JPS636835Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to circuits and disconnectors.
For example, customers may have circuits where it would be difficult to automatically shut off the circuit, so in the event of an overload,
There is a demand for circuits and disconnectors that issue an alarm before operation. There is also a request to display at what amperage the circuit or disconnector trips.

Therefore, this device immediately generates an alarm with a buzzer when an overload current flows into a circuit or disconnector, and within the time stipulated in the JIS standard (for example, within 60 minutes for an overload current of 125%). , within a few minutes for overload current of 200%), for safety reasons,
automatically disconnecting the electrical circuit; and
Equipped with a maximum indicating ammeter equipped with a black driving pointer and a red highest remaining pointer, it indicates the maximum current flowing into the circuit breakers and breakers, and at the same time indicates the trip current of the circuit breakers and disconnectors using the red highest remaining pointer. By indicating the current even after the trip, the trip current can be determined.

An embodiment of this invention will be described below with reference to the drawings.

Fig. 1 is a circuit configuration diagram of a circuit breaker showing an embodiment of this invention, and Fig. 2 shows "time-temperature rise" 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 temperature sensor for overload detection.

In Figure 1, 1 is a switching 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 1 that occurs when the current is interrupted. It is a circuit breaker that consists of an arc extinguisher that extinguishes the arc, a terminal that connects electric wires and conductors, a contact that opens and closes the circuit, and a molded case that integrates these components.

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 has a trip-free function and a common tripping function for simultaneously engaging and disconnecting 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 temperature sensor for overload detection, for example, a solid state PCT thermistor is connected to the heating element 3.
Temperature detection elements a to 3c are used. This element exhibits high linearity as the resistance changes with temperature changes, and can be used over a wide range of -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 increases to the operating temperature after time t125 and t200.
It becomes T _A and outputs an output voltage of 1.3V, which is the threshold value. In other words, the H level output voltage is ORed as described below.
Supplied to the input side of the gate. In addition, in Figure 2, if the current flowing through each phase is 100% or less, the temperature rise of the heating element is lower than the operating temperature T _A ,
Since the temperature is T _B , the output voltage is lower than the threshold value (1.3V), so the L level output voltage is supplied to the input side of the OR gate described later. 5 is the first
At the OR gate, the above temperature sensor 4 for overload detection
If the voltages on the input sides A, B, and C supplied from a to 4c are all L-level voltages, an L-level voltage will appear on the output side D, and no minute current will flow in the amplifier 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 amplifier 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
Overload current detection sensors 11a to 11c are connected to the second OR gate to which the output voltage of c is applied to the input side.
If all the voltages on the input side supplied by the input side are L level voltages, 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 will appear on the output side. 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.

14 are overload current detection sensors 11a to 11
This is a maximum current detection circuit connected to c and detects the largest current value of each phase. Reference numeral 15 denotes an ammeter with a maximum indication connected to the maximum current detection circuit 14, and the return of the black driving pointer and the red highest remaining pointer to the driving pointer position is manual.

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 6
a~6c → heating element 3a~3c → load side terminal 7a~
It is supplied to the load electric motor 10 through 7c. When an overload current flows through this circuit, the heating elements 3a to 3
c 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. For 100% current, even if the current is applied continuously, the temperature rise will be the operating temperature T _A
The temperature below is T _B. But 125%
When current is applied continuously, the operating temperature reaches T _A after t125 hours, and when 200% current is applied continuously, it reaches t200.
After some time, the operating temperature reaches T _A. Note that this relationship is generally said to be similar to the thermal characteristics of the electric motor 10 as a load. When the thermistor element reaches the operating temperature T _A , the overload detection temperature sensor 4a
From ~4c, the H level output voltage which is the threshold value is
Supplied to input sides A, B, and C of 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.

At the same time, the current value of each phase detected by the maximum current detection circuit 14 is displayed by the maximum indicating ammeter 15. That is, when a circuit current flows through the circuit breaker 1, the overload current detection sensors 11a to 11c provided in each phase detect the circuit current. The maximum current detection circuit 14 detects the maximum value of the circuit currents of each phase, and the maximum indicating ammeter 15 indicates the current value. When an overload current flows through the circuit breaker 1, the maximum indicating ammeter 15 indicates the value, but if the circuit breaker trips after a certain period of time, the red highest remaining needle indicates the trip current. Since it indicates the trip current even if the power is lost after the circuit or disconnector trips.

As described above, according to this invention, when an overload current flows into a circuit or a circuit breaker, the overload current is immediately detected by the overload current detection sensor, and the OR
Due to the function of the gate, an H level voltage appears on its output side, and the piezoelectric buzzer generates an alarm. On the other hand, if an overload current flows through a circuit or disconnector, the circuit or disconnector will automatically trip after a certain period of time for safety reasons, but the red highest remaining needle on the maximum indicating ammeter indicates the trip current. is instructing. Therefore, the trip current is not known and does not become a problem, and accident countermeasures can be taken promptly.

[Brief explanation of 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" with 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 temperature sensor for overload detection. 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, 13 is a piezoelectric buzzer, 14 is a maximum current detection circuit, and 15 is a This is an ammeter with the highest indication.

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
It is connected to an alarm device that issues an alarm when an overload current flows, and to the above-mentioned overload current detection sensor.
A maximum current detection circuit that detects the largest current value of each phase, and an ammeter with maximum indication that is connected to the maximum current detection circuit and indicates the maximum current flowing through the circuit and is equipped with a maximum remaining needle function. A circuit breaker characterized by the following: