JP5981766B2 - electromagnetic switch - Google Patents

Description

  The present invention relates to an electromagnetic switch having a movable contact and a pair of fixed contacts inserted in a direct current path, and the open contact state where the fixed contact and the movable contact face each other while maintaining a gap, and the two are in contact with each other. It is made possible to detect a closed state.

Conventionally, in an electromagnetic switch such as an electromagnetic relay or an electromagnetic contactor, a pair of fixed contacts are arranged in a sealed container at a predetermined interval, and the movable contact is connected to or separated from the pair of fixed contacts. It arrange | positions so that it is possible (for example, refer patent document 1).
In the released state where the movable contact is opposed to the pair of fixed contacts via a predetermined gap, the DC current path between the pair of fixed contacts is open. On the other hand, when the movable contact is driven by a driving unit such as an electromagnet device and is brought into contact with the pair of fixed contacts, a direct current path is formed between the pair of fixed contacts to close the pole. It becomes a state.

JP-A-9-259728

However, in the conventional example described in Patent Document 1, a pair of fixed contacts and a movable contact disposed so as to be able to come in contact with and away from the pair are arranged in a sealed container. Since the movable state of the contact cannot be visually recognized from the outside, the movable contact does not operate when it is in the input state, or the movable contact does not separate from the pair of fixed contacts when it is in the released state. There is an unresolved issue that cannot be confirmed.
Accordingly, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and is an electromagnetic switch capable of monitoring whether or not a movable contact is in contact with a pair of fixed contacts. The purpose is to provide.

  In order to achieve the above object, a first aspect of an electromagnetic switching device according to the present invention includes a pair of fixed contacts inserted in a DC current path fixedly arranged at a predetermined interval in a contact storage case, A movable contact disposed so as to be able to contact and separate from the pair of fixed contacts and an electromagnet unit for moving the movable contact are provided. The electromagnetic switching device measures a pair of capacitors individually connected to each of the pair of fixed contacts, a resistor connected to the other end of the pair of capacitors, and impedances at both ends of the resistor, Contact for detecting an open state in which the movable contact is opposed to the pair of fixed contacts via a predetermined gap and a closed state in which the movable contact is in contact with the pair of fixed contacts A state detection unit.

  According to the first aspect, the capacitors are individually connected to the pair of fixed contacts that open and close the DC current path, and the resistors are connected to the other ends of these capacitors. By measuring the impedance at both ends of this resistor, the contact state and non-contact state of the movable contact with respect to the pair of fixed contacts can be accurately detected.

Moreover, the 2nd aspect of the electromagnetic switch which concerns on this invention is comprised by the dielectric material ring which the said capacitor fits into the edge part which protrudes from the said contact storage case of a pair of said stationary contact.
According to the second aspect, the capacitor can be formed by fitting the dielectric ring to the pair of fixed contacts, and the impedance can be adjusted by adjusting the thickness of the dielectric ring. .

Moreover, the 3rd aspect of the electromagnetic switch which concerns on this invention is adjusted so that the synthetic | combination impedance of a pair of said capacitor | condenser and the impedance of the said resistor may correspond.
According to the third aspect, the movable contact is in contact with the pair of fixed contacts with respect to the impedance when the movable contact is in contact with the pair of fixed contacts. In some cases, the value can be halved.

  According to a fourth aspect of the electromagnetic switch of the present invention, the contact state detection unit includes a pulse signal generation unit having one end connected to one end of the resistor and the other end connected to the ground, and the pulse signal. A voltage limiting resistor connected between the generator and the ground and the other end of the resistor, and a comparator for comparing a potential at a connection point of the resistor and the voltage limiting resistor with a reference potential. Yes.

  According to the fourth aspect, in the open state where the movable contact is not in contact with the pair of fixed contacts, the pulse voltage of the predetermined frequency generated by the pulse signal generator is divided between the resistor and the voltage limiting resistor. It becomes the value. From this open state, when the movable contact is brought into contact with a pair of fixed contacts, a series circuit of a pair of capacitors is connected in parallel to the resistor, and the impedance at both ends of the resistor is reduced. To do. By detecting this change in impedance by the comparison unit, it is possible to obtain a contact contact detection signal representing an open state and a closed state.

  According to the present invention, a pair of fixed contacts are individually connected to both ends of a resistor via a capacitor, so that the contact state of the movable contact with respect to the pair of fixed contacts of the resistor can be changed by impedance change at both ends of the resistor. It can be detected accurately.

It is sectional drawing which shows 1st Embodiment at the time of applying this invention to an electromagnetic contactor. It is a circuit block diagram which detects the opening / closing state of the contact mechanism comprised with a movable contact and a pair of fixed contacts, (a) is a circuit block diagram of an open state, (b) is a circuit block diagram of a closed state It is. It is a circuit diagram which shows an impedance change detection circuit. It is a figure which shows the structural example of a capacitor | condenser, (a) is a disassembled perspective view, (b) is a perspective view which shows the mounting state of a capacitor | condenser, (c) is explanatory drawing of the capacity | capacitance adjustment of a capacitor | condenser. It is a circuit diagram which shows the other example of a contact state detection part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a first embodiment when the contact device of the present invention is applied to an electromagnetic contactor as an electromagnetic switch. In FIG. 1, 1 is an exterior case made of, for example, a synthetic resin. The exterior case 1 includes a bottomed cylindrical body 1a whose lower end surface is opened and a bottom plate 1b that closes the lower end surface of the bottomed cylindrical body 1a.

In the outer case 1, a contact device 2 having a contact mechanism and an electromagnet unit 3 as an electromagnet device for driving the contact device 2 are accommodated in series with the electromagnet unit 3 disposed on the bottom plate 1 b. Yes.
The contact device 2 has a contact storage case 4, which is made of ceramics, synthetic resin or the like and has a bowl-shaped body 4a having a lower end opened, and a metal joining member that is tightly fixed to the open end surface. 4b and the metal cylinder 4c which covers the side surface of the bowl-shaped body 4a. The joining member 4b is brazed to the upper surface of the upper magnetic yoke 22 of the electromagnet unit 3 and fixed in an airtight state by welding or the like.

On the upper surface of the bowl-shaped body 4a, through holes 5a and 5b having a circular cross section are provided in the longitudinal direction at a predetermined interval, and a pair of, for example, copper fixed contacts 6a and 6b are inserted into the through holes 5a and 5b. And fixed by an adhesive or the like.
Each of the fixed contacts 6 a and 6 b is composed of an upper-side large-diameter head 7 and a lower-side small-diameter cylindrical portion 8 that is coaxially connected to the large-diameter head 7.

These fixed contacts 6a and 6b are fixed so that the through-holes 5a and 5b are sealed with an adhesive or the like to the rod-shaped body 4a in a state where the small-diameter cylindrical portion 8 is inserted into the through-holes 5a and 5b of the rod-shaped body 4a. ing.
Further, the contact device 2 is arranged so that the movable contact 11 can come in contact with and separate from a lower end surface of the small diameter cylindrical portion 8 of the fixed contacts 6a and 6b with a relatively narrow predetermined gap. The movable contact 11 is attached to the contact holder 13 by being urged upward by a contact spring 14. The contact holder 13 is connected to a movable plunger 25 of the electromagnet unit 3 described later and is driven in the vertical direction.

Further, external connection terminal plates 15a and 15b are screwed to the large-diameter heads 7 of the fixed contacts 6a and 6b.
The electromagnet unit 3 has a U-shaped magnetic yoke 21 as viewed from the side, and a cylindrical portion 21 b having a lower end opened at the center of the bottom plate portion 21 a of the magnetic yoke 21. The upper surface side of the magnetic yoke 21 is connected by the upper magnetic yoke 22.

  A coil holder 24 around which an exciting coil 23 is wound is mounted on the outer peripheral surface of the cylindrical portion 21b of the magnetic yoke 21, and a bottomed cylindrical shape in which a movable plunger 25 is slidably mounted on the inner peripheral surface of the cylindrical portion 21b. A cap 26 is provided. A rubber seat 27 that contacts the bottom surface of the movable plunger 25 and absorbs an impact when the movable plunger 25 is lowered is disposed on the bottom surface of the cap 26.

The movable plunger 25 is fitted with a connecting shaft 28 at the center, and the head of the connecting shaft 28 extends upward through a through hole 29 formed in the upper magnetic yoke 22 and is connected to the contact holder 13. Yes.
Further, a spring insertion hole 30 is formed around the connecting shaft 28 of the movable plunger 25, and a return spring 31 for biasing the movable plunger 25 downward is mounted between the spring insertion hole 30 and the upper magnetic yoke 22. Yes.

Then, hydrogen gas, nitrogen gas, and a mixture of hydrogen and nitrogen are contained in a sealed space constituted by the contact housing case 4 constituted by the flange 4a, the joining member 4b and the metal cylinder 4c, the upper magnetic yoke 22 and the cap 26. Gas, air, arc extinguishing gas such as SF ₆ is enclosed.
The open contact state where the movable contact 11 is opposed to the pair of fixed contacts 6a and 6b through a predetermined gap, and the movable contact 11 is cut between the pair of fixed contacts 6a and 6b. The closed contact state is detected by the contact state detection unit 50, as shown in FIG.

As shown in FIG. 2, one end of capacitors 42A and 42B is individually connected to the pair of fixed contacts 6a and 6b to detect the contact state between the pair of fixed contacts 6a and 6b and the movable contact 11, respectively. Yes. A resistor 43 is connected between the other ends of the capacitors 42A and 42b. Measurement terminals 44A and 44B are led out from both ends of the detection resistor 43.
The contact state detection unit 50 is connected to the measurement terminals 44A and 44B, and the contact state detection unit 50 detects the impedance of both ends of the detection resistor 43 to detect the contact state of the movable contactor 11. .

As shown in FIG. 3, the contact state detection unit 50 includes a connection terminal 51A connected to the measurement terminal 44A and a connection terminal 51B connected to the measurement terminal 44B.
A pulse signal generator 52 that outputs a pulse voltage signal is interposed between the connection terminal 51A and the ground. A voltage limiting resistor 53 is interposed between the connection point between the pulse signal generator 52 and the ground and the connection terminal 51B. An inverting input terminal of a comparator 54 as a comparison unit is connected to a connection point between the voltage limiting resistor and the connection terminal 51B. A reference voltage Vb is supplied to the non-inverting input terminal of the comparator 54.

Therefore, when the voltage Vin input from the output terminal of the comparator 54 to the inverting input terminal is higher than the reference voltage Vb input to the non-inverting input terminal, the low-level contact state detection signal Vc is output, and conversely the inverting input. When the voltage supplied to the terminal is lower than the reference voltage Vb supplied to the non-inverting input terminal, a high level contact state detection signal Vc is output.
The contact state detection signal Vc output from the comparator 54 is supplied to, for example, a diode drive circuit 57 that drives the light emitting diode 56 via an inverter 55 that inverts the level. The diode drive circuit 57 uses the contact state detection signal Vc. The light emitting diode 56 is turned on when is at a low level.

Next, the operation of the above embodiment will be described.
Assume that the external connection terminal plate 15a is connected to a DC power supply source that supplies a large current, for example, and the external connection terminal plate 15b is connected to a load.
In this state, it is assumed that the excitation coil 23 in the electromagnet unit 3 is in a non-energized state and no excitation force for moving the movable plunger 25 is generated by the electromagnet unit 3. In this state, the movable plunger 25 is urged downward by the return spring 31 away from the upper magnetic yoke 22 and comes into contact with the rubber seat 27. For this reason, the movable contact 11 supported by the contact holder 13 connected to the movable plunger 25 via the connection shaft 28 sandwiches a predetermined gap from the lower end surface of the small diameter cylindrical portion 8 of the fixed contacts 6a and 6b. The contact device 2 is in an open (released) state.

  When the exciting coil 23 of the electromagnet unit 3 is energized from the open state of the contact device 2, an exciting force is generated by the electromagnet unit 3, and the movable plunger 25 is pushed up against the return spring 31. Accordingly, the contact holder 13 connected to the movable plunger 25 via the connecting shaft 28 moves upward, and the movable contact 11 contacts the bottom surface of the small-diameter cylindrical portion 8 of the fixed contacts 6a and 6b. Contact with a contact pressure of 14.

For this reason, a closed state (input) state in which a large current i of the external power supply source is supplied to the load through the external connection terminal plate 15a, the fixed contact 6a, the movable contact 11, the fixed contact 6b, and the external connection terminal plate 15b. It becomes.
When the current supply to the load is cut off from the closed state of the contact device 2, the voltage application to the exciting coil 23 of the electromagnet unit 3 is stopped.

  As a result, the exciting force that moves the movable plunger 25 upward by the electromagnet unit 3 disappears, and the movable plunger 25 is lowered by the biasing force of the return spring 31. When the movable plunger 25 is lowered, the contact holder 13 connected via the connecting shaft 28 is lowered, and the movable contact 11 is fixedly contacted while the contact spring 14 is applied with the contact pressure accordingly. It is in contact with the children 6a and 6b. After that, when the contact pressure of the contact spring 14 disappears, the movable contact 11 is in an open state in which it is separated downward from the fixed contacts 6a and 6b.

In this open state, an arc is generated between the stationary contacts 6 a and 6 b and the movable contact 11. This arc is greatly extended by an arc extinguishing permanent magnet (not shown) and extinguished.
In this way, by controlling the exciting coil 23 of the electromagnet unit 3 to the non-energized state and the energized state, the contact device 2 moves away from the pair of fixed contacts 6a and 6b while the movable contact 11 maintains a predetermined gap. And the closed contact state in which the movable contact 11 is in contact with the pair of fixed contacts 6a and 6b.

When the contact device 2 is in the open state, as shown in FIG. 2 (a), since the pair of fixed contacts 6a and 6b are open, the impedance between the measurement terminals 44A and 44B is a resistance. 43 impedance R only.
On the other hand, when the contact device 2 is in a closed state, as shown in FIG. 2B, the pair of fixed contacts 6a and 6b are electrically connected by the movable contact 11, so that the resistor R is in parallel. And a parallel circuit with capacitors 42A and 42B. Therefore, assuming that the impedance of the capacitors 42A and 42B is Rc, the impedance between the measurement terminals 44A and 44b is R × 2Rc / (R + 2Rc), which is smaller than the impedance R of the resistor 43.

At this time, the impedance Rc of the capacitors 42A and 42B is set so that the frequency of the pulse voltage signal of the pulse signal generator 42 is f and the capacitance of the capacitors 42A and 42B is C.
Rc = 1 / 2πfC
It becomes.
Here, when at least one of the capacitance C of the capacitors 42A and 42B and the frequency f of the pulse voltage signal is adjusted so that the combined impedance 2Rc of the capacitors 42A and 42B matches the impedance R of the resistor 43, the impedance at the time of closing is R / 2, and can be half of the impedance R at the time of opening.
These can be summarized as shown in Table 1 below.

For this reason, when the contact state detection unit 50 outputs a pulse voltage signal having a predetermined frequency from the pulse signal generation unit 52 in the open state of the contact device 2, the pulse voltage signal at this time includes the resistor 43 and the voltage limiting resistor 53. Is supplied to the inverting input terminal of the comparator 54.
Here, when the contact device 2 is in a closed state, the impedance becomes smaller than the impedance at the time of opening as described above. For this reason, the voltage input to the inverting input terminal of the comparator 54 increases.

Therefore, the reference voltage Vb supplied to the non-inverting input terminal of the comparator 54 is higher than the voltage supplied to the inverting input terminal at the time of opening and lower than the voltage supplied to the inverting input terminal at the time of closing. Is set.
For this reason, when the contact device 2 is opened, the voltage Vin supplied to the inverting input terminal of the comparator 54 becomes lower than the reference voltage Vb, so that the comparator 54 detects a high-level contact state indicating the open state. A signal Vc is output.
On the other hand, when the contact device 2 is closed, the voltage Vin supplied to the inverting input terminal of the comparator 54 is higher than the reference voltage Vb. Therefore, the low level contact state detection signal indicating the closed state from the comparator 54. Vc is output.

  Therefore, the contact state detection signal Vc output from the comparator 54 is inverted by the inverter 55 and supplied to, for example, the drive circuit 57 that drives the light emitting diode 56, thereby turning off the light emitting diode when the electrode is opened and emitting light when the electrode is closed. The diode can be turned on, and the contact state of the movable contact 11 can be accurately displayed. For this reason, it is possible to accurately monitor the contact state of the movable contactor 11 outside the electromagnetic contactor.

  Further, since the capacitors 42A and 42B are individually connected to the pair of fixed contacts 6a and 6b as an impedance measurement circuit between the pair of fixed contacts 6a and 6b, the pair of fixed contacts 6a and 6b is fixed by the capacitors 42A and 42B. The direct current flowing through the contacts 6a and 6b can be cut off, and the high current can be prevented from affecting the contact state detection unit 50.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, the configuration of the capacitor connected to the pair of fixed contacts 6a and 6b is changed.
That is, in 2nd Embodiment, as shown to Fig.4 (a), an internal diameter is equal to or slightly smaller than the outer diameter of the edge part which protrudes from the exterior case 1 of a pair of fixed contacts 6a and 6b. Then, flat cylindrical dielectric rings 62A and 62B having electrode portions 61 formed on the outer peripheral surface are prepared.

  And these dielectric rings 62A and 62B are fitted to the outer peripheral surface of the edge part which protrudes from the exterior case 1 of a pair of fixed contacts 6a and 6b, as shown in FIG.4 (b). Thereby, the stationary contacts 6a and 6b that contact the inner peripheral surfaces of the dielectric rings 62A and 62B, the dielectric rings 62A and 62B, and the electrode portion 61 formed on the outer peripheral surfaces of the dielectric rings 62A and 62B, A capacitor is formed.

Then, the resistor 63 is connected between the electrode portions 61 of the dielectric rings 62A and 62B, and the measurement terminals 64A and 64B are derived, whereby the impedance measurement circuit configuration similar to that of the first embodiment described above is obtained. be able to.
In this case, as shown in FIG. 4C, the capacitance C can be adjusted by adjusting the thickness of the dielectric rings 62A and 62B.

Other configurations are the same as those of the first embodiment described above.
As described above, according to the second embodiment, the dielectric rings 62A and 62B having the electrode portions 61 formed on the outer peripheral surface are fitted to the pair of fixed contacts 6a and 6b to form a capacitor. Therefore, it is not necessary to connect a single capacitor to the pair of fixed contacts 6a and 6b as in the first embodiment described above, and the dielectric rings 62A and 62B are simply fitted to the pair of fixed contacts 6a and 6b. Since it is only necessary to combine them, the entire configuration can be simplified and the size can be reduced.

Moreover, the resistor 63 is connected in advance to the electrode parts 61 of the dielectric rings 62A and 62B, and the unit is formed so that the measurement terminals 44A and 44B are led out, so that the impedance measurement part can be assembled more easily. Can do.
In the first and second embodiments, the case where the impedance change detection circuit is configured as shown in FIG. 3 has been described. However, the present invention is not limited to this, and the automatic balancing bridge circuit shown in FIG. It can also be applied. In this automatic balancing bridge circuit, as shown in FIG. 5, a sine wave signal generator 70 for generating a sine wave AC voltage is connected to a connection terminal 71A, and a feedback resistor 72 is connected to the connection terminal 71B between the output side and the inverting input side. The connection point of the inverting input terminal of the inverting amplifier 74 composed of the operational amplifier 73 and the feedback resistor 72 is connected. The non-inverting input terminal of the operational amplifier 73 is grounded.

  Then, the voltage V1 of the connection terminal 71A and the output voltage V2 of the operational amplifier 73 are supplied to the detection unit 75. In this detection unit 75, the voltages V1 and V2 are obtained as complex numbers using the phase information of the sine wave signal generation unit 70, and the ratio (V1 / V2) of these voltages is multiplied by the resistance value Rr of the feedback resistor 72 for measurement. A contact state detection signal representing the contact state of the movable contact 11 by calculating the impedance between the terminals 44A and 44B and comparing the calculated impedance with a preset impedance threshold that can be determined. Obtain Vc.

  Moreover, in the said 1st and 2nd embodiment, although the case where the light emitting diode 56 was driven based on the contact state detection signal Vc output from the contact state detection part was demonstrated, it is not limited to this. Other display elements may be driven, and contact state detection signals are supplied to the control panel that controls the opening and closing of the electromagnetic switch to display the contact state on the display screen or to the abnormality detection circuit Then, abnormality determination of the electromagnetic switch may be performed.

Moreover, in the said 1st and 2nd embodiment, although the case where the contact storage case 4 was comprised with the bowl-shaped body 4a, the joining member 4b, and the metal cylinder 4c was demonstrated, it is not limited to this, An insulating cylinder may be arranged inside the metal bowl-like body, and any configuration can be adopted.
Furthermore, in the said embodiment, although the case where gas was enclosed with the contact storage case 4 was demonstrated, it is not limited to this, When the electric current value to interrupt | block is small, enclosure of gas can be abbreviate | omitted. .

Moreover, in the said embodiment, although the case where the movable contact 11 opposed the fixed contacts 6a and 6b from the lower side was demonstrated, it is not limited to this, The contact part of the fixed contacts 6a and 6b is used. The movable contactor 11 may be disposed below the contact housing case 4 and opposed to the contact parts from above.
Furthermore, the configuration of the electromagnet unit 3 is not limited to the above embodiment, and any configuration can be applied as long as the contact holder 13 can be moved by electromagnetic force.
Furthermore, although the case where the present invention is applied to an electromagnetic contactor has been described in the above embodiment, the present invention is not limited to this, and the present invention can be applied to an electromagnetic relay or an electromagnetic switch having another configuration. it can.

  DESCRIPTION OF SYMBOLS 1 ... Exterior case, 2 ... Contact device, 3 ... Electromagnet unit, 4 ... Contact storage case, 4a ... Gutter-like body, 4b ... Joining member, 4c ... Metal cylinder, 6a, 6b ... Fixed contact, 11 ... Movable contact Child, 12 ... arc foot movement promoting portion, 12a, 12b ... tapered surface, 13 ... contact holder, 14 ... contact spring, 15a, 15b ... external connection terminal plate, 21 ... magnetic yoke, 22 ... upper magnetic yoke, 23 ... Excitation coil, 24 ... coil holder, 25 ... movable plunger, 26 ... cap, 28 ... coupling shaft, 31 ... return spring, 42A, 42B ... capacitor, 43 ... resistance, 44A, 44B ... measurement terminal, 50 ... contact state detector , 51A, 51B ... connection terminal, 52 ... pulse signal generator, 53 ... voltage limiting resistor, 54 ... comparator, 56 ... light emitting diode, 57 ... diode drive circuit, 61 ... electricity Parts, 62A, 62B ... dielectric ring, 63 resistors, 64A, 64B ... measuring terminal, 70 ... sinusoidal signal generating section, 72 ... feedback resistor, 73 ... operational amplifier, 74 ... inverting amplifier, 75 ... detecting section

Claims (4)

A pair of fixed contacts inserted in a direct current path fixedly arranged in the contact storage case at a predetermined interval;
A movable contact disposed so as to be able to contact and separate with respect to the pair of fixed contacts;
An electromagnet unit for moving the movable contact;
A pair of capacitors individually connected to each of the pair of fixed contacts;
A resistor connected to the other end of the pair of capacitors;
An open state in which the movable contacts are opposed to the pair of fixed contacts through a predetermined gap by detecting impedances at both ends of the resistor, and the movable contacts on the pair of fixed contacts but it provided with a contact state detecting unit for detecting the closed state in contact,
An electromagnetic switch, wherein the combined impedance of the pair of capacitors and the impedance of the resistor are adjusted to match . The contact state detection unit includes a pulse signal generation unit having one end connected to one end of the resistor and the other end connected to the ground, and between the pulse signal generation unit and the ground and the other end of the resistor. 2. The electromagnetic switch according to claim 1, further comprising: a voltage limiting resistor connected to the first terminal, and a comparison unit that compares a potential at a connection point of the resistor and the voltage limiting resistor with a reference potential . A pair of fixed contacts inserted in a direct current path fixedly arranged in the contact storage case at a predetermined interval;
A movable contact disposed so as to be able to contact and separate with respect to the pair of fixed contacts;
An electromagnet unit for moving the movable contact;
A pair of capacitors individually connected to each of the pair of fixed contacts;
A resistor connected to the other end of the pair of capacitors;
An open state in which the movable contacts are opposed to the pair of fixed contacts through a predetermined gap by detecting impedances at both ends of the resistor, and the movable contacts on the pair of fixed contacts A contact state detection unit for detecting a closed state in contact with,
The contact state detection unit includes a pulse signal generation unit having one end connected to one end of the resistor and the other end connected to the ground, and between the pulse signal generation unit and the ground and the other end of the resistor. voltage limiting resistor and the resistance and conductive magnetic switch you characterized by comprising a comparison unit for comparing the potential with a reference potential of the voltage limiting resistor node coupled to. 4. The electromagnetic wave according to claim 1, wherein the capacitor is configured by a dielectric ring that is fitted to ends of the pair of fixed contacts protruding from the contact housing case. 5. Switch.

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