JPS61271730A - Display unit for circuit breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a circuit breaker having a static tripping device, and a circuit having a function of indicating whether the main circuit contacts are open/closed and a function of transmitting an open/closed status signal to an external circuit. The present invention relates to a display device for a circuit breaker.

[Technical Preface to the Invention] A static tripping device for a circuit breaker detects the main circuit current using a current transformer, rectifies the detected current, and compares the DC level with a reference value in a control circuit, As a result, when it is determined that there is a short-circuit current, a trip signal is output, and the tripping coil of the main circuit contact is energized and opened.

Generally, such a circuit breaker is provided with an indicator that indicates the open/closed state of the main circuit contacts.

This conventional display consists of a fixed iron core that is magnetically biased by a permanent magnet, a movable iron core with a display section that is attracted to the fixed iron core by a bias magnetic flux, and an excitation coil that is installed on the fixed iron core and cancels out the bias magnetic flux. The operation is as follows. In other words, if the movable core is always attracted to the fixed core by bias magnetic flux and the display section is hidden inside the display case, and in this state a short circuit current flows in the main circuit and a trip signal is output, ,
Due to this trip signal, the excitation coil is also excited at the same time as the tripping coil, canceling the bias magnetic flux of the fixed iron core, separating the movable iron core, and causing the display section to protrude outside the case.
This indicates the open state of the main circuit contacts.

[Problems with Background Art] However, in the conventional devices as described above, even if the open/closed state of the main circuit contacts can be displayed on the circuit breaker side, the display cannot be confirmed from an external circuit, for example, from a distance. Another disadvantage is that it cannot meet the requirement to send display signals to external circuits as interlock signals. In order to make this possible, it would be possible to provide an auxiliary contact mechanism operated by the movable core of the display, but
For this purpose, not only a contact mechanism but also an interlocking mechanism is required, which makes the display large and difficult to incorporate into a circuit breaker where space is limited.

[Object of the Invention] An object of the present invention is to provide a display device for a circuit breaker in which a switch element corresponding to the open/closed state of the main circuit contacts can be provided on the display side, and there is no need to increase the volume of the display device. It is in.

[Summary of the Invention] In the circuit according to the present invention, the 1lFi display is excited in the direction of canceling the bias magnetic flux by the display signal outputted in synchronization with the trip signal to the stator core magnetically biased by the permanent magnet. In addition to providing a coil, a movable core for display that is attracted to the fixed core is also provided, and a magnetically sensitive element is also provided in the magnetic path on the fixed core side, so that the element has a substantial on/off action to connect to the external circuit. It is designed to be able to output open/close state signals of the main circuit contacts.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 2, a main circuit 1 is configured to supply power from a power source 2 to a motor 3, which is a load, via a circuit breaker 4. This main circuit 1 is provided with a current transformer 5, and the output of this current transformer 5 is passed through a full-wave rectifier circuit 6 to a control voltage Ill.
! 17 and 8 as a control power source. This system? A resistor 9 for current-voltage conversion is installed between the li source lines 7 and 8.
and a Zener diode 10 are connected in series. As a result, the control circuit 11 is provided with a constant voltage power supply by the Zener diode 10, and the voltage 5 between the terminals of the resistor 9 is
The output signal is given as an overcurrent detection signal to the main circuit 1.

That is, when an overcurrent such as a short-circuit current flows in the main circuit 1, this control circuit 11 determines this by comparing the magnitude of the voltage Eo between the terminals of the resistor 9 with a reference value and outputs it to the base of the transistor 12. Tripping coil 1 by applying trip signal S1
3 is excited, thereby tripping the circuit breaker 4. At this point, the transistor 14 also receives the trip signal S1.
The display 15 is turned on by a signal generated in synchronization with the display 15. In addition, in FIG. 1, 16 is a smoothing capacitor.

Next, this display 15, which is the direct object of the present invention, will be explained with reference to FIG. That is, a fixed core device 118 is disposed within the case 17, and this includes a permanent magnet 19, first and second fixed cores 20 and 21 erected at both end portions of the permanent magnet 19, and an intermediate portion. Guide rod 22 erected on
It consists of A movable iron core 23 is provided on the guide rod 22 together with a compression coil spring 24 so as to be movable up and down, and a display protrusion 23a serving as a display portion is provided on the upper surface of the case 17 on the approximately medium heat of the upper surface of the movable iron core 23 in the figure. It is provided so as to be able to penetrate through the opening 25 formed in the.

The permanent magnet provides a magnetic bias to the fixed core 20.21. However, an excitation coil 26 for canceling the bias magnetic flux is provided on the first fixed core 20, and a magnetic sensing element, such as a magnetoresistive element 27, is provided as a switch element in the magnetic path of the second rotary core 21, for example at its tip. is connected at both ends to an external circuit, such as a remote display 28, so that it acts as a kind of output contact. When a magnetic field is applied to this magnetoresistive element 27, the electrical resistance increases due to the magnetoresistive effect, resulting in a state similar to a switch off, and when the magnetic field is removed, the electrical resistance decreases, resulting in a state similar to a switch on. Further, the excitation coil 26 is connected to the transistor 14.
is connected in series with.

Next, to explain the effect of the above configuration, the excitation coil 2
6 is li? ! ! When the movable iron core 23 is in the state of
The first one resists the repulsive force of . It is attracted to the second fixed iron core 20.21.

Now, in this state, if the overcurrent state of the main circuit 1 is detected by the control circuit 11 and the transistor 12 is turned on and the tripping coil 13 is energized, as mentioned above, the transistor 14 is also turned on at the same time, so it is not excited. Coil 26 is energized. Then, the bias magnetic flux generated by the permanent magnet 19 is canceled, and the movable core 23 separates from the fixed core 20.21 due to the repulsive force of the compression coil spring 24. This causes the display protrusion 23a to largely protrude outside the case 17, thereby causing the main circuit Displays that contact 4 is in an open state.

In such a display operation, when the circuit breaker 4 is in an open state, that is, when the movable core 23 is connected to the fixed core 20.
When the magneto-resistance element 27 is attracted to the magnet, the magnetic resistance element 27 is in a high-resistance state because it receives a large amount of magnetic flux. On the other hand, when the main circuit contact 4 is open, that is, when the movable iron core 23 is separated from the fixed iron core 20, 21, the magnetic resistance element 27 receives less magnetic flux, so it is electrically conductive. As a result, a kind of switch-on signal is given to the remote display unit 28 to perform a display operation.

It should be noted that the present invention is not limited to the above embodiments, and in particular, a magnetically sensitive element may be used as an interlock switch element for an external circuit, and it goes without saying that the magnetically sensitive element is not limited to that described above. be.

[Effects of the Invention] As is clear from the above description, the present invention provides the following effects. That is, since the configuration is such that a magnetically sensitive element is disposed in the magnetic flux path of the fixed core of the display as a switch element that provides a display signal from the display to an external circuit, the contact switch mechanism and its interlocking mechanism with the movable core are There is almost no increase in the volume of the display compared to the case where it is provided. Such compactness can be easily maintained even when a large number of switch elements are desired.

Therefore, it is most suitable as an indicator to be incorporated into a circuit breaker having a stationary drawer device whose main purpose is to be small.

Of course, since this switching element is of a non-contact type that mediates magnetism, high reliability can be maintained over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a display device showing one embodiment of the present invention, and FIG.
The figure is a wiring diagram of the overcurrent protection circuit. In the figure, 1 is the main circuit, 3 is the motor, 5 is the current transformer, 11 is the control circuit, 13 is the tripping coil, 15 is the display, 19 is the permanent magnet, 20.21 is the first . The second fixed iron core, 23 is a movable iron core, 23a is a display projection (display part), 26 is an excitation coil, and 27 is a magnetoresistive element (magnetic sensing element). Applicant Toshiba Corporation Figure 1

Claims (1)

[Claims] 1. A fixed iron core, a permanent magnet provided on the fixed iron core to magnetically bias it, a movable iron core having a display section and provided so as to be attracted to the fixed iron core by bias magnetic flux, and the fixed iron core side 1. A display device for a circuit breaker, comprising: an excitation coil that is provided in an excitation coil and is excited in a direction to cancel the bias magnetic flux; and a magnetically sensitive element disposed in a magnetic flux path passing through the fixed iron core.