JPH07118256B2 - Current detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a current detection device for detecting that an abnormal current such as a short-circuit current or an overcurrent is applied to a main circuit.

[Background Art] A so-called electronic type circuit breaker has been conventionally operated in which a circuit breaker is operated by inserting a current transformer into a main circuit and exciting a polarized electromagnet based on the output of the current transformer. Is provided. In this type of circuit breaker, when an overcurrent of several times the rated current is applied to the main circuit, the control circuit detects that the current transformer output voltage has exceeded a specified value, and the control circuit output This excites the polarized electromagnet. Further, when a short circuit current of several tens of times or more of the rated current is applied to the main circuit, the polarized electromagnet is excited by directly supplying the current of the current transformer to the polarized electromagnet.

In order to realize a wiring breaker having such a structure, it is necessary to use, as a polarized electromagnet, a high-sensitivity one that responds quickly at low voltage (several msec or less). In addition, a current transformer that can obtain output linearity over a wide range of current values from a state in which an overcurrent is applied to the main circuit to a state in which a short-circuit current is applied is required. A current transformer that can output a high voltage to the extent that the polarized electromagnet can be operated when the electric path is energized is required. However, a polar electromagnet and a current transformer that satisfy these conditions are expensive and costly.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a coil for operating a plunger by a short-circuit current and an overcurrent flowing in a main circuit. An object of the present invention is to provide a miniaturized current detection device without using expensive parts by providing a coil for detection independently and combining both coils together with a plunger into one device.

DISCLOSURE OF THE INVENTION (Structure) A current detection device according to the present invention includes a plunger made of a magnetic material that is inserted into a coil block so as to move forward and backward and activates another device. The coil block has a return spring that biases in a protruding direction, and the coil block is a primary coil that is inserted into the main electric path and is excited to generate a magnetic force in a direction that pulls in the plunger by a current that is passed through the main electric path. A secondary coil magnetically coupled to the primary coil, and an attraction coil that is excited to generate a magnetic force in the direction of pulling the plunger based on the output of the secondary coil when an overcurrent is applied to the primary coil. Yes, when a short-circuit current flows in the main circuit, the primary coil pulls the plunger, and when an overcurrent flows in the main circuit, the primary coil is magnetized. By pulling the plunger attraction coil to be excited on the basis of the output of the engaged secondary coil, in which to avoid using a conventional such expensive polarized relays and current transformers.

Example 1 In the following example, an example in which the present invention is applied to a wiring breaker will be shown.

As shown in FIG. 5, the wiring breaker includes a current detection device 1 that is driven when an abnormal current such as an overcurrent or a short-circuit current flows in the main circuit, and a current detection device 1 that accumulates when the current detection device 1 is driven. The trip device 2 that releases the generated power to perform the trip operation, the contact device 3 that is momentarily opened by the trip device 2 performing the trip operation, and the arc generated when the contact device 3 is opened are extinguished. An arc extinguishing device 4 for arcing is housed in a body 5, and a handle 6 is set from the upper surface of the body 5 so as to accumulate power in the trip device 2.
Can project up and down freely.

The current detection device 1 is, as shown in FIGS. 1 to 3,
The solenoid is composed of a coil block 11, a yoke 12, a plunger 13, and a return spring 14. The coil block 11 is formed by winding a primary coil 11a, a secondary coil 11b, and a suction coil 11c around a coil bobbin 15, and the coil bobbin 15 includes three collar pieces 16 which are arranged in parallel with each other. A main bobbin 15a having the above, and an auxiliary bobbin 15b arranged on the lower surface side of the main bobbin 15a so as to face the collar piece 16. A cylindrical portion 15c is projected on the upper surface of the auxiliary bobbin 15b, and a cylindrical portion (not shown) projected on the lower surface of the main bobbin 15a is fitted to the cylindrical portion 15c, whereby the main bobbin 15a The flange piece 16 at the lower end and the auxiliary bobbin 15b are arranged in a separated form. A through hole that penetrates vertically in the center of the coil bobbin 15.
17 is formed, and the lower end of the plunger 13 is inserted into the through hole 17. A pair of guide ribs 18 are projectingly provided on the collar piece 16 at the upper end of the main bobbin 15a. The primary coil 11a is formed by winding an insulating coating wire between the collar piece 16 at the lower end of the main bobbin 15a and the auxiliary bobbin 15b, one end of which is connected to the terminal plate 52 on the power supply side and the other end of which is a contact device. 3 is connected to the movable contact 31. A terminal screw 53 is screwed onto the terminal plate 52. The secondary coil 11b is formed by winding an insulating coated wire between the flange piece 16 at the upper end of the main bobbin 15a and the flange piece 16 at the center. Further, the suction coil 11c is formed by winding an insulating coated conductor wire between the flange piece 16 at the center of the main bobbin 15a and the flange piece 16 at the lower end. The yoke 12 is formed by bending a magnetic plate into a substantially S shape, and rectangular through holes 12a and 12b through which the plunger 13 is inserted are formed in the upper horizontal piece and the middle horizontal piece. ing. Further, the coil block 11 is mounted between the middle horizontal piece and the lower horizontal piece with the primary coil 11a facing downward. The plunger 13 is made of a magnetic material, and has a hooking protrusion 13b formed at an upper end thereof and a spring storage recess 13a opened laterally at an upper and lower intermediate portion. The vertical width of the spring accommodating recess 13a is set to be approximately equal to the distance between the upper horizontal piece and the middle horizontal piece of the yoke 12. Spring receiving projections 13c, 13d are provided on the upper edge and the lower edge of the spring accommodating recess 13a,
The return spring 14 is mounted so that both ends are held by the spring receiving protrusions 13c and 13d. However, when the plunger 13 moves up and down, the return spring 14 is compressed, and the return force acts on the plunger 13. When no external force is applied to the plunger 13, the lower end of the plunger 13 is located above the lower horizontal piece of the yoke 12 and forms a gap D with the horizontal piece, and a part of It is in a state of being inserted into the coil 11a.

The trip device 2 includes a holding frame 21 fixed to a fixed position of the body 5, and the holding frame 21 includes a latch link 22, a locking lever 23, a cradle 24, a first link 25, and a second link.
The links 26 and the handle links 27, the link pins 22a to 25a for holding the links 22 to 27 in the frame 21 and connecting the links 22 to 27 to each other, the latch link 22, and the locking lever 23. A pair of compression springs 22b, 23b for urging each of them in a constant rotation direction and a tension spring 27b for urging the handle link 27 are mounted. Further, an interlocking bar 28, which is rotatably held by the body 5 at both ends in the axial direction, is provided, and the current detecting device 1 and the latch link 22 are interlocked via the interlocking bar 28. The trip device 2 is configured to maintain an equilibrium state in which the compression springs 22a, 23b and the tension springs 27b accumulate a force by the operation of the handle 6 protruding to the upper surface of the body 5 (the operation of tilting the handle 6 to the left in FIG. 5). When the plunger 13 of the current detecting device 1 moves downward, the interlocking bar 28 rotates, the equilibrium state of the trip device 2 collapses, and the accumulated power is rapidly released. is there.

The contact device 3 includes a movable contact 31 having a movable contact 32, a crossbar 35 holding the movable contact 31, and a contact pressure spring 33 interposed between the crossbar 35 and the movable contact 31. A fixed contact 34 integrally provided with the arc extinguishing device 4 described later is provided. One end of a braided wire 36 connected to one end of the primary coil 11a is connected to the movable contactor 31. Crossbar 35
Is made of an insulating material such as synthetic resin, and both ends in the axial direction are axially supported at fixed positions on the inner peripheral surface of the body 5, so that one end of the movable contact 31 can be vertically swung. Hold.
The movable contact 31 is connected to the second link 26 of the trip device 2 at the intermediate portion, and the contact device 3 is the trip device 2.
Is closed to the power, and the trip device 2
It is designed to open when the power accumulated in is released.

A fixed contact 34, which constitutes a contact with the movable contact 32, is provided on the upper surface of a fixed contact plate 41 of the arc extinguishing device 4, and an arc extinguishing grid device 42 is arranged at one end of the fixed contact plate 41. One end of an arc drive coil 43 is connected to an end of the fixed contact plate 41 opposite to the arc extinguishing grid device 42 with the fixed contact 34 interposed therebetween. The arc drive coil 43 is bent downward in a substantially U shape, and is arranged so that the fixed contact 34 is located at a corresponding position between the two leg pieces. The other end of the arc drive coil 43 is connected to a terminal plate 55 screwed with a terminal screw 56. The arc-extinguishing grid device 42 is a device in which a plurality of grid plates 44 made of a conductive magnetic material and arranged in parallel at a small distance in the vertical direction are held by a holding frame 45 made of an insulating material. However, when the movable contact 32 and the fixed contact 34 are opened and an arc is generated, the arc is applied to the arc extinguishing grid device 42 by the electromagnetic force acting between the magnetic field generated around the arc drive coil 43 and the arc current. The arc which is urged toward and introduced into the arc extinguishing grid device 42 is radiated by the grid plate 44 and rapidly extinguished.

As described above, the main electric path passing through the terminal plate 52, the primary coil 11a, the movable contact 31, the movable contact 32, the fixed contact 34, the fixed contact plate 41, the arc drive coil 43, and the terminal plate 55 is formed.

By the way, the primary coil that constitutes the coil block 11
11a, the secondary coil 11b, and the suction coil 11c are connected as shown in FIG. That is, it has been described above that the primary coil 11a is inserted into the main electric circuit including the contact device 3, but the secondary coil 11b is connected to the control circuit, and the suction coil 11c is connected to the output of this control circuit. Connected to be excited. The control circuit includes a resistor R that converts the output of the secondary coil 11b into a voltage, an amplifier circuit 61 that amplifies the voltage across the resistor R, an integrating circuit 62 that integrates the output of the amplifier circuit 61, and an output level of the integrating circuit 62 is predetermined. Discrimination circuit 63 that outputs an overcurrent detection signal when the value exceeds a value, an output circuit that obtains an ON output when an overcurrent detection signal output from the discrimination circuit 63 is received
64 and. The output circuit 64 is the suction coil 11c.
Is connected in series, and this series circuit is connected to the commercial power supply AC.

Therefore, the control circuit detects the counter electromotive force generated at both ends of the secondary coil 11b magnetically coupled to the primary coil 11a via the yoke 12 and the plunger 13, and when an overcurrent flows in the main circuit. Since the output level of the integration circuit 62 exceeds the set level of the determination circuit 63, the suction coil 11c is excited, and the plunger 13 is pulled downward against the spring force of the return spring 14.
As a result, the trip mechanism 2 operates and the contact device 3 opens. Further, when a short-circuit current flows in the main circuit, the plunger 13 is pulled downward only by the attractive force generated in the primary coil 11a, and the trip mechanism 2 operates in the same manner as in the case of overcurrent. Here, the lower end of the plunger 13 and the yoke 12
The primary coil 11 corresponding to the gap D formed between
Since a is provided, the magnetic flux generated by the primary coil 11a acts efficiently on the plunger 13, and the plunger 13 can be operated with high sensitivity with a relatively small number of turns. Further, since the suction coil 11c is disposed between the primary coil 11a and the secondary coil 11b, and the primary coil 11a and the secondary coil 11b are separated from each other, a magnetic circuit including the yoke 12 and the plunger 13 is provided. The amount of leakage flux passing through to the secondary coil 11b is reduced, short circuit current, pulse width is small, and peak value is large.
It has the advantage that it need only be provided on the output side of 11b.

[Advantages of the Invention] As described above, the present invention has a plunger made of a magnetic material that is inserted into a coil block so as to move forward and backward and activates another device in accordance with the forward and backward movements. The coil block has a return spring for urging, and the coil block is magnetically coupled to the primary coil and a primary coil that is excited so as to generate a magnetic force in a direction in which the plunger is drawn by a current that is passed through the main circuit. Secondary coil and a suction coil that is excited so as to generate a magnetic force in the direction of retracting the plunger based on the output of the secondary coil when an overcurrent is applied to the primary coil. When a short circuit current flows to
When the primary coil pulls the plunger, and when an overcurrent is flowing in the main circuit, the suction coil excited by the output of the secondary coil magnetically coupled to the primary coil pulls the plunger. There is an advantage that a current detecting device that operates with high sensitivity can be provided without using a polarized relay or a current transformer. In addition, the primary coil that detects the short-circuit current and pulls the plunger against the short-circuit current, the secondary coil that detects the over-current, and the suction coil that pulls the plunger at the time of over-current are integrated, and an external device is installed. Since the device including the plunger to be operated is one device, there is an advantage that the overall size can be reduced.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention, FIG. 2 is a sectional view of the same as above, FIGS. 3 (a) and 3 (b) are side views of the same, a plan view, and FIG. A circuit diagram and FIG. 5 are sectional views showing an example of a wiring breaker using the same as above. 1 is a current detection device, 11 is a coil block, 11a is a primary coil, 11b is a secondary coil, 11c is a suction coil, 13 is a plunger, and 14 is a return spring.

Claims (2)

[Claims] 1. A plunger comprising a magnetic body which is inserted into a coil block so as to be able to advance and retreat and which activates another device in accordance with the advance and retreat, and a return spring which urges the plunger in a direction to project from the coil block. , The coil block is
A primary coil that is inserted into the main circuit and is excited to generate a magnetic force that pulls the plunger by the current that flows in the main circuit, a secondary coil that is magnetically coupled to the primary coil, and an overcurrent flows through the primary coil. And a suction coil that is excited so as to generate a magnetic force in a direction in which the plunger is pulled in based on the output of the secondary coil when the current is detected. 2. The coil block is configured by interposing a suction coil between a primary coil and a secondary coil in a direction in which the plunger moves forward and backward, and the primary coil is arranged on the proximal end side of the plunger. The current detecting device according to claim 1, wherein