JPH054850B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention is inserted into one pole of a power line,
This invention relates to a single-pole circuit breaker that disconnects the circuit when an overcurrent is detected.

(b) Prior Art Various electrical devices and wiring devices are equipped with circuit breakers and disconnectors that detect overload currents and short-circuit currents in devices and disconnect power lines. Currently, fuses, bimetal breakers, electromagnetic breakers, non-contact breakers, etc. are in practical use as circuit breakers.

Among these, non-contact breakers that use semiconductors have the advantages of being able to set the operating characteristics arbitrarily, being able to disconnect circuits extremely quickly, and making use of the characteristics of semiconductors to quickly disconnect them. It has been put into practical use as a small circuit protector. In addition, there are two types of circuit breakers and disconnectors: two-pole circuit breakers that cut both power lines, and single-pole circuit breakers that cut only one side. Single-pole circuit breakers are mainly used. Here, FIG. 4 shows a circuit diagram of a conventional single-pole circuit breaker. A predetermined voltage is always applied from the power supply section 44 to the base of the switching transistor 40 that cuts off the load current, and the switching transistor 40 is turned on. When the load current is flowing, the power supply section 44 supplies the base current. A phototransistor (light receiving side) 41b of a photocoupler 41 is connected between the base and emitter of the switching transistor 40. The LED (light emitting side) 41a of the photocoupler 41 is inserted into the load current path. Load current is resistor 46, 47
The load current on the resistor 47 side is shunted by
The current flows through the LED 41a. When the load current exceeds a certain value, the amount of light emitted from the LED 41a turns on the phototransistor 41b, and the switching transistor 4
The base and emitter of 0 are short-circuited. This cuts off the supply of base current, and the switching transistor 40 enters the cut-off state. By this,
The load current is then interrupted. Here, LED41a
The load current when the phototransistor 41b is turned on by the light emission becomes the rated current of this unipolar circuit and circuit breaker. The rated current can be determined in various ways by appropriately setting the shunt resistors 46 and 47. In the single-pole circuit breaker described above, the base current is supplied from a power supply section 44 that is separate from the power supply line.

(c) Problems to be solved by the invention However, the base current ranges from several tens of mA to several hundred mA.
Since A current flows, a large power source is required to keep the switching transistor 40 on continuously, and it is also necessary to connect to the commercial power source through a system separate from the load device. As described above, conventional single-pole circuits and circuit breakers consume large amounts of power, and the problem is that the devices become complicated and large in order to secure the power supply.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a single-pole circuit breaker that solves the above problems by deriving the operating current from the load current.

(d) Means for Solving the Problems The single-pole circuit breaker of the present invention includes a battery that supplies a forward voltage between the base and emitter of a switching transistor that interrupts the load current, and a battery that supplies a forward voltage between the base and emitter of a switching transistor that interrupts the load current. means for dividing a portion of the current into a base current of the switching transistor and supplying it as a charging current for the battery; and means for cutting off the switching transistor.

(e) Function The single-pole circuit breaker of the present invention utilizes a portion of the load current as the base current of the switching transistor and battery charging current when the load is on. When the circuit is disconnected and the load is off, the main circuit voltage changes the battery from rapid charging to floating charging. In this way, the battery is constantly charged regardless of whether the load is on or off, eliminating the need for a separate external power source.

(f) Embodiment FIG. 1 is a circuit diagram of a single-pole circuit breaker which is an embodiment of the present invention. The power supply side terminal 13 and the load side terminal 14 are connected via a diode 17 and a switching transistor 11. The switching transistor is a power transistor. The base of the switching transistor 11 is a diode 18, a resistor 15, a resistor 25, and a resistor 2.
It is connected to the power supply side terminal 13 via 7. As a result, part of the load current flows as a base current, so that the switching transistor 11 is kept in an on state. Further, a battery 12 is inserted between the power supply side terminal 13 and the load side terminal 14 via the resistor 27. When a load current is flowing, this battery 12 is trickle charged by a portion of the load current. The charging voltage to the battery is guaranteed by the sum of the voltage drops across the diode 17 and the switching transistor 11. When the load is off and no load current is flowing, the battery 12 is rapidly charged via the resistor 27 by the main circuit voltage applied between the anode of the diode 17 and the emitter of the transistor 11. Furthermore, switching transistor 1
A phototransistor 16b is connected between the base and emitter of the transistor 1. The phototransistor 16b is on the light receiving side of the photocoupler 16, and the LED 16a on the light emitting side is connected in series with a resistor 15, a thyristor 22, and a reset switch 26, and is inserted between the power supply side terminal 13 and the load side terminal 14. . In other words, the LED 16a is the thyristor 22
Lights up when the reset switch 2 is triggered.
The light goes out when 6 is pressed. A Zener diode 20 is connected to the gate of the thyristor 22 from the collector of the switching transistor 11. When the load current exceeds the rated value, the switching transistor becomes active and the Zener diode 2 is activated due to the voltage drop between the collector and emitter.
0 breaks. Break current is thyristor 2
Trigger 2. Thyristors are self-maintaining. As a result, current flows through the thyristor 22, turning on the photocoupler 16 and short-circuiting the base and emitter. This turns off the switching transistor 11. This break occurs instantaneously, and even if the load device is an electronic circuit, the power can be turned off without damage. It goes without saying that the switching transistor is cut off within the safe operating area (ASO). The load was restored and the reset switch 26 was pressed (opened).
When the thyristor 22 is cut off and the battery 1
A base current is supplied from 2 to the switching transistor via resistors 15, 25 and diode 18, and the circuit returns to its operating state.

Note that a surge absorber 19 is connected to the collector of the switching transistor 11.
A capacitor 23 and a resistor 24 are connected between the gate and cathode of the thyristor 22. The capacitor 23 is for absorbing gate noise and preventing mistrips due to thyristor noise. The resistor 24 is a gate resistor as well as a resistor for adjusting the current of the trip display LED 21.

The connection including the resistors 15, 25, and 27 corresponds to the "means for shunting a part of the load current and supplying it as the base current of the switching transistor and the charging current of the battery" of the present invention, and connects the Zener diode 20, the thyristor 22, and The photocoupler 16 corresponds to the "means for cutting off the switching transistor by cutting off the base current and battery voltage when the collector-emitter voltage drop exceeds a certain value" of the present invention.

Figure 2 shows a circuit diagram of a single-pole circuit and circuit breaker using a power transistor with a built-in sudden change thermistor. This single-pole circuit breaker uses a Zener diode 20 with a higher breakdown voltage than the single-pole circuit breaker shown in Figure 1, and the sudden change thermistor reaches the Curie temperature before the breakdown voltage is reached. In some cases, the power supply can be cut off. This allows for a certain amount of time constant from the occurrence of overcurrent until the power is cut off.
It can be used for inductive loads such as motors. In this embodiment, the same parts in the structure as the embodiment shown in FIG. A negative characteristic sudden change thermistor 30 is attached inside the switching transistor 11. This sudden change thermistor 30 is connected to the gate of the thyristor 22, and the resistor 27,
A positive potential stepped down at 15 and 25 is applied. When the switching transistor 11 generates heat above a certain temperature, the resistance value of the sudden change thermistor 30 suddenly drops and the thyristor 22 is triggered. This causes the photocoupler 16 to operate and turn off the switching transistor 11. Sudden change thermistor 30
By using a transistor with a Curie temperature that is the temperature at which the switching transistor 11 generates heat when a current exceeding the rated load current of the circuit or disconnector is passed, the time lag of temperature rise makes it suitable for inductive loads. It is possible to obtain cutting characteristics.
Further, when an extremely large overcurrent flows, the Zener diode 20 breaks and triggers the battery 12. This break is instantaneous. Thereby, the switching transistor 11 can be turned off without being damaged.

FIG. 3 is a diagram in which the single-pole circuit breaker is applied to an AC power source. Diode bridge 53-56
The unipolar circuit breaker 50 and the AC power line terminals 51 and 52 of the embodiment of the present invention were connected to the same.
As a result, all the current flows in one direction through the unipolar circuit and the circuit breaker 50, making it possible to control alternating current overcurrent.

(g) Effects of the Invention As described above, according to the single-pole circuit breaker of the present invention, a part of the load current is divided into the base current of the switching transistor and the charging current of the battery. When the circuit is disconnected, the main circuit voltage is applied to the battery, and the battery is rapidly charged and then floated charged. As a result, the battery can be constantly charged and maintain its function as a disconnector without providing a separate power supply section, and the power consumption of the device can be extremely reduced and the device can be made smaller. Furthermore, since there is no need to connect to a commercial power source, there is an advantage that installation becomes easier.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a single-pole circuit breaker which is an embodiment of the present invention, Figure 2 is a circuit diagram of a single-pole circuit breaker which is another embodiment of the invention, and Figure 3 is a circuit diagram of a single-pole circuit breaker which is an embodiment of the present invention. Figure 4 is a diagram showing the application of the single-pole circuit breaker to an AC power source, and is a circuit diagram of a conventional single-pole circuit breaker. 11...Switching transistor, 12...Battery, 16...Photocoupler, 20...Zena diode, 22...Thyristor.

Claims (1)

[Scope of Claims] 1. A battery that supplies a forward voltage between the base and emitter of a switching transistor that cuts off a load current, and a battery that divides a part of the load current to reduce the base current of the switching transistor and the battery. and means for cutting off the base current and battery voltage to cut off the switching transistor when the collector-emitter voltage drop exceeds a certain value. Single pole circuit disconnector.