State indication assembly for an electromechanical switching device

Abstract

Apparatuses, systems, and methods for indicating a state of an electromechanical switching device are disclosed. In a particular embodiment, an electromechanical switching device is disclosed that includes one or more fixed contacts, a moveable contact, and a moveable assembly configured to move the moveable contact in relation to the one or more fixed contacts. The switching device is in a closed state when the moveable contact is in contact with the one or more fixed contacts and in an open state when the moveable contact is not in contact with the one or more fixed contacts. The electromechanical switching device also includes an auxiliary state indicator assembly configured for indicating a state of the electromechanical switching device via a state of connection of at least two auxiliary blade circuits of the auxiliary state indicator assembly.

Description

STATE INDICATION ASSEMBLY FOR AN ELECTROMECHANICAL SWITCHING DEVICEFIELD OF THE TECHNOLOGY

[0001] The subject disclosure relates to state indication for an electromechanical switching device.BACKGROUND

[0002] Electromechanical switching devices, such as contactors, relays, or other similar switches, are designed to carry a certain amount of electrical current for certain periods of time. These devices often include a set of fixed contacts and a moveable contact, wherein the moveable contact may be driven into or out of engagement with the fixed contacts by an actuation mechanism (e.g.. a solenoid-based plunger assembly). When an external control signal is supplied, the solenoid coil energizes, causing the plunger to move and drive the moveable contact into a closed position against the fixed contacts, thus completing an electrical circuit and permitting current flow. When the solenoid coil is de-energized, the plunger assembly is returned to an open position by a return spring or a similar mechanism, thereby interrupting current flow.

[0003] In various applications, it is advantageous to determine whether the switching device is in an open state (i.e., the circuit is open and no current is flowing) or in a closed state (i.e., the circuit is closed and current is able to flow). For instance, certain systems require realtime monitoring of the contactor to ensure that power to a dow nstream load is actually disconnected when expected, or to verily that equipment is receiving power as intended. Relying solely on the status of the control signal to the coil does not always accurately reflect the actual mechanical state of the switch because of potential failures or mechanical binding that could prevent the contacts from moving even if the solenoid is energized or deenergized.

[0004] Consequently, an auxiliary state indicator assembly is often integrated into contactors, relays, and other electromechanical switching devices. This assembly typically includes additional circuits, pins, or blade contacts that physically track the position of the moveable assembly. As the moveable contact transitions from open to closed (or vice versa), the auxiliary pins or blades either make or break contact. This mechanical feedback path provides a more reliable indication of whether the switch is truly open or closed, independent of just the energization status of the actuation coil.

[0005] There is therefore a continuing need for innovative configurations of auxiliary' state indicators that can reliably, efficiently, and clearly convey the state of the electromechanical switching device. Such configurations should minimize the risk of erroneous readings, reduce complexity where possible, and provide robust mechanical coupling to the main contactor assembly so as to resist wear and misalignment over time.SUMMARY

[0006] Apparatuses, systems, and methods for indicating a state of an electromechanical switching device are disclosed. In at least one embodiment, an electromechanical switching device is provided that includes one or more fixed contacts, a moveable contact, and a moveable assembly configured to move the moveable contact in relation to the one or more fixed contacts. The moveable contact establishes the closed state of the device when it engages the fixed contacts, and the open state when it is not in engagement. The device further includes an auxiliary state indicator assembly indicating a state of the electromechanical switching device via a state of connection of at least two auxiliary blade circuits of the auxiliary’ state indicator assembly.

[0007] In some examples, conductive pins attached to the moveable assembly may engage or disengage one or more blades to form an auxiliary' circuit that closes in one state and opens in another. In other examples, non-conductive pins may physically separate or allow contact between blades, achieving a similar state-indicating function without relying on direct electrical contact through the pin. By providing multiple auxiliary blade circuits, different states — such as “open,’’ “closed,” or intermediate positions — may be indicated simultaneously or in a redundant manner to enhance reliability7.

[0008] In this way, the disclosed devices, systems, and methods facilitate more accurate realtime monitoring of contactor or relay states, improving the safety, fault tolerance, and diagnostic capabilities of systems that rely on electromechanical switches. These and other objects, features, and advantages will be evident from the detailed description that follows and from an examination of the associated drawings, wherein like reference numerals generally represent like parts across described embodiments.

[0009] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts of exemplary' embodiments of the invention.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a diagram illustrating a cross-sectional view of a portion of an example electromechanical switching device with a state indicator assembly according to at least one embodiment of the present disclosure.

[0010] FIG. 2 is a diagram illustrating an isometric view of a portion of the electromechanical switching device of FIG. 1.

[0011] FIG. 3 is a diagram illustrating an isometric view of another portion of the electromechanical switching device of FIG. 1.

[0012] FIG. 4 is a diagram illustrating an isometric view of a portion of an example electromechanical switching device with a state indicator assembly according to at least one embodiment of the present disclosure.DETAILED DESCRIPTION

[0013] The terminology used herein for describing particular examples is not intended to limit further examples. When the terms “a,” ‘"an,"’ or “the” are used, it should be understood that they encompass both singular and plural forms unless the context clearly indicates otherwise. Similarly, references to implementing a function with multiple elements or entities do not exclude the possibility of implementing the same function with fewer or a single element.

[0014] The phrases “comprises,” “comprising,” “includes,” “including.” and similar terms should be interpreted as open-ended, meaning that additional elements and operations can be incorporated without departing from the disclosed concepts. References to elements being “connected” or “coupled” may encompass direct, indirect, permanent, or removable relationships unless explicitly stated to the contrary. Further, the term “or” should be interpreted as covering all possible combinations, including “A or B,” “A and B,” “A only,” and “B only,” except where the context or explicit language indicates otherwise.

[0015] With reference to the accompanying figures, several example embodiments of the disclosed electromechanical switching device with a state indicator assembly will be described in greater detail. However, these embodiments should not be construed as limiting; variations, modifications, and alternatives can be made without departing from the scope of this disclosure.

[0016] For further explanation, FIG. 1 sets forth a diagram illustrating a cross-sectional view' of a portion of an example electromechanical switching device (100) with a state indicator assembly according to at least one embodiment of the present disclosure. FIG. 2 sets forth a diagram illustrating an isometric view of a portion (200) of the electromechanical switchingdevice (100) of FIG. 1. FIG. 3 sets forth a diagram illustrating an isometric view of another portion (300) of the electromechanical switching device (100) of FIG. 1.

[0017] In general, the switching device 100 includes fixed contacts (not pictured in FIGs. 1-3 for clarity) and a moveable contact 110 that is driven into or out of engagement with the fixed contacts by a moveable assembly 120. In at least one embodiment, the moveable assembly 120 typically comprises a plunger 101, an actuator shaft 102, and a plunger spring 107.

[0018] In an example actuation cycle, when a solenoid coil (not shown) is energized, the generated magnetic field pulls or pushes the plunger 101 in a direction that drives the moveable contact 110 into engagement with the fixed contacts, transitioning the device from an open state (no current flow) to a closed state (current flow). This movement compresses the plunger spring 107, storing mechanical energy. Once the coil is de-energized, the mechanical energy in the plunger spring 107 forces the plunger 101 back tow ard its starting position, disengaging the moveable contact 110 from the fixed contacts and returning the device to its open state. The specifics of the solenoid design (e.g., coil windings, magnetic core geometry) may vary’ based on current and voltage ratings, switching speed requirements, and mechanical constraints.

[0019] In many applications, such as industrial process control, safety-critical systems, or high-power distribution netw orks, it is crucial to confirm whether the switching device 100 is actually open or closed. Depending solely on the status of the solenoid coil can be misleading in situations where mechanical obstructions, component wear, or partial actuator failures might prevent the moveable contact from fully transitioning. Therefore, the disclosed auxiliary state indicator assembly provides an independent and direct mechanical link to the moveable assembly 120, enabling a more accurate real-time indication of the contact state.

[0020] As illustrated in FIG. 1, the electromechanical switching device 100 includes a first conductive pin 123 coupled to the moveable assembly 120. This conductive pin 123 physically moves with the plunger 101 and actuator shaft 102. The auxiliary state indicator assembly, in one embodiment, includes a first auxiliary blade circuit comprising a first blade 122 and a second blade 124. These blades may be fabricated from conductive metals (e.g., copper alloys) chosen for their flexibility, conductivity, and durability under repeated mechanical cycling. In a particular embodiment, each blade is formed of a spring-tempered metal adapted to provide sufficient elasticity for repeated mechanical contact with conductive or non-conductive pins. In a particular embodiment, the blades are manufactured by a stamping process.

[0021] The blades 122, 124 are mounted or positioned so that the first conductive pin 123 caneither bridge the two blades or remain out of contact with them, depending on whether the device 100 is open or closed. When the device is in the open state, the first conductive pin 123 does not make electrical connection between the first blade 122 and the second blade 124. This means the first auxiliary blade circuit is “open,” signaling that the main contacts are open. Conversely, when the device transitions to the closed state, the first conductive pin 123 touches (or otherwise completes a path between) the first blade 122 and the second blade 124, thereby closing that auxiliary circuit and indicating that the main contacts are closed. The moveable assembly is coupled to the auxiliary state indicator assembly in such a way that any change in the position of the moveable contact is transferred directly to the at least one auxiliary blade circuit.

[0022] In a particular embodiment, the at least one auxiliary blade circuit is configured to maintain a default open or closed position in the absence of movement by the moveable assembly. This arrangement provides a direct and mechanically enforced correlation between the position of the moveable contact 110 and the conductivity between blade elements in the auxiliary circuit. Because the first conductive pin 123 is physically attached to the same assembly that carries the moveable contact 110. there is minimal opportunity for an error in state indication caused by partial or failed actuations.

[0023] In addition to the first conductive pin 123, the device 100 may include a second conductive pin 127 for redundant or complementary state indication. As depicted in FIG. 2, the second conductive pin 127 interacts with a second auxiliary blade circuit having a third blade 126 and a fourth blade 128. When the device is in the open state, the second conductive pin 127 physically or electrically couples the third blade 126 and the fourth blade 128, closing that auxiliary circuit. When the device transitions to the closed state, the second conductive pin 127 no longer couples the two blades, causing that auxiliary circuit to open. That is, the auxiliary state indicator assembly comprises a plurality of overlapping blades, each arranged to provide a distinct open-or-closed feedback signal corresponding to the position of the moveable assembly.

[0024] These two conductive-pin-based circuits can be used in tandem. For example, one circuit may only be closed when the main contacts are closed, and the other circuit may only be closed when the main contacts are open. That is, the auxiliary state indicator assembly includes first and second sets of blades positioned at different axial locations along the moveable assembly to provide multiple independent indications of the open or closed state. In a control panel or monitoring system, this arrangement can provide additional clarity by simultaneously conveying that “the device is definitely open” (one circuit closed) or “thedevice is definitely closed'’ (the other circuit closed). That is, the auxiliary state indicator assembly is configured to provide a first electrical signal when the electromechanical switching device is in the open state and a second electrical signal when the electromechanical switching device is in the closed state, the first and second signals being simultaneously readable by a control system. Systems that require fail-safe or redundant feedback loops can benefit from this dual indication.

[0025] In the example of FIGs. 1 and 3. the auxiliary state indicator assembly is mounted to a bracket 140. In this embodiment, the bracket is configured to align each auxiliary blade circuit with a corresponding conductive pin. The moveable assembly and the auxiliary state indicator assembly are configured such that electrical indication of the open state or the closed state occurs at substantially the same time as mechanical separation or engagement of the moveable contact with the one or more fixed contacts.

[0026] By way of example and not limitation, consider a contactor installed in a factory setting to supply power to a motor. During normal operation, when the motor must run, a control signal energizes the coil, pulling the plunger 101 upwards and closing the moveable contact 1 10 against the fixed contacts. Simultaneously, the first conductive pin 123 bridges the gap between the first blade 122 and the second blade 124, closing that auxiliary circuit. Control logic reading the auxiliary' circuit sees continuity and confirms that the contactor is in a closed state.

[0027] When the motor is to be shut down, the coil is de-energized, allowing the plunger spring 107 to push the plunger 101 back to the open position. The moveable contact 1 10 separates from the fixed contacts, interrupting current flow. Correspondingly, the first conductive pin 123 no longer connects the first and second blades, and that auxiliary circuit reads open, signifying an open main contact condition.

[0028] Redundancy can be added by having the second conductive pin 127 or additional non- conductive pins that confirm the inverse condition. For instance, the second conductive pin 127 might close an auxiliary blade circuit only when the device is open. This way, if the system reads that the “open circuit” sensor is active while the “closed circuit” sensor is inactive, it knows unequivocally that the contactor is open.

[0029] For further explanation, FIG. 4 sets forth a diagram illustrating an isometric view of a portion 400 of an example electromechanical switching device with a state indicator assembly according to at least one embodiment of the present disclosure. In this alternative embodiment, the auxiliary state indicator assembly utilizes a first non-conductive pin 403 attached to the moveable assembly 420. Instead of completing an electrical path by bridgingtwo blades, the non-conductive pin 403 physically separates or allows contact between a fifth blade 402 and a sixth blade 404. In this embodiment, the blades 402. 404 themselves may be spring-biased to remain in contact unless physically forced apart by the pin 403.

[0030] When the switching device is in the open state, the non-conductive pin 403 does not insert between the fifth blade 402 and the sixth blade 404, allowing them to touch or otherwise be electrically connected. This signifies that the auxiliary’ blade circuit in question is “closed,’7corresponding to the open state of the main contacts. That is, the auxiliary blade circuit is configured to remain electrically closed unless forcibly opened by a conductive pin, thereby enabling a normally closed auxiliary' indication of the open state of the electromechanical switching device. When the device transitions to the closed state, the non- conductive pin 403 drives between the fifth blade 402 and sixth blade 404, forcing them apart and opening that auxiliary circuit.

[0031] Similarly, a second non-conductive pin 407 may be employed for a second auxiliary circuit comprising a seventh blade 406 and an eighth blade 408. In this arrangement, the pin 407 either separates or allows contact between the two blades, furnishing yet another independent indicator of whether the switching device is open or closed. As shown in FIG. 4. the positioning of the non-conductive pin 407 relative to the seventh and eighth blades changes as the moveable assembly 420 moves, thereby reflecting the true mechanical state of the main contacts.

[0032] These two conductive-pin-based circuits can be used in tandem. For example, one circuit may only be closed when the main contacts are closed, and the other circuit may only be closed when the main contacts are open. In a control panel or monitoring system, this arrangement can provide additional clarity by simultaneously conveying that “the device is definitely open” (one circuit closed) or “the device is definitely closed” (the other circuit closed). Systems that require fail-safe or redundant feedback loops can benefit from this dual indication.

[0033] In the example of FIG. 4, the auxiliary state indicator assembly is mounted to a bracket (not pictured). In this embodiment, the bracket is configured to align each auxiliary blade circuit with a corresponding non-conductive pin.

[0034] Although not pictured, in an alternative embodiment of the present invention, an auxiliary’ state indicator assembly includes one or more auxiliary' circuits with a non- conductive pin and one or more auxiliary' circuits with a conductive pin.

[0035] The geometry’, materials, and positioning of the pins and blades may be tailored to specific design requirements. For instance, in high-current applications subject to significantheat or vibration, the mechanical robustness of the indicator assembly is paramount. Designers may choose thicker or more rigid blades, reinforced pin mountings, or use insulating materials with higher temperature tolerances.

[0036] Additionally, some embodiments may employ sealed or encapsulated housings to protect the indicator assembly from contamination, dust, or moisture — factors that could otherwise compromise accurate state indication. Gaskets, O-rings, or potting compounds may be used to seal off the region where the pins engage the blades, ensuring reliable operation over extended lifespans.

[0037] As depicted in FIG. 1, the switching device 100 may include a plunger 101 and a plunger spring 107 coupled to a fixed structure (e.g., the device housing) and to the plunger 101. When the coil is energized, the plunger 101 moves the moveable contact 110 to close the circuit; when the coil is de-energized, the compression force in the plunger spring 107 pushes the plunger 101 back, returning the device to the open state. In some embodiments, the plunger 101 may be magnetically latched in one position, requiring a reverse current or a mechanical release to change states. The auxiliary state indicator assemblies described herein remain valid for these alternative latching arrangements, provided that the pm movements still correlate accurately with the moveable contact position.

[0038] In practice, the outputs of the auxiliary' blade circuits may be wired to external control or monitoring equipment. For instance, if a conductive pin arrangement is used, each blade circuit could be monitored by a low- voltage sensor or logic input. The presence or absence of continuity in that circuit would then drive a status LED on a control panel, or be fed into a programmable logic controller (PLC) for automated supervisory control. The reliability7of the mechanical coupling means that if the main contacts fail to move (e.g., become welded shut or jammed open), the corresponding auxiliary’ circuit will fail to indicate the expected state, prompting a fault signal.

[0039] While the detailed description focuses on certain mechanical arrangements of pins and blades, many variations are possible. For instance, the blades could be replaced or supplemented by spring-loaded pogo pins, leaf springs, or Hex-circuit traces. Conductive pins could be replaced with conductive rollers, or the device could use optical, magnetic, or capacitive sensors triggered by the mechanical motion of the plunger. The fundamental concept remains the same: to provide a reliable, direct indication of the actual position of the moveable contact relative to the fixed contacts.

[0040] Implementing a mechanically coupled auxiliary state indicator assembly according to embodiments described above yields several distinct advantages, including reducing thelikelihood of false state indications caused by coil malfunction or partial actuation. The auxiliary state indicator assemblies described above also provide an accessible means for external systems to verify open or closed status at the device level. Moreover, the hardware design can be relatively simple and robust, requiring few additional components. In high- reliability applications, multiple redundant circuits can be employed without significantly complicating the overall contactor design.

[0041] From the foregoing detailed description, it will be apparent that various modifications, substitutions, and improvements can be made without departing from the spirit or scope of the present disclosure. The described embodiments are illustrative and not limiting; the features described may be combined in different ways, modified for particular usage scenarios, or applied to various types of electromechanical switches. The scope of the present disclosure is limited only by the language of the following claims.

Claims

CLAIMSWhat is claimed is:

1. An electromechanical switching device comprising: one or more fixed contacts; a moveable contact; a moveable assembly configured to move the moveable contact in relation to the one or more fixed contacts; wherein the electromechanical switching device is in a closed state when the moveable contact is in contact with the one or more fixed contacts and in an open state when the moveable contact is not in contact with the one or more fixed contacts; and an auxiliary state indicator assembly configured for indicating a state of the electromechanical switching device via a state of connection of at least two auxiliary blade circuits of the auxiliary' state indicator assembly.

2. The electromechanical switching device of claim 1 further comprising: a first conductive pin coupled to the moveable assembly; wherein the auxiliary state indicator assembly includes a first auxiliary blade circuit having: a first blade; and a second blade; the first blade and the second blade positioned relative to the first conductive pin such that: when the switching device is in the open state, the first conductive pin is not coupled to the first blade and the second blade; and when the switching device is in the closed state, the first conductive pin is coupled to the first blade and the second blade.

3. The electromechanical switching device of claim 1 further comprising: a second conductive pin coupled to the moveable assembly; wherein the auxiliary' state indicator assembly includes a second auxiliary blade circuit having: a third blade; and a fourth blade; the third blade and the fourth blade positioned relative to the second conductive pin such that: when the switching device is in the open state, the second conductive pin is coupled to the third blade and the fourth blade; andwhen the switching device is in the closed state, the second conductive pin is not coupled to the third blade and the fourth blade.

4. The electromechanical switching device of claim 1 further comprising: a first conductive pin coupled to the moveable assembly; wherein the auxiliary state indicator assembly includes a first auxiliary7blade circuit having: a first blade; and a second blade; the first blade and the second blade positioned relative to the first conductive pin such that: when the switching device is in the open state, the first conductive pin is not coupled to the first blade and the second blade; and when the switching device is in the closed state, the first conductive pin is coupled to the first blade and the second blade; and a second conductive pin coupled to the moveable assembly; wherein the auxiliary7state indicator assembly includes a second auxiliary blade circuit having: a third blade; and a fourth blade; the third blade and the fourth blade positioned relative to the second conductive pin such that: when the switching device is in the open state, the second conductive pin is coupled to the third blade and the fourth blade; and when the switching device is in the closed state, the second conductive pin is not coupled to the third blade and the fourth blade.

5. The electromechanical switching device of claim 1 further comprising: a first non-conductive pin coupled to the moveable assembly; wherein the auxiliary7state indicator assembly includes a third auxiliary blade circuit having: a fifth blade; and a sixth blade; the fifth blade and the sixth blade positioned relative to the first non-conductive pin such that: when the switching device is in the open state, the first non-conductive pin does not separate the fifth blade and the sixth blade; and when the switching device is in the closed state, the first non-conductive pin separates the fifth blade and the sixth blade.

6. The electromechanical switching device of claim 1 further comprising: a second non-conductive pin coupled to the moveable assembly; wherein the auxiliary state indicator assembly includes a fourth auxiliary blade circuit having: a seventh blade; and an eighth blade; the seventh blade and the eighth blade positioned relative to the second non- conductive pin such that: when the switching device is in the open state, the second non-conductive pin separates the seventh blade and the eighth blade; and when the switching device is in the closed state, the second non-conductive pin does not separate the seventh blade and the eighth blade.

7. The electromechanical switching device of claim 1 further comprising: a first non-conductive pin coupled to the moveable assembly; wherein the auxiliary state indicator assembly includes a third auxiliary blade circuit having: a fifth blade; and a sixth blade; the fifth blade and the sixth blade positioned relative to the first non-conductive pin such that: when the switching device is in the open state, the first non-conductive pin does not separate the fifth blade and the sixth blade; and when the switching device is in the closed state, the first non-conductive pin separates the fifth blade and the sixth blade; and a second non-conductive pin coupled to the moveable assembly; wherein the auxiliary state indicator assembly includes a fourth auxiliary blade circuit having: a seventh blade; and an eighth blade; the seventh blade and the eighth blade positioned relative to the second non- conductive pin such that: when the switching device is in the open state, the second non-conductive pin separates the seventh blade and the eighth blade; and when the switching device is in the closed state, the second non-conductive pin does not separate the seventh blade and the eighth blade.

8. The electromechanical switching device of claim 1 further comprising: a plunger; anda plunger spring coupled to a fixed structure and to the plunger.

9. The electromechanical switching device of claim 8, wherein the plunger spring is configured to apply a preload force on the plunger that forces the plunger away from the fixed structure.

10. The electromechanical switching device of claim 1 further comprising a housing that encloses the auxiliary’ state indicator assembly, wherein the housing is configured to protect the at least one auxiliary blade circuit from dust and moisture.

11. The electromechanical switching device of claim 1, wherein the at least one auxiliary7blade circuit is configured to maintain a default open or closed position in the absence of movement by the moveable assembly.

12. The electromechanical switching device of claim 1, wherein the auxiliary state indicator assembly is mounted to a bracket, the bracket being configured to align each auxiliary blade circuit with a corresponding conductive or non-conductive pin.

13. The electromechanical switching device of claim 1, wherein the auxiliary state indicator assembly is configured to couple with an external monitoring or control system.

14. The electromechanical switching device of claim 1, w herein the moveable assembly and the auxiliary7state indicator assembly are configured such that electrical indication of the open state or the closed state occurs at substantially the same time as mechanical separation or engagement of the moveable contact with the one or more fixed contacts.

15. The electromechanical switching device of claim 1, wherein each blade in the at least one auxiliary blade circuit is formed of a spring-tempered metal adapted to provide sufficient elasticity for repeated mechanical contact with the first conductive pins.

16. The electromechanical switching devrce of claim 1, wherein the auxiliary state indicator assembly includes first and second sets of blades positioned at different axial locations along the moveable assembly to provide multiple independent indications of the open or closed state.

17. The electromechanical switching device of claim 1, wherein the auxiliary state indicator assembly is configured to provide a first electrical signal when the electromechanical switching device is in the open state and a second electrical signal when the electromechanical switching device is in the closed state, the first and second signals being simultaneously readable by a control system.

18. The electromechanical switching device of claim 1 wherein the moveable assembly is coupled to the auxiliary state indicator assembly in such a way that any change in the position of the moveable contact is transferred directly to the at least one auxiliary blade circuit.

19. The electromechanical switching device of claim 1, wherein the auxiliary state indicator assembly comprises a plurality of overlapping blades, each arranged to provide a distinct open-or-closed feedback signal corresponding to the position of the moveable assembly.

20. The electromechanical switching device of claim 1, wherein at least one auxiliary blade circuit is configured to remain electrically closed unless forcibly opened by a conductive pin. thereby enabling a normally closed auxiliary indication of the open state of the electromechanical switching device.

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