JPS636834Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to circuits and disconnectors.
For example, customers have requests for circuits and disconnectors that issue a warning before operation when there is a low overload because there are circuits that would be problematic if the electrical circuits were automatically disconnected.

Therefore, this device immediately issues an alarm with a buzzer when an overload current flows into a circuit or disconnector, and waits for a period of time specified by JIS standards (for example, 60 minutes for an overload current of 125%). For safety reasons, the electric circuit is automatically cut off when the current reaches 200% overload (within a few minutes).

Fig. 1 is a circuit configuration diagram of a circuit breaker showing an embodiment of this invention, and Fig. 2 shows a "temperature rise over time" using the circuit current flowing into the heating element as a parameter.
FIG. 3 is a characteristic curve diagram showing the relationship between "temperature rise and output voltage" of the overload detection temperature sensor.

In Figure 1, 1 is a switching mechanism that opens and closes contacts using a well-known toggle link mechanism, an overcurrent tripping device that trips in response to overcurrent or short-circuit current, and It is a circuit breaker that is composed of an arc extinguisher that extinguishes the generated arc, a terminal that connects electric wires and conductors, a contact that opens and closes the circuit, and a molded case in which these are integrated.

6a to 6c are power supply side terminals having a function of connecting external conductors. 2 is quick entry and quick cutting 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 consisting of a high resistance part inserted into each phase of the normal part of the circuit and disconnector 1. 4a-4c
is a temperature sensor for overload detection, for example, a solid state PTC thermistor is connected to the heating element 3a~
3c temperature detection element. This element exhibits high linearity with respect to temperature changes, and its resistance value changes, and can be used over a wide range of temperatures from -65°C to +200°C. Therefore, by configuring the sensor with the thermistor element, resistor, DC power supply, etc., the temperature sensor for overload detection can obtain the "temperature rise - output voltage" characteristic shown in FIG. For example, in Fig. 2, the temperature rise of heating elements 3a to 3c becomes the operating temperature after time t125 and t200.
It becomes TA and outputs the threshold output voltage of 1.3V. In other words, an H level output voltage is supplied to the input side of an OR gate, which will be described later. In addition, in Fig. 2, if the current flowing through each phase is 100% or less, the temperature rise of the heating elements 3a to 3c is lower than the operating temperature TA, and the temperature is TB, so the output voltage will be lower. Since it is lower than the threshold (1.3V), the L level output voltage is supplied to the input side of the OR gate described later. 5 is the first OR gate, and if the voltages on the input sides A, B, and C supplied from the overload detection temperature sensors 4a to 4c are all L level voltages, the output side D has an L level voltage. appears, and no minute current flows through the amplifier device 8, which will be described later. However, if even one of the voltages on the input sides A, B, and C supplied from the overload detection temperature sensors 4a to 4c is at H level, an H level voltage will appear on the output side D. , a minute current is supplied to an amplifier device 8, which will be described later.
Reference numeral 8 denotes an amplifying device having a function of amplifying the minute current supplied from the output side D of the OR gate 5 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. 1
0 is an electric motor as a load. 11a-11c
is an overload current detection sensor, which is composed of a CT and a resistor in order to immediately generate an output voltage on the secondary side when an overload current flows, for example. Therefore, the overload current detection sensor 11a~
When no overload current flows, the output voltage of 11c is at a voltage below the threshold value, that is, an L level state, and when an overload current flows, it becomes a voltage above the threshold value, that is, an H level state. is set to .

12 is an overload current detection sensor 11a to 11
A second OR gate to which the output voltage of c is applied to the input side, and the overload current detection sensors 11a to 11
If all the voltages on the input side supplied from c are at L level, an L level voltage will appear on the output side, but if there is even one H level voltage among the input side voltages, an H level voltage will appear on the output side. level voltage is beginning to appear. 13 is an alarm device connected to the output side of the second OR gate 12, such as a piezoelectric buzzer;
It consists of a voltage-driven buzzer that generates an electronic sound, and is set to generate an electronic sound only when an H level voltage is supplied from the OR gate 12.

Next, the operation of this invention will be explained using FIGS. 1 to 3. In Figure 1, the current is at the power supply side terminal 6a.
~6c → Heating elements 3a~3c → Load side terminals 7a~7
It is supplied to the load motor 10 through c. When an overload current flows through this circuit, the heating elements 3a to 3c
is heated by Joule heat and its temperature rises. Therefore, the thermistors of the overload detection temperature sensors 4a to 4c detect the temperature rise of the heating elements 3a to 3c, and exhibit the characteristics shown in FIG. 2. Note that for 100% current, even if the current is applied continuously, the temperature rise will be the same as the operating temperature.
The temperature is below TA, that is, TB. but,
When 125% current is applied continuously, TA after t125 hours
When the operating temperature reaches TA, and when 200% current is continuously applied, the operating temperature reaches TA after t200 hours. In addition,
This relationship is generally said to be similar to the thermal characteristics of the load motor 10. When the thermistor element reaches the operating temperature TA, the overload detection temperature sensors 4a to 4c supply a threshold H level output voltage to the input sides A, B, and C of the OR gate 5.
Since an H level voltage appears on the output side D of the OR gate 5, the signal amplified by the amplifier 8 opens the gate of the thyristor, and the thyristor turns on.
do. 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. Further, when an overload current flows through the overload current detection sensors 11a to 11c, the output voltage of the OR gate 12 immediately becomes H level, and the piezoelectric buzzer 13 is driven to generate an alarm with an electronic sound.

As described above, according to this invention, when an overload current flows, an overload detection temperature sensor detects a temperature rise of the heating elements 3a to 3c having thermal characteristics similar to those of the electric motor 10 of the load. 4a-4c
When it reaches the operating temperature, it outputs an output voltage, obtains an interface, and operates the opening/closing mechanism section 2 by the electromagnetic device 9.
In other words, after the overload current flows into the circuit or disconnector, the circuit is automatically disconnected after a period of time specified by JIS standards has elapsed. On the other hand, when an overload current flows into the circuit or the disconnector, the overload current detection sensors 11a to 11c quickly detect the overload current, and the OR gate 1
2, the piezoelectric buzzer 13 generates an alarm when an H level voltage appears on its output side. In other words, according to the present invention, when an overload current flows into a circuit or breaker, an alarm can be issued before the circuit or breaker operates, so some kind of alarm can be issued before the circuit or breaker is disconnected. It has the effect of being able to take measures against accidents.

[Brief explanation of the drawing]

Figure 1 is a circuit configuration diagram of the circuit breaker according to this invention, Figure 2 is a characteristic curve diagram showing the relationship between "time and temperature rise" using the circuit current flowing into the heating element as a parameter, and Figure 3. is a characteristic curve diagram showing the relationship between "temperature rise and output voltage" of the overload detection temperature sensor. In the figure, 2 is an opening/closing mechanism, 3a to 3c are heating elements, 4a to 4c are temperature sensors for overload detection, and 5
1 is a first OR gate, 8 is an amplifier, 9 is an electromagnetic device, 11a to 11c are overload current detection sensors, 12 is a second OR gate, and 13 is a piezoelectric buzzer.

Claims (1)

[Scope of utility model registration request] A heating element that is placed in each phase of a circuit or disconnector is heated by the current flowing in each phase, and changes in the temperature rise that occur in the heating element are detected, and when an overload current flows, H A temperature sensor for overload detection that generates a level output voltage, and a temperature sensor placed in each phase of the circuit and circuit breakers, detects the overload current flowing in each phase, and immediately outputs an H level when the overload current flows. It is connected to the overload current detection sensor that generates voltage and the above-mentioned overload detection temperature sensor,
When the output voltage of even one of the overload detection temperature sensors reaches an H level voltage, an H level voltage appears on the output side.The first OR gate is connected to the overload current detection sensor, and the A second OR gate is connected to the first OR gate, and the output of this OR gate is connected to the second OR gate, which outputs an H-level voltage when even one of the output voltages of the load current detection sensor reaches an H-level voltage. an amplification device for amplifying the minute current that flows in when the voltage is at H level; an electromagnetic device that receives a trigger signal from a trigger circuit built into the amplification device to operate the opening/closing mechanism; and the second OR gate. connected to
A circuit breaker characterized by comprising an alarm device that issues an alarm when an overload current flows.