WO2014083770A1 - Electromagnetic switch - Google Patents

Description

electromagnetic switch

The present invention relates to an electromagnetic switch provided with a movable contact and a pair of fixed contacts inserted in a direct current path, and can easily detect whether the movable state of the movable contact is normal. Is.

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. I try to arrange it as possible.
In such an electromagnetic switch, it is necessary to detect whether or not the movable state of the movable contact is normal in order to ensure reliability.
For this purpose, for example, an electromagnetic switch is known in which an auxiliary contact is arranged on the bottom side near the main contact terminal, the drive shaft moves, and the movable auxiliary contact terminal is moved via a pusher to make the contact. (For example, refer to Patent Document 1).

US Pat. No. 7,944,333

However, in the conventional example described in Patent Document 1, an auxiliary contact is disposed on the bottom surface in the vicinity of the main contact terminal, and this auxiliary contact is pressed via a pusher by a drive shaft that moves the movable contact. Whether or not the movable contactor is movable is determined based on whether or not the auxiliary contact is placed in the sealed container in the same manner as the main contact terminal. The structure is complicated.

In addition, an auxiliary contact is placed near the main contact fixed terminal, and the size, number of contacts, and contact configuration are limited in order to insulate the main contact, and the interruption limit value is small and the contact life is short. There are also unsolved issues.
Furthermore, there is an unsolved problem that the auxiliary contact has a cantilever spring structure, the rigidity is weak, the gap size is large, and it is difficult to make a mirror contact.
Therefore, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and without performing gas-tight processing by magnetically detecting the movable state of the movable contact without using a contact. It is an object of the present invention to provide an electromagnetic switch that can easily determine a movable state.

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 with respect to the pair of fixed contacts, an electromagnet unit that moves the movable contact, and a movable state detection that detects a movable state of the movable contact as a magnetic change. And a movable state determining unit that determines whether or not the movable state of the movable contact is normal based on the detection result of the movable state detecting means.
According to a second aspect of the electromagnetic switch according to the present invention, the movable state detection unit includes a permanent magnet disposed on a movable iron core that moves the movable contact, and a magnetism that detects a change in magnetic flux of the permanent magnet. It consists of a sensor.
Moreover, the 3rd aspect of the electromagnetic switch which concerns on this invention is comprised by the search coil in which the said movable state detection part detects the induced voltage by the magnetic flux of the magnetic yoke of the said electromagnet unit.

According to the present invention, the movable state of the movable contact that contacts and separates from the pair of fixed contacts is magnetically detected by the movable state detection unit, and the movable state determination unit determines the movement based on the signal detected by the movable state detection unit. The movable state of the movable contact can be accurately determined.
For this reason, the movable state of the movable contact can be detected outside the contact storage case for storing the movable contact, and the movable state can be performed without lending the sealing process even when the contact storage case is gas-sealed. Can be detected.

It is sectional drawing of the release state which shows 1st Embodiment at the time of applying this invention to an electromagnetic contactor. It is a time chart at the time of the release start of 1st Embodiment, (a) is a figure which shows the detection voltage change of a magnetic sensor, (b) is a figure which shows the moving amount | distance of a movable iron core. It is sectional drawing which shows the full injection | throwing-in state of an electromagnetic contactor. It is a figure which shows the incomplete open state of an electromagnetic contactor. It is a flowchart which shows an example of the movable state determination processing procedure of a movable state determination apparatus. It is sectional drawing of the release state of the electromagnetic switch which shows the 2nd Embodiment of this invention. It is a time chart at the time of the release start of 2nd Embodiment, (a) is a figure which shows the detection voltage change of a magnetic sensor, (b) is a figure which shows the moving amount | distance of a movable iron core. It is sectional drawing which shows the complete injection | throwing-in state in 2nd Embodiment. It is sectional drawing which shows the incomplete open state in 2nd Embodiment. It is a flowchart which shows an example of the movable state determination processing procedure of the movable state determination apparatus in 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing a first embodiment when the present invention is applied to an electromagnetic contactor as an electromagnetic switch. In FIG. 1, in the electromagnetic contactor, a contact device 2 having a contact mechanism and an electromagnet unit 3 as an electromagnet device for driving the contact device 2 are arranged in series with the electromagnet unit 3 on the lower side.
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. 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 brazing or the like.

Further, the contact device 2 is disposed so as to be opposed to the movable contact 11 so that the movable contact 11 can contact and separate from the lower end surfaces 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 iron core 25 of the electromagnet unit 3 described later and is driven in the vertical direction.
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 iron core 25 is slidably mounted on the inner peripheral surface of the cylindrical portion 21b. A cap 26 is provided. A fixed iron core 27 is disposed on the upper end side of the cap 26 so as to face the movable iron core 25.

A connecting shaft 28 is fitted to the center of the movable iron core 25, and the head of the connecting shaft 28 extends upward through a central opening of the fixed iron core 27 and a through hole 29 formed in the upper magnetic yoke 22. It is connected to the child holder 13.
A spring insertion hole 30 is formed around the connecting shaft 28 of the movable iron core 25, and a return spring 31 that biases the movable iron core downward is mounted between the spring insertion hole 30 and the fixed iron core 27.
Then, hydrogen gas, nitrogen gas, a mixed gas of hydrogen and nitrogen, air, SF in a sealed space constituted by the contact housing case 4 constituted by the flange 4a and the joining member 4b, the upper magnetic yoke 22 and the cap 26 An arc extinguishing gas such as ₆ is enclosed.

A permanent magnet 32 is embedded in the bottom of the movable iron core 25, and a magnetic sensor 33 is disposed at a position facing the permanent magnet 32 through the bottom of the cap 26. Changes in the magnetic flux of these permanent magnets 32 are detected, and a voltage signal representing the amount of change in the magnetic flux is output.
Here, the change of the voltage signal Vs output from the magnetic sensor 33 is as shown in FIG.
That is, the exciting coil 23 of the electromagnet unit 3 is energized, and the movable contact 11 is attracted to the fixed iron 27 against the return spring 31 as shown in FIG. The contact spring 14 is in contact with a predetermined contact pressure (closed state). When the energization of the exciting coil 23 of the electromagnet unit 3 is interrupted from this input state and the state shifts to the release state shown in FIG. 1, the voltage change of the magnetic sensor 33 is as shown in FIG.

That is, for example, when the movable contact 11 is in contact with the fixed contacts 6a and 6b with a predetermined contact pressure of the contact spring 14, the moving amount of the movable iron core 25 is as shown in FIG. The upper end of the movable iron core 25 is in contact with the lower end of the fixed iron core 27 and the moving amount is the largest.
In this state, for example, when the energization of the exciting coil 23 of the electromagnet unit 3 is cut off at the time t1 and the magnetic flux generated in the exciting coil 23 is reduced, the attractive force of the fixed iron core 27 is reduced accordingly, so The iron core 25 moves downward by the elastic force of the return spring 31. At this time, when there is no welding between the contact portion of the movable contact 11 and the contact portion between the fixed contacts 6a and 6b, the bottom surface of the movable iron core 25 is capped as shown by the solid line in FIG. It descends to a position where it contacts the bottom surface of the cap 26, and stabilizes in a state where it contacts the bottom surface of the cap 26.

However, if welding occurs between the movable contact 11 and at least one of the fixed contacts 6a and 6b in the input state, the movable contact 11 is not separated from the fixed contact 6a or 6b. For this reason, as shown by the broken line in FIG. 2B, the movable iron core 25 is lowered to a position where the compressed state of the contact spring 14 is released, but further lowering is prevented.
At this time, the detection voltage Vs corresponding to the change in magnetic flux detected by the magnetic sensor 33 causes welding between the movable contact 11 and the fixed contacts 6a and 6b, as shown in FIG. If not, it was confirmed that the decreasing trend continued from the release start time t1 as shown by the solid line in FIG. 2 (a), rapidly increased by a predetermined amount at time t3, and then stabilized.

On the other hand, when welding has occurred between the movable contact 11 and at least one of the fixed contacts 6a and 6b, as shown in the broken line in FIG. It was confirmed that the detection voltage of the magnetic sensor 33 increased by a predetermined amount at time t2 earlier than t3, and then stabilized.
Therefore, by measuring the time from the release start time t1 to the time when the detected voltage of the magnetic sensor 33 is determined to be increased, the normal state threshold is set between the time t2 and the time t3. It is possible to determine whether or not is normal.
For this reason, as shown in FIG. 1, the voltage signal output from the magnetic sensor 33 is input into the movable state determination apparatus 34 as a movable state determination part. The movable state determination device 34 includes an arithmetic processing circuit such as a microcomputer, and executes an operation determination process shown in FIG.

In this movable state determination process, the exciting coil 23 of the electromagnet unit 3 is energized to release the exciting coil 23 in a non-excited state in a state where the movable contactor 11 is in contact with the fixed contacts 6a and 6b. When shifting to the state, it is executed as a timer interrupt process at predetermined time intervals (for example, 10 msec).
In this movable state determination process, first, the current output voltage V (n) of the magnetic sensor 33 is read in step S1, and then the process proceeds to step S2 where the previous output voltage stored in a memory unit such as a RAM is stored. After reading V (n-1) and subtracting the current output voltage V (n) from the previous output voltage V (n-1) to calculate the voltage change amount ΔV, the process proceeds to step S3.
In step S3, it is determined whether or not the voltage change amount ΔV is positive. If ΔV> 0, it is determined that the output voltage of the magnetic sensor 33 is decreasing, and the process proceeds to step S4. After incrementing the variable N representing the travel time of “1” by “1”, the timer interrupt process is terminated and the process returns to the predetermined main program.

On the other hand, if the determination result in step S3 is ΔV ≦ 0, it is determined that the output voltage Vs of the magnetic sensor 33 has not changed or has increased, and the process proceeds to step S5, where the previous voltage change amount ΔV is positive. It is then determined whether or not the decreasing trend is continued.
If the result of this determination is that the previous voltage change amount ΔV is ΔV ≦ 0, it is determined that the movable core 25 has not risen, the process proceeds to step S6, the variable N is cleared to “0”, and then the timer interrupt occurs. The process ends and the process returns to a predetermined main program.

However, when the determination result in step S5 is ΔV <0, it is determined that the voltage decreasing tendency continues, and the process proceeds to step S7, where it is determined whether the minimum value of the detected voltage is detected, and the minimum value is determined. If the timer is not detected, the timer interrupt process is terminated as it is, and the process returns to the predetermined main program. If the minimum value is detected, the process proceeds to step S8.
In this step S8, the variable N is read and it is determined whether or not the variable N is equal to or greater than a preset normal determination threshold Nth. If N ≧ Nth, the moving amount of the movable iron core 25 is normal. Determination is made and the process proceeds to step S9.

In step S9, a normal detection signal Sn indicating that the moving amount of the movable iron core 25 is normal is output to an external monitoring unit, and then the process proceeds to step S11.
On the other hand, if the determination result in step S8 is N <Nth, it is determined that the movable iron core 25 is in an incompletely open state, and the process proceeds to step S10, where the abnormality detection signal San is externally monitored. The process proceeds to step S11.
In step S11, the variable N is cleared to "0", the timer interrupt process is terminated, and the process returns to a predetermined main program.

Next, the operation of the first embodiment will be described.
Now, it is assumed that the fixed contact 6a is connected to a DC power source (not shown), the fixed contact 6b is connected to a load, and the exciting coil 23 of the electromagnet unit 3 is in a non-excited state.
In this state, a magnetic path passing through the fixed iron core 27 is not formed, so that no attractive force is generated in the fixed iron core 27, the movable iron core 25 is urged downward by the return spring 31, and the bottom of the movable iron core 25 is capped. 26 is in contact with the bottom.
In this state, as shown in FIG. 1, the movable contact 11 is separated by a predetermined gap downward from the lower surfaces of the fixed contacts 6a and 6b, and the contact device 2 is in a released state.

In this released state, since the movable iron core 25 is closest to the magnetic sensor 33, a large leakage magnetic flux from the permanent magnet 32 is supplied to the magnetic sensor 33. Therefore, a large level voltage signal is output from the magnetic sensor 33 as shown in FIG.
However, in the movable state determination device 34, in the released state, the above-described movable state determination process of FIG. 5 is not executed, and the movable state determination process is stopped.
When the exciting coil 23 of the electromagnet unit 3 is energized from this released state, the bottom plate portion of the magnetic yoke 21 is thereby passed from the fixed iron core 27 to the movable iron core 25 through the cylindrical portion 21b as shown in FIGS. A magnetic path returning to the fixed core 27 through the upper magnetic yoke 22 through the side plate portion 21a is formed. Thereby, the movable iron core 25 is attracted to the fixed iron core 27 against the return spring 31 and the movable iron core 25 is raised.

As a result, the movable contact 11 comes into contact with the fixed contacts 6 a and 6 b, and the movable iron core 25 rises while compressing the contact spring 14, thereby contacting the upper end of the movable iron core 25 or the lower end of the fixed iron core 27. Then, the raising of the movable iron core 25 is stopped and the input state is entered.
In this input state, when the energization of the exciting coil 23 of the electromagnet unit 3 is cut off and shifted to the released state at the time t1 in FIGS. The illustrated movable state determination process is started.
At this time, the movable iron core 25 starts to descend by the elastic force of the return spring 31 as the suction force of the fixed iron core 27 decreases. In this way, the movable iron core 25 starts to descend and the magnetic flux generated by the exciting coil 23 decreases, so that the leakage magnetic flux reaching the magnetic sensor 33 decreases, and the detected voltage of the magnetic sensor 33 corresponding to this decreases as shown in FIG. Decrease gradually as shown in

For this reason, since the movable state determination device 34 performs the movable state determination process of FIG. 5, the voltage change amount ΔV calculated in step S2 becomes negative indicating a decrease, and the process proceeds from step S3 to step S4. The variable N is incremented by “1”.
Thereafter, since the lowering of the movable iron core 25 is continued, the output voltage of the magnetic sensor 33 continues to decrease relatively slowly as shown in FIG. Therefore, the variable N is incremented by “1” every time the timer interrupt process is executed.
Thereafter, when the contact pressure of the contact spring 14 is released at the time t2 and there is no welding between the movable contact 11 and the fixed contacts 6a and 6b, the movable contact 11 starts to descend, and moves in response to this. The iron core 25 also continues to descend. Therefore, the variable N is continuously incremented in the movable state determination process of FIG.

During this time, the detection voltage of the magnetic sensor 33 also continues to decrease, and when the bottom surface of the movable iron core 25 comes into contact with the bottom surface of the cap 26 at time t3, the descent of the movable iron core 25 is stopped. When the lowering of the movable iron core 25 is stopped in this way, the detection voltage detected by the magnetic sensor 33 increases rapidly by a predetermined amount and then becomes stable.
In this state, the variable N exceeds the normal determination threshold value Nth.
As described above, when the detection voltage Vs of the magnetic sensor 33 is reversed to an increasing tendency, the process shifts from step S3 to step S5 in the movable state determination process of FIG. 5, and since ΔV> 0 last time, the process shifts to step S7. Since the minimum value is detected, the process proceeds to step S8.
In step S8, the variable N is read. Since the variable N is equal to or greater than the normal determination threshold value Nth, the process proceeds to step S9, and after the normal detection signal Sn is output to the monitoring unit, the variable N is set to “0”. To clear the timer interrupt processing and return to a predetermined main program.

However, when the movable contact 11 is welded to at least one of the fixed contacts 6a and 6b, as described above, when the state shifts to the release state at the time t1 in FIGS. 2 (a) and (b), At the time t2 when the contact pressure of the contact spring 14 is released, the lowering of the movable iron core 25 is stopped.
For this reason, in the magnetic sensor 33, as shown by the broken line in FIG. 2A, the detection voltage suddenly increases to a predetermined value at time t2. Therefore, in the movable state determination process of FIG. 5, the process proceeds from step S3 to steps S5 and S7 to step S8, and the variable N becomes smaller than the normal determination threshold value Nth. Therefore, the process proceeds to step S10 and the abnormality detection signal San. Is output to the monitoring unit. Then, in the determination process of whether it is in the movable state, the process proceeds from step S10 to step S11, the variable N is cleared to “0”, the timer interrupt process is terminated, and the process returns to the predetermined main program.

As described above, when the transition is made from the input state to the release state, the movable state determination device 34 performs the movable state determination process shown in FIG. 5, so that the movable contact 11 is based on the detection voltage Vs of the magnetic sensor 33. Between the movable contact 11 and the fixed contacts 6a and 6b, or at least one of the fixed contacts 6a and 6b is in an incompletely opened state. Can be accurately determined.
The operating state of the movable iron core 25 is magnetically detected by the permanent magnet 32 and the magnetic sensor 33 provided on the movable iron core 25 on the outside of the sealed container composed of the contact housing case 4, the upper magnetic yoke 22 and the cap 26. Thus, unlike the conventional example described above, there is no need to arrange the detection unit in the sealed container, so that it is not necessary to perform a sealing process, and the operating state of the movable iron core 25 can be easily detected.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, the operating state of the movable iron core 25 is detected from the magnetic flux in the magnetic path of the electromagnet unit 3 in place of the detection unit using the permanent magnet and the magnetic sensor.
That is, in the second embodiment, as shown in FIG. 6, the search coils 40a and 40b for detecting the magnetic flux flowing through the magnetic yoke 21 forming the magnetic path of the electromagnet unit 3 as an induced voltage are arranged. Is.

Thus, by mounting the search coils 40a and 40b on the left and right side plates of the magnetic yoke 21, the voltages induced in the search coils 40a and 40b are as shown in FIG. That is, as in the first embodiment described above, the induced voltage induced in the search coils 40a and 40b when the input state is changed to the released state is shown in FIG. 8 as shown in FIG. In the fully charged state where there is no welding between the movable contact 11 and the fixed contacts 6a and 6b, the peak voltage Vp1 when returning to the release state is any of the movable contact 11 and the fixed contacts 6a and 6b shown in FIG. It has been confirmed that the peak voltage Vp2 is higher than the peak voltage Vp2 in the case of the incompletely open state in which welding occurs between the two and the peak voltage Vp1 is later than the peak voltage V2. .

For this reason, it is determined whether or not the peak voltage value of the induced voltages of the search coils 40a and 40b is abnormal for the normal threshold value Vpn, or the time from the release start state to the detection of the peak voltage is equal to or greater than the normal determination threshold value Tth. By determining whether or not, the movable state of the movable iron core 25, that is, the movable state of the movable contactor 11 can be determined.
For this reason, in the present embodiment, the induced voltage Vi of the search coils 40a and 40b is input to the movable state determining device 34, and the movable state determining process is performed as shown in FIG. In the movable state determination process of step S3, the process of step S3 is changed to step S21 for determining whether or not the induced voltage Vi of the search coils 40a and 40b has reached the peak voltage Vip. When the voltage Vip has not been reached, the routine proceeds to step S4, where the variable N is incremented by “1”, and when the peak voltage Vip has been reached, the routine proceeds directly to step S8.

Also in the second embodiment, when the movable contact 11 is in contact with the stationary contacts 6a and 6b and is shifted from the released state to the released state, the movable state determination device 34 is in the activated state, and FIG. The movable state determination process shown is executed.
Therefore, when the movable contact 11 is not welded to the fixed contacts 6a and 6b, the induced voltage Vi of the search coils 40a and 40b from the start of release is. When the time to reach the peak value Vip is delayed and the variable N becomes larger than the normal determination threshold value Nth, it is determined as a normal operation state, and the normal detection signal Sn is output to the monitoring unit.

On the other hand, in the incompletely open state where the movable contact 11 is welded to at least one of the fixed contacts 6a and 6b, the time until the induced voltage Vi of the search coils 40a and 40b reaches the peak voltage Vip is short. The variable N becomes smaller than the normal determination threshold value Nth, and it is determined that the operation is abnormal, and the abnormality detection signal San is output to the monitoring unit.
As described above, also in the second embodiment of the present application, the movable state of the movable iron core 25 can be accurately determined by detecting the magnetic flux change through the magnetic yoke 21 as the voltage change by the search coils 40a and 40b.

In the second embodiment, similarly to the first embodiment described above, the movable state of the movable iron core 25, that is, the movable contact 11, can be easily and accurately determined by a magnetic change outside the sealed container.
In the second embodiment, the case where the operation state is determined by measuring the time from the release start time t1 until reaching the peak voltage Vip has been described. However, the present invention is not limited to this. The presence or absence of welding between the movable contact 11 and the fixed contacts 6a and 6b may be determined based on whether or not the peak voltage Vip detected at 40a and 40b is greater than the normal threshold voltage Vipth.

In the second embodiment, the case where the search coils 40a and 40b are wound around the entire circumference of the magnetic yoke 21 has been described. However, the present invention is not limited to this, and a cutout portion is provided in the magnetic yoke 21. A search coil may be wound around the notch.
In the first and second embodiments, the case where the normal detection signal Sn and the abnormality detection signal San output from the movable state determination device 34 are sent to the monitoring unit has been described. However, the present invention is not limited to this. In addition, the abnormality detection signal San may be output to the drive circuit of the light emitting diode to notify the abnormal state by light, and may be supplied to another display device.

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 2 ... Contact apparatus, 3 ... Electromagnet unit, 4 ... Contact storage case, 4a ... Rod-like body, 4b ... Joining member, 4c ... Metal cylinder, 6a, 6b ... Fixed contact, 11 ... Movable contact, 13 ... Contact Child holder, 14 ... contact spring, 21 ... magnetic yoke, 22 ... upper magnetic yoke, 23 ... excitation coil, 24 ... coil holder, 25 ... movable iron core, 26 ... cap, 27 ... fixed iron core, 28 ... connection shaft, 31 ... Return spring, 32 ... permanent magnet, 33 ... magnetic sensor, 34 ... movable state determination device, 40a, 40b ... search coil

Claims (3)

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 movable state detector that detects the movable state of the movable contact as a magnetic change;
An electromagnetic switch comprising: a movable state determining unit that determines whether or not the movable state of the movable contact is normal based on a detection result of the movable state detecting means. The said movable state detection part is comprised by the permanent magnet arrange | positioned at the movable iron core which moves the said movable contact, and the magnetic sensor which detects the change of the magnetic flux of this permanent magnet, The Claim 1 characterized by the above-mentioned. The electromagnetic switch described. The electromagnetic switch according to claim 1, wherein the movable state detection unit is configured by a search coil that detects an induced voltage due to a magnetic flux of a magnetic yoke of the electromagnet unit.

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