A rare earth permanent magnet synchronous switch with capacitive energy storage

Abstract

The present invention relates to a rare earth permanent magnet synchronous switch with capacitive energy storage, which includes a main contact (also known as a main contactor) and an auxiliary contact (also known as an auxiliary contactor) installed inside the arc suppression chamber, an operating coil (collectively referred to as the closing coil and the opening coil) installed on the static contact, a moving contact assembly with permanent magnets at both ends of the conductor, a measurement and control circuit, etc. The main contact is used to connect / break the working current and withstand short-term arcing, the auxiliary contact provides the switch state output, the moving contact with permanent magnets is used to connect / break the working current, and the measurement and control circuit discharges pulses to the operating coil installed on the static contact, driving the permanent magnet through the magnetic field to drive the moving contact and the conductor to instantaneously change positions, thereby switching the switch state. In the case of ordinary lower operating frequencies or smaller currents, it can significantly reduce the failure rate of switchgear and greatly extend its service life.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical switches, and particularly to a rare earth permanent magnet synchronous switch with capacitive energy storage. Background Art

[0002] As a device for cutting off a circuit, a switch is widely used in power systems.

[0003] Both switches and relays (contactors) control high voltage and large current through low voltage and small current. Generally speaking, switches control higher voltages and larger currents than relays. There is also a generally accepted difference, that is, the control coil of a switch is only energized for a short time when the closing / opening action occurs, while the control coil of a relay (contactor) is energized for a long time during operation.

[0004] Switching devices applied to high-voltage and large-current occasions are not suitable for frequent operations. Because when high voltage and large current are interrupted, an arc is inevitably generated at the break. Generally, the shorter the arc combustion time, the better. This requires that both the opening and closing actions between the moving and static contacts must be completed at an extremely fast speed within a very short time (generally within 60 - 110 ms). In order to ensure the opening and closing speed of the switch, a energy storage motor, an energy storage spring, and a complex transmission mechanism are designed on traditional switching devices. Its working mode is generally divided into three stages: In the first stage, the energy storage motor rotates, and the energy storage spring is stretched through a reduction mechanism to store sufficient elastic potential energy; in the second stage, a closing coil is used to push the iron core, and a part of the above elastic potential energy is released to the moving contact and its connected mechanism, so that the moving contact quickly moves to the closing position and remains in the closing position; in the third stage, a tripping coil is used to push the iron core, and the remaining elastic potential energy is released to the moving contact and its connected mechanism, so that the moving contact quickly moves to the opening position. After the opening is completed, the next energy storage cycle begins.

[0005] Because during the closing process, in addition to doing work on the moving contact (and its connected mechanism), the closing spring also needs to stretch the opening spring to do work at the same time, while during the opening process, the opening spring only does work on the moving contact and its connected mechanism. Therefore, the closing time and the opening time are not equal. Generally, the closing time (60 - 110 ms) is significantly longer than the opening time (30 - 50 ms).

[0006] The shorter opening time indicates that the opening speed is faster than the closing speed. As a result, after the opening process is completed, the mechanical inertia carried by the moving parts is very large, and a special buffer mechanism needs to be designed to absorb this part of kinetic energy. In maintenance practice, the buffer mechanism of imported switches needs to be maintained regularly and spare parts need to be replaced, increasing the cost; while the buffer mechanism of domestic switches is damaged frequently.

[0007] The existence of these energy storage motors, energy storage springs, and relatively complex transmission mechanisms, with their mass inertia and mechanical wear, determines that switches applied to high-voltage and large-current scenarios cannot continuously operate in a state of frequent opening and closing. Their electrical life is claimed to be tens of thousands of times, but the actual mechanical life is generally only a few thousand times. Because there are many fault points, the maintenance life is even shorter.

[0008] In scenarios where frequent switching operations of high voltage or large current are required, a switch device with a simple and reliable structure that can adapt to relatively frequent continuous opening and closing operations is needed.

[0009] In the field of power technology, a switch that can perform closing and opening at the zero-crossing moment of alternating current is called a synchronous switch. The prominent advantage of a synchronous switch is that, since the opening and closing operations are performed at the moment when the circuit current is close to zero, the arc is minimized, and the possibility of contact erosion is minimized, which can greatly extend the service life of the switch device.

[0010] Therefore, how to design a synchronous switch to ensure that in ordinary low operating frequency or small current scenarios, the failure rate of the switch device can be significantly reduced and its service life can be greatly extended is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0011] The present invention provides a rare earth permanent magnet synchronous switch with capacitor energy storage to solve the technical problems in the prior art that in ordinary low operating frequency or small current scenarios, the failure rate of the switch device is relatively high and the service life is low.

[0012] The synchronous switch includes:

[0013] A measurement and control circuit for providing pulsed current to the arc suppression chamber;

[0014] An arc suppression chamber, including a moving contact assembly, a static contact assembly, and an arc suppression chamber housing, for adjusting the connection relationship between the moving contact assembly and the static contact assembly through the pulsed current of the measurement and control circuit, and adjusting the opening state of the synchronous switch;

[0015] Among them, the moving contact assembly includes a first moving contact, a second moving contact, and a moving contact assembly;

[0016] The static contact assembly includes a first static contact, a second static contact, a third static contact, and a fourth static contact;

[0017] The opening state includes a closing state or an opening state.

[0018] In some embodiments of the present application, the first moving contact and the second moving contact are provided with permanent magnets.

[0019] In some embodiments of the present application, electromagnets are installed on the first static contact, the second static contact, the third static contact, and the fourth static contact. The electromagnet includes an electromagnet coil and an iron core.

[0020] In some embodiments of the present application, the measurement control circuit includes a DC constant current power supply, an energy storage capacitor, and a single-pole double-throw switch.

[0021] In some embodiments of the present application, the common connection point of the anode of the DC constant current power supply and the first end of the energy storage capacitor is connected to the first end of the single-pole double-throw switch, and the common connection point of the cathode of the DC constant current power supply and the second end of the energy storage capacitor is connected to the second end of the single-pole double-throw switch. The third end and the fourth end of the single-pole double-throw switch are respectively connected to the electromagnet coils of the first static contact, the second static contact, the third static contact, and the fourth static contact.

[0022] In some embodiments of the present application,

[0023] When the blade of the single-pole double-throw switch is in the middle, the electrical connection relationship between the DC constant current power supply and the electromagnet coils of the first static contact, the second static contact, the third static contact, and the fourth static contact is disconnected, and the DC constant current power supply charges the energy storage capacitor.

[0024] When the single-pole double-throw switch is closed to the left, the energy storage capacitor provides pulsed current to the electromagnet coils of the first static contact, the second static contact, the third static contact, and the fourth static contact. Through the electromagnetic force between the electromagnet and the permanent magnet, it controls the connection of the first static contact, the first moving contact, the moving contact assembly, the second moving contact, and the second static contact, and controls the opening state of the synchronous switch to the closed state.

[0025] When the single-pole double-throw switch is closed to the right, the energy storage capacitor provides pulsed current to the electromagnet coils of the first static contact, the second static contact, the third static contact, and the fourth static contact. Through the electromagnetic force between the electromagnet and the permanent magnet, it controls the connection of the third static contact, the first moving contact, the moving contact assembly, the second moving contact, and the fourth static contact, and controls the opening state of the synchronous switch to the open state.

[0026] In some embodiments of the present application, buffer pads are provided at the bottoms of the first static contact, the second static contact, the third static contact, and the fourth static contact.

[0027] In some embodiments of the present application, the moving contact assembly, the static contact assembly and the electromagnet are sealed in the arc suppression chamber by an insulating material.

[0028] By applying the above technical solutions, the synchronous switch includes: a measurement and control circuit for providing a pulsed current to the arc suppression chamber; the arc suppression chamber includes a moving contact assembly, a static contact assembly, and an arc suppression chamber housing, and is used to adjust the connection relationship between the moving contact assembly and the static contact assembly through the pulsed current of the measurement and control circuit, and adjust the opening state of the synchronous switch. Compared with the prior art, it has the following advantages and beneficial effects:

[0029] 1. Greatly simplifies the mechanical structure of the switch, improves reliability, and at the same time can reduce the overall external dimensions of the switch and save installation space.

[0030] 2. The opening and closing processes are exactly the same, and the coil structure models, sizes, etc. used are also exactly the same, which simplifies spare parts.

[0031] 3. The closing and opening times are exactly equal, which greatly reduces the control difficulty of the synchronous switch.

[0032] 4. Since the capacitor energy storage method is adopted, compared with the energy storage method of the motor + spring mechanism, the required energy storage time is greatly shortened, and production and maintenance are more convenient.

[0033] 5. During the opening and closing operations of the switch, the volume of the moving parts that need to be driven is greatly reduced, and the inertial mass is greatly reduced. Therefore, the energy consumption and wear of the switch during opening and closing operations are very small, and the service life is longer.

[0034] 6. The switch operates more sensitively, and the opening and closing times are stable, meeting the requirements for the accuracy of the repeated action time of synchronous switching.

[0035] 7. The structural strength of the buffer mechanism and the base number for absorbing residual energy are greatly reduced. The switch noise is also greatly reduced.

[0036] 8. The double break formed by the structural design naturally ensures a greater current interruption capacity and a greater insulation margin for the break. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 Shows the schematic diagram of a rare earth permanent magnet synchronous switch with capacitor energy storage proposed in the embodiments of the present application;

[0039] Figure 2 Shows a partial enlarged view of the contact state between the moving contact and the static contact of a rare earth permanent magnet synchronous switch with capacitive energy storage proposed in an embodiment of the present application;

[0040] Figure 3 Shows the circuit schematic diagram of the measurement and control circuit in an embodiment of the present application;

[0041] Figure 4 Shows the schematic diagram of a rare earth permanent magnet synchronous switch with capacitive energy storage proposed in another embodiment of the present application;

[0042] Figure 5 Shows the schematic diagram of the zero-crossing moment of three-phase alternating current in an embodiment of the present application;

[0043] Figure 6 Shows the schematic diagram of the synchronous drive measurement and control logic in an embodiment of the present application.

[0044] Reference numerals: 1, moving contact rotating shaft; 2, arc suppression chamber housing; 31, first static contact; 32, second static contact; 33, third static contact; 34, fourth static contact; 4, moving contact assembly; 41, first moving contact; 4, moving contact assembly; 42, second moving contact; 10, buffer pad; 11, permanent magnet; 12, electromagnet coil; 13, iron core; 5, DC constant current power supply; 6, energy storage capacitor; 7, single-pole double-throw switch; 100, main control instruction; 200, high-speed subtraction timer; 300, register; 400, power-off storage register; 500, subtractor + delay counter; 600, delay counter; 700, delay counter; 801, A-phase drive circuit; 802, C-phase drive circuit; 803, B-phase drive circuit. Detailed implementation manners

[0045] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0046] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0047] Such as Figure 1As shown, it is a schematic diagram of a rare earth permanent magnet synchronous switch with capacitive energy storage. The first moving contact 41, the second moving contact 42, and the conductor are rigidly connected into an integral component: the moving contact assembly 4, which can rotate around the shaft 1.

[0048] Figure 1 The left side shows the closing state of the switch. The moving contact assembly 4 is in the first stable position: electrically connecting the first static contact 31 and the second static contact 32. The first static contact 31, the first moving contact 41, the moving contact assembly 4, the second moving contact 42, and the second static contact 32 together form a current flow path. At this time, the main circuit is in the closing state.

[0049] Figure 1 The right side shows the opening state of the switch. At this time, the moving contact assembly 4 rotates around the shaft 1 to another stable position, electrically connecting the third static contact 33 and the fourth static contact 34. The fourth static contact 34, the first moving contact 41, the moving contact assembly 4, the second moving contact 42, and the third static contact 33 form a current flow path, providing the output of the switch opening state. At this time, the first static contact 31 and the second static contact 32 are in the opening state.

[0050] The rare earth permanent magnet synchronous switch with capacitive energy storage can be maintained in any one of the two stable positions for a long time or switched back and forth between the two stable positions. The switching action is achieved by the interaction between the magnetic field generated by the excitation of the electromagnet on the static contact and the permanent magnets on the first moving contact 41 and the second moving contact 42.

[0051] As Figure 2 shown (taking only one pair of moving and static contacts as an example, and the principle of the other pair is the same), 11 is a permanent magnet (the shaded part), made of rare earth permanent magnet neodymium iron boron material, and its magnetic field direction is fixed and unchanged. The electromagnet includes an electromagnet coil 12 and an iron core 13. The magnetic field direction of the electromagnet is jointly determined by the coil winding direction and the excitation current direction, and can be changed.

[0052] On the premise that the coil winding direction has been determined, a positive current is simultaneously passed through the electromagnet coil 12 in contact with the first moving contact 41 and the second moving contact 42, so that the magnetic field direction generated by it is the same as the magnetic field direction of the permanent magnet. Then, the iron core 13 of the electromagnet and the permanent magnets of the first moving contact 41 and the second moving contact 42 attract each other, and the switch state will remain unchanged.

[0053] In fact, due to the magnetization effect of the iron core of the electromagnet, even if the positive current disappears in a short time, the iron core 13 and the permanent magnets of the first moving contact 41 and the second moving contact 42 can still maintain mutual attraction, and the switch state can still remain unchanged.

[0054] When it is necessary to change the switch state, that is, to trip from the closed state or to close from the open state, a reverse current pulse is passed through the electromagnet coil 12 in contact with the first moving contact 41 and the second moving contact 42. The magnetic field direction of the electromagnet changes instantaneously, and the iron core 13 of the electromagnet repels the permanent magnets of the first moving contact 41 and the second moving contact 42, pushing the first moving contact 41, the moving contact assembly 4, and the second moving contact 42 to rotate around the rotating shaft 1 as a whole to reach another stable position.

[0055] To prevent the first stationary contact 31, the second stationary contact 32, the third stationary contact 33, and the fourth stationary contact 34 from hitting the first moving contact 41 and the second moving contact 42 hard, resulting in an unstable state of the so-called "bouncing" of the switch, buffer pads 10 are provided at the bottoms of all stationary contacts.

[0056] The first moving contact 41, the moving contact assembly 4, the second moving contact 42, the first stationary contact 31, the second stationary contact 32, the third stationary contact 33, the fourth stationary contact 34, the electromagnet coil 12, and the iron core 13 are all sealed inside the arc suppression chamber 2 made of insulating material.

[0057] As Figure 3 shown, it is the schematic diagram of the measurement and control circuit of the rare earth permanent magnet synchronous switch with capacitor energy storage.

[0058] 5 is a DC constant current power supply. 6 is an energy storage capacitor. The energy storage capacitor is connected in parallel with the DC constant current power supply. The function of the energy storage capacitor is to provide a large pulse current to the electromagnet coil at the moment when the switch operates, accelerating the switching movement of the first moving contact 41 and the second moving contact 42, so it is also called an accelerating capacitor. After the switching action is completed, because the DC resistance of the electromagnet coil is small, the DC constant current power supply will work in an approximate short-circuit (constant current) state for a very short time (1 - 2 s).

[0059] 7 is a single-pole double-throw switch. When its knife switch is in the middle state, the electrical connection between the DC constant current power supply and the electromagnet coil is disconnected. At this time, the DC constant current power supply charges the energy storage capacitor. Assuming that when the single-pole double-throw switch closes to the left, the excitation direction of the DC constant current power supply for the electromagnet coil corresponds to the closing action; then when the single-pole double-throw switch closes to the right, the positive and negative poles applied to the electromagnet coil by the DC constant current power supply will be reversed, and the excitation direction of the electromagnet coil corresponds to the opening action.

[0060] As mentioned above, in addition to the direction of the excitation current, the winding direction of the electromagnet coil of the first stationary contact 31, the second stationary contact 32, the third stationary contact 33, and the fourth stationary contact 34 also determines the magnetic polarity. Here, it is particularly emphasized that the principle of the magnetic polarity matching of the moving and stationary contacts: the side where the moving contact leaves is of the same polarity, and the side where the moving contact arrives is of the opposite polarity. In this way, when the switch (circuit breaker) makes a switching action, the magnetic force directions acting on both sides of the moving contact are the same.

[0061] As described above, the single-pole double-throw switch does not need to be always closed to the left or opened to the right all the time. Just by a momentary operation, the purpose of switching the switch state can be achieved.

[0062] For the sake of visualization, the single-pole double-throw switch is taken as an example to illustrate its working principle. In actual implementation, in order to meet the requirements of automatic control, electronic components such as GTO (gate turn-off thyristor) will be used to achieve the same function as the above single-pole double-throw switch. Any professional in the field of power electronics should be able to easily understand and implement it, and thus it will not be elaborated here.

[0063] As Figure 4 shown, it is the schematic diagram of a rare earth permanent magnet synchronous switch with capacitor energy storage proposed in another embodiment of the present application.

[0064] Compared with Figure 1 the corresponding embodiment, the moving contact rotating shaft 1 is cancelled. When making the state switching action, the moving contact changes from a rotational motion to a translational motion. Depending on the mutual attraction and natural positioning between the iron core 13 of the electromagnet and the permanent magnet 11 on the moving contact, the switch action will be more agile.

[0065] For the two embodiments of the rare earth permanent magnet synchronous switch with capacitor energy storage, in the open state, a series break can be naturally formed, and it has good arc interruption ability and insulation margin.

[0066] Next, in conjunction with Figure 5 and Figure 6 it is described how the switch achieves the principle of synchronous opening and closing.

[0067] As Figure 5 shown, it is the schematic diagram of all three-phase alternating current zero-crossing moments. Taking the power frequency (50Hz) alternating current as an example, within 1000ms (i.e., 1 second), there are 50 cycles, so the time length of each cycle is 20ms. As Figure 5 shown, within each 20ms time interval, the three-phase alternating current has 6 zero-crossings in total. They are in sequence: the A phase changes from negative to positive, the C phase changes from positive to negative, the B phase changes from negative to positive, the A phase changes from positive to negative, the C phase changes from negative to positive, and the B phase changes from positive to negative. The time interval between two adjacent zero-crossings is t0 = 20 / 6 (ms)

[0068] As Figure 6 shown, it is the schematic diagram of the synchronous drive measurement and control logic.

[0069] First of all, it is necessary to regularly calibrate the inherent opening and closing times of the rare earth permanent magnet synchronous switch with capacitor energy storage. The calibration result t2 is manually written into the special register 400 for power-off storage.

[0070] For the sake of simplicity of description, it is assumed that the reset signal of the synchronous countdown timer 200 is taken from phase A. Each time the current of phase A passes through zero, the synchronous countdown timer 200 is reset, and then the timing starts again from t0 = 20 / 6.

[0071] When the main control instruction 100 (closing or opening) is issued, the timing result t1 of the synchronous countdown timer 200 is written into the register 300.

[0072] The subtractor 500 is used to subtract the timing value t1 (remaining time of countdown) in the register 300 from the calibrated inherent closing and opening time value t2 in the register 400 to obtain the closing and opening time of phase A, Ta = t1 - t2. That is, after Ta (ms) is extended, the drive circuit 801 is started to pulse-discharge the electromagnet coil to perform the closing and opening actions. Similarly, the delay counter 600 will issue a drive instruction through 802 after Tc = Ta + 20 / 6 (ms), and the delay counter 700 will issue a drive instruction through 803 after Tb = Tc + 20 / 6 (ms). The pulse currents sequentially issued by 801, 802, and 803 at intervals of 20 / 6 (ms) will sequentially switch the states of the A, C, and B phase circuit breakers (from the open state to the closed state, or from the closed state to the open state). Obviously, this electrical process only lasts for 20 / 6 * 2 = 20 / 3 (ms).

[0073] To prevent the problem that the remaining time t1 of the countdown is less than t2 and a negative value appears when calculating Ta = t1 - t2, the initial value t0 of the synchronous countdown timer 200 can be set to N * 20 / 6, (N is a positive integer greater than 1), to ensure that Ta is greater than zero in any case.

[0074] Generally speaking, a high-speed timing pulse with a width of 10 microseconds (i.e., 100Khz) that is easy to implement in engineering can meet the required control accuracy.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A rare earth permanent magnet synchronous switch with capacitive energy storage, characterized in that The synchronous switch includes: A measurement control circuit for providing a pulsed current to the arc suppression chamber; The arc suppression chamber, including a moving contact assembly, a static contact assembly, and an arc suppression chamber housing, for adjusting the connection relationship between the moving contact assembly and the static contact assembly through the pulsed current of the measurement control circuit, and adjusting the opening state of the synchronous switch; Wherein, the moving contact assembly includes a first moving contact, a second moving contact, and a moving contact assembly; The static contact assembly includes a first static contact, a second static contact, a third static contact, and a fourth static contact; The opening state includes a closing state or a tripping state.

2. The rare earth permanent magnet synchronous switch with capacitive energy storage according to claim 1, characterized in that, Permanent magnets are provided on the first moving contact and the second moving contact.

3. A rare earth permanent magnet synchronous switch with capacitive energy storage according to claim 2, characterized in that, Electromagnets are installed on the first static contact, the second static contact, the third static contact, and the fourth static contact. The electromagnet includes an electromagnet coil and an iron core.

4. A rare earth permanent magnet synchronous switch with capacitive energy storage according to claim 3, characterized in that, The measurement control circuit includes a DC constant current power supply, an energy storage capacitor, and a single-pole double-throw switch.

5. The rare earth permanent magnet synchronous switch with capacitive energy storage according to claim 4, characterized in that, The common connection point of the anode of the DC constant current power supply and the first end of the energy storage capacitor is connected to the first end of the single-pole double-throw switch. The common connection point of the cathode of the DC constant current power supply and the second end of the energy storage capacitor is connected to the second end of the single-pole double-throw switch. The third end and the fourth end of the single-pole double-throw switch are respectively connected to the electromagnet coils of the first static contact, the second static contact, the third static contact, and the fourth static contact.

6. A rare earth permanent magnet synchronous switch with capacitor energy storage according to claim 5, characterized in that When the blade of the single-pole double-throw switch is in the middle, the electrical connection relationship between the DC constant current power supply and the electromagnet coils of the first static contact, the second static contact, the third static contact, and the fourth static contact is disconnected, and the DC constant current power supply charges the energy storage capacitor; When the single-pole double-throw switch closes to the left, the energy storage capacitor provides a pulsed current to the electromagnet coils of the first static contact, the second static contact, the third static contact, and the fourth static contact. Through the electromagnetic force between the electromagnet and the permanent magnet, it controls the connection of the first static contact, the first moving contact, the moving contact assembly, the second moving contact, and the second static contact, and controls the opening state of the synchronous switch to be the closing state; When the single-pole double-throw switch closes to the right, the energy storage capacitor provides a pulsed current to the electromagnet coils of the first static contact, the second static contact, the third static contact, and the fourth static contact. Through the electromagnetic force between the electromagnet and the permanent magnet, it controls the connection of the third static contact, the first moving contact, the moving contact assembly, the second moving contact, and the fourth static contact, and controls the opening state of the synchronous switch to be the tripping state.

7. A rare earth permanent magnet synchronous switch with capacitive energy storage as described in claim 1, characterized in that, Buffer pads are provided at the bottoms of the first static contact, the second static contact, the third static contact, and the fourth static contact.

8. A rare earth permanent magnet synchronous switch with capacitive energy storage according to claim 3, characterized in that, The moving contact assembly, the static contact assembly, and the electromagnet are sealed in the arc suppression chamber through insulating materials.

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