JPS636833Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a circuit breaker or breaker that detects abnormal temperatures occurring at the terminals of the circuit breaker or breaker, indicates the abnormality, and simultaneously cuts off any fault current.

Conventionally, in this type of circuit breakers and disconnectors, if the connection was incomplete at the terminal section where the external conductor was connected, the terminal section would burn out and the molded case would burn out due to cuprous oxide multiplication heat generation phenomenon. In this case, it may cause a power short circuit.

This idea was made in view of the above points,
If an abnormal temperature rise occurs in the above terminal section, the thermistor section outputs an H level output voltage, and at the same time, the oscillator is oscillated to output H and L rectangular wave signals, and the OR gate, AND gate, The purpose of the present invention is to connect H and L voltages to the indicator light through an interface such as an abnormality display circuit, thereby causing the indicator light to blink, thereby obtaining a visually detectable circuit break or disconnection.

Hereinafter, this invention will be explained in detail based on an embodiment shown in the drawings.

Figure 1 is a circuit configuration diagram of a circuit breaker showing an embodiment of this invention, and Figure 2 is a characteristic curve diagram showing the relationship between "time and temperature rise" using the thermistor's circuit current as a parameter. FIG. 3 is a characteristic curve diagram showing the relationship between "temperature rise and output voltage" of the thermistor section.

In Figure 1, 1 is an opening/closing mechanism that opens and closes contacts using a well-known toggle link mechanism, an overcurrent trip device that trips in response to overcurrent or short circuit current, and an overcurrent trip device that occurs when the current is interrupted. Arc extinguishing devices that extinguish arcs that occur, terminals that connect electric wires and conductors,
It is a circuit breaker that consists of a probe that opens and closes a circuit and a molded case that integrates these probes.

6a to 6c are power supply side terminals having a function of connecting external conductors. 2 is quick-on and quick-off function,
This opening/closing mechanism is equipped with a trip-free function and a common tripping function that simultaneously connects and disconnects three poles, and is engaged with an electromagnetic device 9, which will be described later. 3a
3c is a heating element made of a high-resistance member inserted into each phase of the current-carrying part of the circuit and disconnector 1. 4a-4
c is a first thermistor section for detecting the temperature rise of the heating elements 3a to 3c; for example, a solid state PTC thermistor is connected to the heating elements 3a to 3;
c temperature detection element. The thermistor parts 4a to 4c exhibit high linearity with respect to temperature changes, and the resistance value changes at -65°C.
Can be used over a wide range of temperatures up to +200℃. Therefore, by configuring the thermistor section with the thermistor element, resistor, DC power supply, etc., the thermistor section can obtain the "temperature rise - output voltage" characteristic shown in FIG. For example, the temperature rise of the thermistor reaches the operating temperature TA after time t125 and t200 in Figure 2, and the output voltage becomes 1.3V, which is the threshold value.
Output. In other words, the H level output voltage is
Supplied to the input side of the OR gate. In addition, in Figure 2, if the current flowing through each phase is 100% or less, the temperature rise of the thermistor is lower than the operating temperature TA, and the temperature is TB, so the output voltage will exceed the threshold ( 1.3V), so the L level output voltage is supplied to the input side of the OR gate, which will be described later. 5 is
In the OR gate circuit, the first thermistor section 4a~
an OR gate 5A to which the output voltage of 4c is input;
It is composed of an OR gate 5B into which the output voltages of the second thermistor sections 11a to 11f are input. In the OR gate 5A, if the voltages on the input sides A, B, and C supplied from the thermistor parts 4a to 4c are all L level voltages, an L level voltage appears on the output side D, and the amplifier device described below No minute current flows through 8. However, the input sides A, B, and C supplied from the thermistor parts 4a to 4c are
If even one of the voltages is at H level, an H level voltage appears on the output side D, and a minute current is supplied to the amplifier device 8, which will be described later. Reference numeral 8 denotes an amplifier device having a function of amplifying the minute current supplied from the output side D of the OR gate 5A using a transistor circuit and a function of outputting a trigger signal from a trigger circuit. Reference numeral 9 denotes an electromagnetic device that receives the trigger signal and excites an electromagnetic coil to drive the opening/closing mechanism section 2. 7a to 7c are load side terminals having a function of connecting external conductors. 10 is an electric motor as a load. 11a to 11f are second thermistor parts that detect abnormal temperature rises of the power supply side terminals 6a to 6c and the load side terminals 7a to 7c;
For example, a solid state PTC thermistor is used as the temperature detection element of the terminals 6a to 6c and 7a to 7c. The element used is one whose resistance value changes with high linearity with respect to temperature changes, and which can be used up to a high temperature of 200°C. Examples include Mr. [trade name: TEMPSISTER].
Therefore, the above thermistor element, resistance and DC
By configuring the thermistor section using a power source or the like, an output voltage proportional to the temperature rise can be obtained. If the temperature rise of each of the terminals 6a to 6c and 7a to 7c is normal, the output voltage of the thermistor parts 11a to 11f is set to a voltage below the threshold value,
The voltage supplied to the input side of the OR gate 5B has an L level value. However, each of the above terminals 6a to 6
In c and 7a to 7c, if the terminal screws become loose, poor contact will occur, and the temperature will rise abnormally due to the copper galvanide multiplication heat generation phenomenon. At this time, the output voltage of the thermistor parts 11a to 11f is set so that a voltage higher than the threshold value is output.
The voltage supplied to the input side of the OR gate 5B is at H level. 12 is an oscillator, which is composed of an oscillation circuit integrated into an IC. The input side of the oscillator 12 is the abnormal temperature detection thermistor section 11a.
~11f output voltage. Therefore,
It does not oscillate when the input signal is at L level, but oscillates a rectangular wave signal that changes from H to L at a predetermined period only when the input signal is at H level. Note that the oscillation frequency is set to a predetermined value using a capacitor and a resistor. 15 is an AND gate whose input side is connected to the oscillator 12 and the OR gate 5B. Therefore, when the output voltage of the OR gate 5B and the output voltage of the oscillator 12 are at the L level, the output side of the AND gate 15 becomes the L level voltage. However, when the output voltage of the OR gate 5B is at H level and the output voltage from the oscillator 12 oscillates, H and L pulses are output to the output side of the AND gate 15. Reference numeral 13 denotes an abnormality display circuit, which is connected to the AND gate 15 and has a function of blinking the abnormality indicator lamp 14 when H and L pulses are input from the output side of the AND gate 15.
In addition, the OR gate 5B and the AND gate 15 are
It is provided simply to prevent malfunction of the oscillator 12, and is not particularly required functionally, so it can be omitted. In that case, the output voltage of the oscillator 12 will be directly input to the abnormality display circuit 13.

Next, the operation of the circuit and disconnector of this invention will be explained using FIGS. 1 to 3. In Figure 1, the current is from the power supply side terminals 6a to 6c to the heating elements 3a to 3c.
→ Load motor 1 through load side terminals 7a to 7c
0. When an overload current flows through this circuit, the heating elements 3a to 3c are heated by Joule heat and their temperature increases. Therefore, the thermistor part 4a
The thermistors 4c to 4c detect the temperature rise of the heating elements 3a to 3c, and exhibit the characteristics shown in FIG. 100%
Even if the current is continuously applied, the temperature rise is below the operating temperature (TA), that is, the temperature is TB. However, when 125% current is applied continuously, after t125 hours
When the operating temperature reaches TA and 200% current is continuously applied, the operating temperature reaches TA after t200 hours. Note that this relationship is generally said to be similar to the thermal characteristics of the electric motor 10. When the thermistor element reaches the operating temperature TA, the thermistor parts 4a to 4c
Since the H level output voltage, which is higher than the threshold value, is supplied to the input sides A, B, and C of the OR gate 5A, the OR
Since an H level voltage appears on the output side D of the gate 5A, the signal amplified by the amplifier 8 opens the gate of the thyristor, turning the thyristor ON. When the thyristor is turned on, the electromagnetic device 9 connected in series is activated, operating the opening/closing mechanism 2 and cutting off the fault current.

In addition, if a contact failure occurs in any one of the power supply side terminals 6a to 6c and the load side terminals 7a to 7c, the abnormal temperature detection thermistor parts 11a to 11f detect an abnormal temperature rise due to the contact failure. Then, the H level output voltage is input to the OR gate 5B. OR gate 5B is 1 on the input side.
If a high level signal is input at any time, the output side will be high.
level voltage appears. Therefore, due to the pulse oscillation of the oscillator 12 and the input of the H level signal to the OR gate 5B, the output side of the AND gate 15 has an H level.
Since the pulse voltage of and L appears, the abnormality indicator lamp 14 blinks due to the function of the abnormality display circuit 13.

Thus, by blinking the abnormality indicator light 14, it is possible to detect an abnormality in the power supply side terminals 6a to 6c and the load side terminals 7a to 7c, which are the connection portions of the circuit breakers 1 to the external conductors.

As described above, according to the present invention, in the unlikely event that the external conductor is connected to the terminals 6a to 6c and 7a to 7 of the disconnector,
If a tightening failure occurs when connecting to c,
Or, if poor contact occurs due to creep phenomenon due to aging or loosening of terminal screws, the resulting abnormal temperature rise can be detected and a strong visual warning can be issued by flashing the abnormality indicator light. . Therefore, there are effects such as being able to prevent burnout of the terminal portion and power supply short-circuit accidents. Additionally, if an abnormal current flows due to an overload, the first thermistor section detects the abnormal temperature rise in the heating element and excites the electromagnetic device via the OR gate to open the opening/closing mechanism, preventing accidents. Can cut off current.

[Brief explanation of the drawing]

Figure 1 is a circuit configuration diagram of a circuit breaker showing an embodiment of this invention, Figure 2 is a characteristic curve diagram showing the relationship between "time and temperature rise" using the thermistor's circuit current as a parameter, FIG. 3 is a characteristic curve diagram showing the relationship between "temperature rise and output voltage" of the thermistor section. In the figure, 2 is an opening/closing mechanism, 3a to 3c are heating elements, 4a to 4c are first thermistor parts, and 5A is a
OR gate, 6a to 6c are power supply side terminals, 7a to 7
c is a load side terminal, 8 is an amplifier, 9 is an electromagnetic device,
11a to 11f are second thermistor parts, 12 is an oscillator, and 13 is an abnormality display circuit.

Claims (1)

[Scope of utility model registration request] A heating element is placed in each phase of a circuit or disconnector and is heated by the current flowing through each phase, and the heating element changes resistance with high linearity in response to changes in temperature rise that occur in the heating element. The first thermistor section generates a proportional output voltage, and the resistance changes with high linearity in response to temperature rise changes occurring at the power supply side terminal and load side terminal, generating an output voltage proportional to the temperature rise. A second thermistor section is connected to the first thermistor section, and when the output voltage of any thermistor reaches a voltage higher than the threshold value on the input side, an H level voltage is generated on the output side. appears, an amplification device connected to the OR gate to amplify the minute current that flows in when the voltage of this OR gate is at H level, and a trigger signal received from the trigger circuit built into the amplification device. an electromagnetic device that operates the opening/closing mechanism section; an oscillator that is connected to the second thermistor section and outputs a square wave signal that changes to H or L only when an H level signal is applied; A circuit disconnector characterized by comprising an abnormality display circuit that blinks an abnormality indicator light in the event of an abnormality depending on the output.