, and to flow a part of the current to the rectifier circuit 3 side to constantly supply electric charge to the capacitor C4. .. That is, in the circuit of the present invention, it is necessary to always apply a voltage to the gate of the current shunting triac Q4 to make it conductive while an overcurrent flows through the circuit. When the current is shunted to the capacitor C4, the capacitor C4 is not charged thereafter, and the voltage supply to the gate of the current shunt triac Q4 is stopped. For this purpose, a coil L1 is provided and a capacitor C4
The current can be made to flow to the side as well.

[0020]

As described above, in the flash lamp light emitting circuit of the present invention, when a photo coupler or a current shunting triac is connected to the circuit for 77KV of the previous application, an excessive overcurrent flows in the circuit. Also, by dividing this, the circuit elements such as the Zener diode ZD1 can be protected. Therefore, the present invention makes a great contribution to the industry as a low-cost flash lamp light-emitting circuit that can be applied to a 154 KV transmission line with a large short-circuit current value while using the circuit of the prior application as it is.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a voltage waveform diagram generated at points P0 to P8 at the time of a flashover.

[Explanation of symbols]

 1 conductor 2 surge absorption circuit 3 rectifier circuit 4 flash lamp CT current transformer C2 light emitting capacitor Q2 light emitting operation thyristor PH1 photocoupler Q4 current shunt triac

Claims (1)

[Claims] 1. A ground fault current detecting current transformer (CT) is connected to a rectifying circuit, a light emitting capacitor, a light emitting operation thyristor, and a flash lamp via a surge absorbing circuit, and a light emitting operation is performed. A photocoupler that operates when the light-emitting operation thyristor conducts is connected to the cathode side of the thyristor for use, and the current shunt triac connected in parallel to the surge absorption circuit is operated by this photocoupler. Flash lamp light emitting circuit.