Relay Regulation and Surge Control

Abstract

A system for suppressing transient currents in a circuit to prevent damage to a switching device such as a relay and / or a solid-state switching device is provided. An associated automatic transfer switch (ATS) system (300) includes a main power line terminated at a line cap (302) to receive power from a main power source and an auxiliary power line terminated at a line cap (304) to receive power from an auxiliary power source. The system (300) also includes an output terminal (306) for connecting to an output load such as a piece of electronic equipment. The output terminal (306) can be a female socket so that the system (300) can be directly connected to a male power port of a piece of equipment. The system (300) also includes a micro ATS module (308) that operates to sense a power interruption or signal quality degradation of a power signal of at least the main power source, and in response, switches a power supply from the main power source to the auxiliary power source. A surge suppression circuit (310) is inserted in the auxiliary power line between the module (308) and the line cap (304).

Description

[0001] Cross-references

[0002] This application claims priority to provisional U.S. Patent Application No. 62 / 817,456, filed on March 12, 2019, entitled “RELAY CONDITIONING AND POWERSURGE CONTROL” (“parent application”), and claims priority to the parent application to the maximum extent permitted by applicable laws and regulations. The parent application is incorporated herein by reference in its entirety.

[0003] Incorporated Documents

[0004] The following applications (hereinafter referred to as "incorporated documents") are incorporated herein by reference in their entirety:

[0005] 1) U.S. Provisional Patent Application No. 61 / 372,752, filed on February 26, 2013, entitled “HIGHLY PARALLEL REDUNDANT POWERDISTRIBUTION METHODS”;

[0006] 2) U.S. Patent Application Publication No. US-2012 / 0181869-A1, entitled “PARALLEL REDUNDANT POWER DISTRIBUTION,” published on July 19, 2012; U.S. Patent Application Serial No. 13 / 208,333, filed on August 11, 2011, entitled “PARALLEL REDUNDANT POWER DISTRIBUTION,” (the “'333 Application”), which is a non-provisional application of and claims priority to U.S. Provisional Patent Application No. 61 / 372,752, filed on August 11, 2010, entitled “HIGHLY PARALLEL REDUNDANT POWER DISTRIBUTION METHODS,” and U.S. Provisional Patent Application No. 61 / 372,756, filed on August 11, 2010, entitled “REDUNDANT POWER DISTRIBUTION,”

[0007] 3) U.S. Patent No. 8,004,115 from U.S. Patent Application Serial No. 12 / 569,733, filed on September 29, 2009, entitled “AUTOMATIC TRANSFER SWITCH MODULE,” which is a continuation-in-part of U.S. Patent No. 12 / 531,212, filed on September 14, 2009, entitled “AUTOMATIC TRANSFER SWITCH,” which is the U.S. national phase of PCT Application US2008 / 57140, filed on March 14, 2008, entitled “AUTOMATIC TRANSFER SWITCH MODULE,” which claims priority to U.S. Provisional Application No. 60 / 894,842, filed on March 14, 2007, entitled “AUTOMATIC TRANSFER SWITCH MODULE”; and

[0008] 4) U.S. Patent Application Serial No. 13 / 108,824, filed on May 16, 2011, entitled “POWER DISTRIBUTION SYSTEMS AND METHODOLOGY,” U.S. Patent Application Publication No. US-2012-0092811, is a continuation-in-part of U.S. Patent Application Serial No. 12 / 891,500, filed on September 27, 2010, entitled “POWER DISTRIBUTION METHODOLOGY,” which is a continuation-in-part of International Patent Application No. PCT / US2009 / 038427, filed on March 26, 2009, entitled “POWER DISTRIBUTION SYSTEMS AND METHODOLOGY,” which claims the entirety of International Patent Application No. PCT / US2009 / 038427, filed on March 26, 2008, entitled “POWER DISTRIBUTION SYSTEMS AND METHODOLOGY,” which claims the entirety of International Patent Application No. PCT / US2009 / 038427, filed on March 26, 2008, entitled “POWER DISTRIBUTION Priority to U.S. Provisional Application No. 61 / 039,716 entitled "METHODOLOGY".

[0009] 5) U.S. Patent No. 8,374,729, which is derived from U.S. Patent Application Serial No. 12 / 569,377, filed on September 29, 2009, entitled “SMART ELECTRICAL OUTLETS AND ASSOCIATED NETWORKS,” which is a continuation of U.S. Patent Application Serial No. 12 / 531,226, filed on February 16, 2010, entitled “SMART ELECTRICAL OUTLETS AND ASSOCIATED NETWORKS,” which is the U.S. National Phase of PCT / US2008 / 057150, filed on March 14, 2008, entitled “SMART NEMA OUTLETS AND ASSOCIATED NETWORKS,” which in turn claims the U.S. National Phase of PCT / US2008 / 057150, filed on March 14, 2007, entitled “SMART NEMA OUTLETS AND ASSOCIATED NETWORKS” is a patent application filed on July 24, 2008. The patent application claims priority to U.S. Provisional Application No. 60 / 894,846, filed on July 24, 2008. Technical Field

[0010] Embodiments of the present invention relate to the design and operation of transfer switches connected to AC powered equipment. Such equipment has many uses; we note that the use of the present invention generally relates to control aspects of the operation of power distribution circuits and circuits and / or connected automatic transfer switch (ATS) equipment. The present invention also applies to the design and operation of power distribution equipment, such as manual or automatic transfer switches (ATS), and particularly equipment used in mission critical environments (such as medical contexts, power utility grids) or in data centers or telecommunications environments. Background Art

[0011] Recently, OEM AC to DC power supply manufacturers have introduced to the market power supplies (which are commonly used in electronic data processing (EDP) equipment) that have unusually large capacitors connected directly across the AC mains to build a low-pass common mode filter designed to capture any high-order ringing energy entering or leaving the AC to DC power supply on the AC line. This is done to minimize cost and achieve FCC certification. In more traditional power supply design practices, a relatively small inductor is placed between a matching size filter capacitor and the AC mains to control the exposure of the AC mains to the discharge of the capacitor applied directly across the AC mains. However, the manufacturers of those power supplies have found that it is cheaper to add a relatively large capacitor across the AC mains and use cheaper and noisier components in the power supply, and not increase the capacity of the inductor (a more expensive component) to match the larger capacity of the filter capacitor. The disadvantage of this approach is that under certain conditions, the energy stored in the capacitor can discharge rapidly along the AC line and cause high transient currents.

[0012] These abnormal power supplies with excessive capacitance have capacitors that are 10 or more times the size of previous designs. This is not good design practice, but there are no electrical design or safety standards that govern this design practice. Summary of the invention

[0013] The inventors have recognized that these abnormal power supplies with excessive capacitance can cause problems when transferring AC rapidly from one source to another, such as in a manual or automatic transfer switch (ATS). If the AC line on the primary side (side A in this example) is disconnected at or near the peak of the AC cycle, the filter capacitor will charge to this voltage. If the ATS accidentally transfers the load to the backup power source (side B in this example) and it is in the opposite half cycle or close to this half cycle in voltage state, the capacitor on the input of the equipment load can be connected to a low impedance voltage source of polarity that is significantly opposite to the polarity to which it is charged. In this case, the capacitor can be charged to as much as positive 300 volts, and the opposite voltage transferred to the source can be as much as negative 350 volts (or vice versa); the resulting discharge is as much as 650 to 700 volts at 1 to 3 microfarads. Considering the average resistance of most loads, this will not be a problem, and the energy of the current will be absorbed without damage, but the fault side of the ATS is often connected to a low impedance plugstrip with multiple pieces of EDP equipment on it. These pieces of EDP equipment often have the same input protection capacitors on them, reducing the transient impedance to very low values. Therefore, when the relay contacts or thyristors are first closed on the ATS connected to the power supply in question, very high currents are experienced in an instant. Recent results measured in laboratory tests have shown that short-duration currents of 250 amps or more can easily be obtained, and this has the potential to cause liquefaction of the parts of the relay contacts that are closest to the other relay contacts. The transient current flow is so high that the effect across the contacts is very similar to that of an arc welder. Depending on the level and duration of the current flow and the maximum voltage level seen, this contact arcing can cause micro-welding of the relay contacts or damage to the solid-state switch components. Contact relays often stick when they resolidify, causing false trips. Solid-state switch components may be damaged or fail catastrophically and may actually smoke and / or catch fire.

[0014] This problem affects any relay-based or solid-state-based ATS, causing it to malfunction and / or fail. This can cause unexpected downtime for AC / DC powered equipment due to the ATS not working. This can cause serious problems if mission-critical equipment is shut down due to power delivery failure. Users can recognize that designers of EDPs and other types of equipment for data center use often assume that the power quality in the data center is well controlled and of good quality. Therefore, the use of traditional methods to protect against transient power spikes is often limited and / or non-existent. Another problem with traditional methods is that they are often too large to be used in crowded data center cabinets with limited free space and limited equipment form factors. The present invention provides a variety of devices and methods to increase the probability or actively prevent ATS units or other equipment from failing due to these conditions and meet other constraints (such as form factor, energy efficiency, cost, etc.) often required by data centers and other environments.

[0015] Switching mechanisms for electrical connections are currently divided into: solid-state based switching devices (triacs, etc.), which switch very quickly but have the disadvantage of being inefficient, with approximately 0.5-2% of the power sent through them lost as heat; and mechanical relay based, which switch much slower but are much more efficient with minimal heat losses. Many devices, including ATS units, use solid-state switches and / or mechanical relays with the advantages and disadvantages described above to control power. Regardless of the type of switch, whether a solid-state relay or a mechanical relay, in many applications either or both of transfer time and efficiency are important and may be critical. ATS switches are available on the market that use one, the other, or a combination of these two switching technologies.

[0016] A key example is the design and management of power distribution in a data center, as power supplies used in modern electronic data processing (EDP) equipment can often only tolerate very brief power interruptions. For example, the Computer and Business Equipment Manufacturers Association (CBEMA) guidelines used in power supply design recommend a maximum power outage time of 20 milliseconds or less. If the power delivery to the power supply is interrupted for longer than this time, the EDP equipment that is in operation will stop or restart. Modern power supplies can often only tolerate maximum power outage times as low as approximately 12-14 milliseconds, which we have measured and observed in many past and current EPD devices.

[0017] This is a very important issue in the design of manual or automatic transfer switches (ATS) to switch between two or more power sources (for example, due to power failures such as power outages or power quality issues), as well as other power distribution equipment used with EPD equipment. The number of modern devices that now incorporate embedded processor control is huge and growing rapidly. For various reasons (such as cost or size), many of these devices do not have dual power supplies. The programs running on these devices may incorporate algorithms that "learn" over time to improve the performance of the device. The data stored to perform this operation may not be written to a persistent data storage device. In that case, an ATS unit is typically used to ensure that the connected equipment operates without any downtime. There are many other examples of devices that incorporate power in which the speed and / or efficiency of the switching function are important issues and reducing or eliminating the vulnerability to these transient current and voltage issues would be of great benefit.

[0018] The present invention relates to reducing or eliminating the vulnerability of certain equipment, particularly the vulnerability of automatic transfer switches to high transient current and / or voltage events (much higher than the rated capacity of relays and / or solid-state switchgear used in the ATS) that may damage or destroy the connected ATS unit(s). In particular, the present invention relates to providing an apparatus and method for reducing or eliminating the vulnerability of the connected ATS unit(s). This can be accomplished through a design and / or relay conditioning method that can be retrofitted as an external device to a deployed automatic transfer switch or that can be integrated into the ATS structure, which reduces or eliminates the vulnerability of the ATS to high transient current and / or voltage issues.

[0019] Data center cabinets are very crowded, and therefore meeting form factor and space constraints can be a very important part of the present invention. Contributing factors are: the limiting consideration in many ATS designs is that the size of the relays that can be used is limited by the requirement that the ATS switches are fast enough. This means that the relay must be actuated quickly enough to complete the power transfer within the required time frame to keep the connected equipment running without downtime caused by power delivery interruptions. Therefore, the design of the relay must have a contact gap, armature mass, and coil that meet the actuation speed requirements. This means that the relay gap needs to be small enough and the armature mass (including the size of the attached contacts) is low enough to achieve the necessary actuation speed.

[0020] These required characteristics limit the ability of the relay to absorb energy and thus limit its ability to tolerate these high transient current and / or voltage events without damage or destruction. Silicon-based switching devices also have limitations on the energy they can absorb from high transient current and / or voltage events without damage or destruction. A further complicating factor is that relays and solid-state switching devices that have greater tolerance to high current and / or voltage events are often larger and therefore may not fit into the available space in the desired application. Other solutions (such as the use of inductors, chokes, or other traditional methods of addressing surge currents) are often too large to fit into the space required for a particular application.

[0021] Some objects of the present invention include the following:

[0022] An apparatus, design and method are provided to reduce or eliminate the vulnerability of ATS units or other vulnerable equipment to high transient current and / or voltage events within a desired form factor and within space and cost constraints. The apparatus, design and method can be implemented as a retrofit solution to existing ATS installations and / or equipment, or as an upgrade to the design of current and future ATS equipment or other equipment that can be used to reduce or eliminate this problem.

[0023] In accordance with the present invention, these and other objectives are addressed by providing various systems, components, designs, and processes for improving ATS functionality. As discussed below, many aspects of the present invention are applicable to a variety of environments. However, the present invention has particular advantages in data center applications. In this regard, the present invention provides considerable flexibility in dealing with high transient current and / or voltage issues associated with ATS unit functionality. The present invention is advantageous in designing equipment for distributing power to server farms such as those used by companies such as Google or Amazon or cloud computing providers.

[0024] According to one aspect of the present invention, a method and apparatus for suppressing transient currents in a circuit to prevent damage to a switching device such as a relay and / or a solid-state switching device ("utility") is provided. The utility relates to a transfer switch system (such as an ATS) comprising a switch unit and a surge suppression circuit. The switch unit has a first input for receiving a first power signal, a second input for receiving a second power signal, and an output for providing a power signal to a connected load. Each input provides a power signal via a power line extending between the switch and a power outlet associated with a power source. The switch unit also includes a switch for selectively connecting one of the first input and the second input to the output according to a power signal state of at least one of the first power signal and the second power signal. The power suppression circuit suppresses surges at the switch unit. The circuit is disposed either between the switch unit and one of the power outlets, or between the switch unit and the load. Thus, the transfer switch system resists switch damage associated with surges.

[0025] One or more surge suppression circuits may be associated with an automatic transfer switch system. In one embodiment, each of the first power line and the second power line includes a first end for connecting to one of the power sockets, a second end for connecting to the switch unit, and a surge suppression circuit disposed in-line on one of the first power line and the second power line, between the first end and the second end of the power line. In the case where the switch unit is configured so that the first power source is the main power source, the surge suppression circuit may be disposed between the switch unit and the second socket. Alternatively, a surge suppression circuit may be provided on the output, on two inputs, on one input and output, and the like. The power socket may be a socket of one or more wiring boards. For example, a first wiring board or a first socket of a wiring board may be associated with a first power source, and a second wiring board or a second socket of a wiring board may be associated with a second power source. In this way, the first input end and the second input end of the switch unit may be connected to the first power source and the second power source. The wiring board may also have a surge suppression function. In this regard, it has been found that in some cases the conventional surge suppression function of a patch panel is insufficient to protect the contact surfaces of an automatic transfer switch, but according to the present invention, appropriate surge protection can be added to one or more outlets of a patch panel (e.g., outlets designated as automatic transfer switch outlets of the panel).

[0026] The switch unit is preferably operative to switch from a first state in which the first input is connected to the output and a second state in which the second input is connected to the output in response to detecting one of a power interruption and a degradation of a first power signal from one of the power sources. The switch may include one or more electromechanical relays or solid-state switches. The surge suppression circuit may optionally be integrated into the switch housing.

[0027] According to another aspect of the invention, a relay of an automatic transfer switch can be adjusted to better resist surge events. It has been found that if the contact surface of the relay is adjusted by changing the shape, texture or other morphology of the contact surface, the relay will better resist failure due to surge events. This can be achieved by applying a power signal to the relay that is sufficient to change the morphology of the contact surface.

[0028] The corresponding utility involves providing a switch unit including a contact surface and applying an electrical signal sufficient to cause a desired change in the morphology of the contact surface to the contact surface. Specifically, the switch unit includes a first input terminal and a second input terminal for receiving a first power signal and a second power signal, an output terminal for providing a power signal to a connected load, and a switch for selectively connecting one of the first input terminal and the second input terminal to the output terminal according to the power signal state of at least one of the first power signal and the second power signal. The switch unit includes an electromechanical relay having a contact surface for making electrical contact between an armature of the relay and a connecting circuit. For example, the contact surface can be mounted on the armature or can be a part of an electrode for establishing an electrical connection with the armature. The electrical signal is preferably sufficient to cause at least a partial state change of the contact surface, for example, a part of the contact surface can become temporarily melted. The electrical signal can be applied directly to the contact surface or can be applied to the switch unit via the first and second input terminals. Alternatively, the contact surface can be manufactured to have a desired morphology to resist damage caused by surges (for example, by molding the contact surface into a desired morphology) or can be machined into a desired morphology.

[0029] According to yet another aspect of the present invention, a system for adjusting the contact surface of an automatic transfer switch is provided. As described above, it has been found that the contact surface can be adjusted to change the morphology of the contact surface so that the automatic transfer switch is less susceptible to damage due to surges. Therefore, a system can be provided to adjust the contact surface by applying a power signal directly to the contact surface or to an automatic transfer switch including the contact surface.

[0030] The system includes a power signal generator, a first output terminal and a second output terminal associated with the power signal generator, and a controller. The power signal generator is operated to generate a power signal. The first output terminal and the second output terminal are suitable for being connected to the first input terminal and the second input terminal connected to the contact surface directly or via an automatic transfer switch, wherein the automatic transfer switch includes an electromechanical relay and the contact surface involves making electrical contact between the armature of the relay and the connected circuit. The controller is associated with the power signal generator and is used to control the power signal generator to apply an electric signal to the contact surface, wherein the electric signal is sufficient to cause the morphology of the contact surface to change. It will be recognized that the parameters that can be involved in this regard include the voltage of the signal, the current of the signal, the time of applying the signal, the frequency of the signal, the number of cycles of applying the signal therebetween, and the properties of any impedance capacitance or other electrical characteristics associated with the flow path of the signal. In addition, when applying an appropriate signal, the material of the contact surface, the shape of the contact surface, the dimensions of the contact surface and other characteristics of the contact surface can be considered.

[0031] An associated method involves providing a power signal generator, connecting the output of the power signal generator to the contact surface (directly or indirectly), and controlling the power signal generator to apply one or more electrical signals to the contact surface sufficient to cause a morphological change in the contact surface. In a preferred embodiment, a series of signals or cycles of increasing power are applied to the contact surface so that an earlier signal can make the contact surface more tolerant of later signals. The method may also include separating the armature from the connected circuit at the contact surface and inspecting the contact surface to ensure that it has the desired characteristics for resisting damage due to surges.

[0032] According to another aspect of the present invention, a utility for supplying power to an electrical device is provided. For example, the electrical device may be an automatic transfer switch or another device that is sensitive to surges, such as a device that includes an electromechanical relay. The utility includes a first wire cap for connecting to the electrical device, a second wire cap for connecting to a power supply, a power line extending between the first wire cap and the second wire cap, and a surge suppression circuit disposed in a straight line on the power line between the first wire cap and the second wire cap. For example, the first wire cap may be a bus cap for mating with a male electrical port of an electrical device (e.g., an ATS unit), and the second wire cap may be a male wire cap for inserting into a female socket of a power supply unit (such as a terminal block). As a further example, the first wire cap may be connected to the output of the ATS and the second wire cap may be connected to a piece of equipment. The surge suppression circuit may be disposed in a housing in the power line inserted between the wire caps. The housing is preferably relatively small, such as having a maximum dimension not exceeding about 6 cm and a volume not exceeding about 50 cm 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0033] For a better understanding of the present invention and further advantages thereof, reference is now made to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0034] The present disclosure is described in conjunction with the accompanying drawings:

[0035] Figure 1 An example of an operating environment of an ATS that may include a surge suppression circuit according to the present invention is shown.

[0036] Figure 2 One possible example of a compact surge suppression circuit according to the invention is shown.

[0037] Figure 3-6 Examples of several possible form factors are shown for implementing an aspect of the invention in an external device or as part of an ATS design.The Zonit miniature automatic transfer switch is used as a typical example of a very compact ATS.

[0038] Figures 7A-7C is a photograph showing one possible example of a surge suppression circuit in a power line according to the present invention.

[0039] Figures 8A-8C Shared are photographs of contact surfaces without conditioning and with different numbers of conditioning cycles according to the invention.

[0040] Fig. 9 One possible example of a relay regulator according to the present invention is shown, which tests, times and groups the relays being tested, as described herein.

[0041] Figures 10A-10C Shows Fig. 9 The form factor of the relay regulator.

[0042] Fig.11 is a voltage versus time graph illustrating a surge condition addressed in accordance with the present invention.

[0043] Fig.12 Shown with Fig.11 Corresponding voltage and current graphs.

[0044] Fig.13 is a schematic diagram of an ATS that may be used with a surge suppression circuit according to the present invention.

[0045] Figure 14-16 is a schematic diagram illustrating the operation of an external surge suppression circuit according to the present invention.

[0046] Figure 17-19 is a schematic diagram illustrating the operation of an internal surge suppression circuit according to the present invention.

[0047] In the accompanying drawings, similar components and / or features may have the same reference numeral. In addition, various components of the same type may be distinguished by following a first (e.g., numeric) label with a second (e.g., alphabetic) label that distinguishes between similar components. If only the first reference numeral is used in the specification, the description applies to any one of the similar components having the same first reference numeral, regardless of whether the second reference numeral is present. DETAILED DESCRIPTION

[0048] This section describes methods for building multiple circuits in multiple devices, such as power lines, ATS devices, or other devices. Many examples are related to compact ATS units. While this is considered an important use case, it should be recognized that the present invention is applicable to a variety of other environments. Therefore, the following description should be understood as exemplary rather than limiting.

[0049] In one example, in conjunction with the power lines associated with the ATS, the surge circuit of the present invention can be implemented in-line with a very small form factor. This has multiple advantages, as detailed below. One point to note is that, depending on the design of a given ATS unit, the in-line surge circuit can be placed on the output of the ATS unit or on one or both power inputs. This is because an ATS designed and / or configured to use the "A" side as the preferred and primary power source only requires the "B side" input (auxiliary power source) to have a surge-protected power line. Most ATS devices have a preferred power source, i.e., the "A" primary source. An ATS developed by Zonit Structural Solutions (Zonit) in Boulder, Colorado, allows the user to select which source to use as the primary source and change the primary source as desired. If the "A" source is available and optionally has sufficient quality for some designs that measure power quality, the ATS will use the "A" source. Once the "A" power drops far enough and long enough, the ATS transfer from the "A side" to the "B side" is completed. Normal is defined as a power quality disturbance that can last up to 4 milliseconds before it becomes a power outage. Therefore, most ATS units monitor the "A" side power and then switch to the "B" side power as soon as possible after 4 milliseconds.

[0050] This means that if the power on the "A" side and the "B" side are out of phase (which is very common in modern data centers that use two hot phases for 208V power distribution or three-phase power distribution (which has become the most common method due to the increase in power levels on the racks)), then the difference in voltage levels between the power supplies can cause high transient current and / or voltage surges in the above scenario. Therefore, it should be noted that this difference in voltage level can be due to differences between the voltages, or due to differences between the voltage caused by the capacitor charged by one of the signals and the voltage of the other signal in the signal, rather than due to surges in one of the signals. Therefore, surge protection circuits in one or both power lines do not address this problem. This is not a problem when transferring from the "B side" to the "A side". This is true because when the transfer from the "B" side to the "A" side is performed, both sides are powered and operating and may be of sufficient quality. In this case, the ATS can time the transfer to occur at the zero crossing of the "A" side power being transferred to, so high transient current and / or voltage events generally do not occur.

[0051] The following Figure 1 An operating environment for an ATS is shown (in this case, one form factor of a miniature ATS developed by Zonit). Thereafter, examples of surge suppression or surge control circuits and various form factors and alternative implementations will be described.

[0052] Figure 1 2 shows an exemplary diagram of the application of the automatic transfer switch 50. Equipment 26 can be installed in a rack 25 having a main wiring board 21 and an auxiliary wiring board 22 mounted on the opposite side of the rack 25. It will be appreciated that the sockets associated with the main power supply and the auxiliary power supply can alternatively be provided in a single plug board, provided from a rack-mounted power supply unit, or provided via other means. The wiring boards 21 and 22 shown include a plurality of sockets 23 and 24, respectively. The main and auxiliary input plugs 5, 6 of the module 4 can be inserted into the sockets 23, 24, respectively, and the output socket 7 of the module 4 can be coupled to the plug 27 on the equipment 26. In normal use, the application can be replicated for multiple pieces of equipment installed in the rack 25. In operation, the equipment 26 can receive power from the main wiring board 21 through the main input line 1 and the output line 3. When an interruption of the voltage on the main wiring board 21 occurs, the automatic transfer switch 50 can then couple the equipment 26 to the auxiliary wiring board 22 through the auxiliary input line 2 and the output line 3. In this manner, power redundancy is provided for the equipment 26 .

[0053] The automatic transfer switch 50 may be particularly useful in high density applications where the rack 25 may contain forty or more pieces of equipment. For example, in this case, forty automatic transfer switches 50 may be required with eighty input plugs 5, 6 and forty output receptacles 7. Typically, such a density requires careful attention to wire management to prevent airflow blockages that could inhibit cooling of the equipment installed in the rack 25. Thus, in such applications, the automatic transfer switch 50 reduces this problem by including wires of a length appropriate for the particular application.

[0054] Various form factors (sizes and shapes) of ATS units are described below. In end and side views, the module 4 is shown to be substantially rectangular in shape, with one of the output line 3 and the input line 2 attached to one end of the module 4 and the other input line 1 attached to the opposite end. Moreover, the cross-sectional area of ​​the module 4 can be less than about 3 square inches (with each axis not exceeding about 1.75 inches), and more preferably, less than about 2 square inches, and the length of the module 4 can be less than 5 inches, with the total volume contained within the module 4 being less than 10 cubic inches, and more preferably, less than about 7 cubic inches.

[0055] A notable feature of this embodiment of the automatic transfer switch 50 is that the relay 12 does not require any additional control circuitry to operate. The absence of relay control circuitry allows the automatic transfer switch functionality to be contained in a much smaller space than would be required for a switch with complex circuitry (e.g., high-speed controllers, optical isolators, current sensors, synchronization circuits, etc.). The use of a DPDT relay (or a matched plurality of relays) to ensure a break-before-make connection prevents connecting two power sources in parallel, which would cause damage to the equipment. The automatic transfer switch 50 utilizes the inherent energy storage capabilities of the most common EDP equipment to operate the equipment during the short time interval (e.g., a few milliseconds) between disconnecting a connection from one source and closing a connection to another source. In this way, the automatic transfer switch 50 provides automatic transfer functionality in a smaller space and at a lower cost than conventional automatic transfer switches.

[0056] Automatic transfer switch 50 also just provides switching power supply at the input end of equipment, thereby minimizes the probability of failure between switch and equipment. In addition, automatic transfer switch 50 occupies relatively small space, and it provides better cable management in the equipment of rack installation. The length of line can allow module 4 to be placed adjacent to the rear panel of each equipment, and can allow to be connected to the patch panel without excessive line length. This configuration eliminates the tangled power lines usually associated with the equipment of rack installation. Although automatic transfer switch is shown as being positioned between a piece of equipment and the patch panel or other power supply receiver, it should be appreciated that automatic transfer switch can be alternatively or additionally located at other positions in the power distribution topology. For example, the switch can be located in a standard duplex receiver, in a dual power supply plug board, in the upstream of a pair of single power supply plug board, in a unified power distribution (UPD) module, in the upstream of a pair of UPD modules or otherwise related to the leaf, branch or root of the power distribution system topology. Additionally, the switch can be used in conjunction with an interleaved UPD module as described in PCT Application PCT / US2009 / 038427 entitled "Power Distribution Systems and Methodology," which claims priority to U.S. Provisional Application 61 / 039,716, both of which are incorporated herein by reference, to provide further options for avoiding power delivery interruptions. Some advantages of the direct-line surge control method are listed below. See Figure 3-6 for some example examples showing details of where circuits may be used in the context of a micro-ATS implemented between equipment and a plug strip.

[0057] 1. Surge Circuit – Sample circuit design, nicknamed “ZCrush”, at Figure 1 - can be placed anywhere needed in the power topology using a variety of forms.

[0058] a. As an additional power line or power module (the surge circuit is placed in a metal or plastic molded housing that is shaped as required by the application and is as small as possible; it can be connected inline via a connector, (one or more) hardwired connection or plug and receptor or any combination of these components required by the application) placed at the required location in the power path. This is a convenient implementation to retrofit existing ATS deployments.

[0059] b. As one or two input power lines to the ATS unit. For units with input acceptors, this is a convenient implementation to retrofit into existing ATS deployments.

[0060] c. As the output power line of the ATS unit.

[0061] d. As a connecting power line between the ATS unit with the output receptor and the device being powered. The Zonit locking power line technology incorporated by reference above makes many of these options easy to implement in a safe manner.

[0062] 2. It can be integrated into strain relief equipment, such as the Zonit Micro ATS "Y" line model strain relief.

[0063] 3. It can be integrated into the case of small form factor ATS units, such as Zonit Micro ATS or Zonit Mini-ATS in any mini-ATS instance.

[0064] 4. It can be used anywhere in the power path where high transient current and / or voltage events need to be controlled. Its small form factor makes it easier to use as an integrated solution (in the device housing) or external solution (outside the housing) compared to larger, bulkier traditional solutions. This is a key advantage, as traditional approaches do not fit into the required space.

[0065] 5. It can be integrated into the circuitry of the ATS by adding a transient surge circuit to the design of the ATS. This can be accomplished by adding it to the existing PCB layout, or it can be accomplished by implementing it as a separate daughter board that is connected and mounted as needed for the specific application. The latter approach may be desirable because it has minimal impact on regulatory agencies (such as Underwriters Laboratory certification).

[0066] In another example, the ATS can be designed to be less susceptible to transient current and / or voltage surges. An example design is shown in the incorporated document mentioned above. This design combines the use of relays and silicon switching methods to eliminate the problems described in the incorporated document.

[0067] Figure 2 The surge suppression circuitry of the power supply limits the current experienced at the contact surface, even in the surge scenarios described above. This can be achieved by limiting the voltage experienced at the contact surface (e.g., by controlling the voltage or relative voltage on one or both power lines) or by ensuring sufficient impedance during critical time periods. Figure 2 The circuit ensures that there is a resistor to limit the peak current during the critical time.

[0068] Figure 3-6 Various form factors of surge suppression circuits according to the present invention that may be used in conjunction with an ATS or other vulnerable equipment are shown. Figure 3An ATS system 300 with an integrated direct-discharge surge suppression circuit is shown. Specifically, the system 300 includes a main power line terminated in a line cap 302 for receiving power from a main power source and an auxiliary power line terminated in a line cap 304 for receiving power from an auxiliary power source. The system 300 also includes an output terminal 306 for connecting to an output load (such as a piece of equipment). In the example shown, the output terminal 306 is a female socket so that the system 300 can be directly connected to the male power port of a piece of equipment. The system 300 also includes a micro ATS module 308, which operates to sense a power interruption or degradation of the signal quality of the power signal of at least the main power source, and in response, switches the power supply from the main power source to the auxiliary power source. The surge suppression circuit 310 is inserted in the auxiliary power line between the module 308 and the line cap 304.

[0069] Figure 4 Shown with Figure 3 The ATS system 400 is similar to the system of in that it includes a main power line terminated in a line cap 402, an auxiliary power line terminated in a line cap 404, and an output terminal 406 that can be directly connected to a piece of equipment. Figure 4 In an embodiment of the present invention, the micro ATS module and the surge suppression circuit are provided within the housing 408. The surge suppression circuit can be operated to suppress surges on the main power line, the auxiliary power line, or both. Alternatively, the surge suppression circuit can suppress surges on the output circuit.

[0070] Figure 5 The ATS system 500 with Figure 4 504, an auxiliary power line terminated in a line cap 504, an output 506, and a housing 508 incorporating a micro ATS module and surge suppression circuit as described above. However, the output 506 is connected to the housing 508 via a power line so that the housing 508 is not directly connected to a power port of a piece of equipment.

[0071] Figure 6 A stand-alone surge suppression power line system 600 in accordance with the present invention is shown. The system 600 includes a power line having a first wire cap 602 at a first end thereof and a second wire cap 604 at a second end thereof. For example, the first wire cap 602 may include a female receptacle for connecting to an input of an ATS or another piece of equipment, and the second wire cap 604 may include a male plug for connecting to a plug strip or other power source. A surge suppression circuit 606 is inserted inline onto the power line between the first wire cap 602 and the second wire cap 604. The system 600 may thus be used in a variety of contexts, including as an aftermarket product to protect an ATS (e.g., by connecting to either or both inputs of the ATS or to an output of the ATS) or another vulnerable device.

[0072] Fig.13 A very basic diagram of a transfer switch 1300 is shown, in conjunction with which surge suppression may be used as described below. Fig.13 The reference numerals are in Figure 14-19 1300. The internal relay 1302 is shown connected to the A position. The output is connected to a load 1304 having a capacitor 1306 across the hot lead of the output of the ATS 1300. Normal transfer may cause the energy stored in the capacitor 1306 to be discharged at the moment the contacts connect to the B-side relay contacts. When disconnection occurs from the A side, these contacts will have a voltage that may be opposite to the voltage stored in the capacitor 1306.

[0073] Figure 11-12 The relationship between these voltages and the possible impact on the output current that the relay must conduct is shown. The current "spike" shown at time t2 is the result of the remaining positive capacitor charge from time t1 (when the AC voltage becomes disconnected from the input terminals). In this example, it is shown that due to the very small load resistance, the capacitors are not significantly discharged. This can be true for a variety of reasons. In particular, the internal capacitance of the load power supply can have large energy storage capacitors that are only charged at the very peak of the AC cycle. The remainder of the AC cycle is always at a voltage lower than the voltage stored in the internal storage capacitors of the power supply. This does not leave a path for the energy stored in the capacitors of the external line connection to discharge, so the voltage and the energy stored thereby remain until the connection of the ATS to the power line occurs.

[0074] refer to Figure 14-16 To prevent the current from becoming too high, or reaching a level that would cause the contacts of an ATS-based relay to become welded together, a simple surge suppression circuit 1400 or inrush limiter is used in applications where the inrush limiter is internally connected to the ATS 1300. Fig.14 The ATS 1300 is shown with the circuit 1400 in normal operation. As shown, current flows through the ATS relay 1302 to the load 1304 and back.

[0075] When the A-side power fails, the ATS starts by disconnecting the power from the A-side source and moving the relay to the opposite input (i.e., the B-side power source), as shown in Figure 1. Fig.15 At this point, the relay 1402 shown in the inrush limiter circuit 1400 is currently open. It is a normally open relay, or a so-called Form A relay.

[0076] Fig.15The current path through the ATS 1302 to the load 1304 is shown shortly after the transfer is completed. It is noted that a resistor 1404 is in series with the power path located inside the inrush limiter circuit 1400. This resistance is generally very small, about 4 to 10 ohms. But it is sufficient to limit the peak current from the discharge capacity 1306 located in the load 1304, as shown. For example, on a 120VAC circuit, the possible peak voltage is about 170 volts. If the AC sine wave is exactly opposite when the transfer is completed, then the peak voltage at this time can be -170 volts, and when added to the remaining voltage stored in the capacitor (up to +170 volts), the difference is 340 volts. Therefore, if a 10 ohm resistor is in series with this, the peak current is limited to 34 amps. Various resistors can be used for specific applications, but in the case of the Zonit uATS product, we use a 10 ohm resistor for the 15 amp and lower products.

[0077] Fig.16 The inrush limiter driver circuit 1400 is shown to have completed the approximately 30 millisecond power delay to the inrush limiter relay 1402 and has released the relay 1402. Current now returns to flow through the contacts of the inrush limiter relay 1402 instead of through the resistor 1404. This saves energy and delivers full voltage to the load 1304.

[0078] Zonit uATS products always return power from side B to side A at the zero voltage crossing point of the AC cycle. See the description of the Zonit uATS in the incorporated case for clarification. Because the transfer from side B to side A occurs at the zero crossing, the energy stored in the capacitor is not dissipated when the contacts connect the side A power supply to the load, and therefore no excessive current will occur.

[0079] Figure 17-19 shows a case where the inrush limiter is internally connected to the ATS housing (see Figure 4-5 ) application. Fig.17 An ATS is shown with an internal circuit 1700 in normal operation. As shown, current flows through the ATS relay 1302 to the load 1304 and back. It returns through the normally closed (NC) additional relay 1702. Resistor 1704 is shown as a contact across that relay contact, but it does nothing because all current bypasses resistor 1304 through the contacts.

[0080] When the A-side power fails, the ATS begins by disconnecting power from the A-side source and moving relay 1302 to the opposite input (i.e., the B-side power source). At this point, the relay 1702 shown in the inrush limiter section on the output of the transfer relay is currently closed. It is a normally closed relay, or what is called a Form B relay. At the moment power is sent to the ATS relay to begin transferring to the B-side, power is also sent to the inrush limiter relay at the output of the transfer relay, causing it to also begin opening.

[0081] Fig.18 The current path to the load through the ATS shortly after the transfer is completed is shown. Note that the resistor 1704 in series with that power path is now conducting power. The relay contacts across the resistor 1704 are opened at the same time as the transfer, so when the power is restored to the load through the ATS contacts, the power must pass through the resistor 1704. This resistance is generally very small, about 4 to 10 ohms. But it is enough to limit the peak current from the discharge capacitor located in the load 1304, as shown in the figure. For example, on a 120VAC circuit, the possible peak voltage is about 170 volts. If the AC sine wave is just the opposite when the transfer is completed, the peak voltage at this time can be -170 volts, and when added with the remaining voltage (up to +170 volts) stored in the capacitor, the difference is 340 volts. Therefore, if a 10 ohm resistor is connected in series with this, the peak current is limited to 34 amperes. Various resistors can be used for specific applications, but in the case of the Zonit uATS product, we use 10 ohm resistors for products under 15 amperes and groups.

[0082] Fig.19 The inrush limiter detector circuit 1700 is shown to have completed approximately 30 milliseconds of power delivery to the inrush limiter relay 1702 and has released the relay 1702. Current now returns through the contacts of the inrush limiter relay 1702 instead of flowing through the resistor 1704. This saves energy and delivers full voltage to the load.

[0083] Zonit uATS products always return power from the B side to the A side at the zero voltage crossing point of the AC cycle. See the description of the Zonit uATS for clarification. Some products (such as the Zonit uATS Industrial) do not necessarily return power to the A side at the zero crossing. Therefore, an inrush limiting function may be necessary during this half cycle. Since the inrush limiter relay is driven by any transfer of the main ATS relay, the 30 millisecond power routing through the resistor also occurs when the main ATS relay releases to restore power to the A side.

[0084] Figures 7A-7C is shown with Figure 6A photograph of a power line with a similar direct-current surge suppression circuit is shown in FIG. In particular, Fig. 7A A perspective view of a power line is shown with an in-line surge suppression circuit housing mounted thereon. Figure 7B A close-up of a direct-current surge suppression circuit is shown with a portion of the housing removed. A ruler is also shown in the photo to provide an indication of the size of the housing. In this case, the housing has a maximum dimension of approximately 55 mm. Figure 7C Close-up of a DC surge suppression circuit with a portion of the housing removed (with Figure 7B DC surge suppression circuit relative).

[0085] According to another aspect of the invention, relays used in relay-based ATSs can be designed and / or adjusted to reduce their vulnerability to transient current and / or voltage surges and the resulting possibility of micro-welding. Relay adjustment can be performed before the relays are installed during ATS manufacturing, or can be performed on relays of already manufactured ATS units, which facilitates the application of processes in the art or as a remanufacturing process. The adjustment process can cause the relay's resistance to point micro-welding to increase significantly, allowing it to reliably tolerate 2 times or more transient current and / or voltage events. An example is that for a general-purpose 2GRL relay used in, for example, a data center environment, the point micro-welding resistance can be increased from approximately 1 microfarad of capacitor discharge to 2 microfarads of capacitor discharge.

[0086] In order to adjust the relay, a device is provided. Fig. 9 An example relay conditioning device is shown in . This device applies a specific surge signal, which can be programmed to condition the relay as needed. These surge currents form arcs across the relay contacts and cause changes in the topology and condition of the relay contacts. These changes increase the resistance of the relay to the micro-weld point when exposed to high transient current and / or voltage events. The changes to the relay contacts can be described as follows. General relays are made with optimized contact materials and shapes to give both high actuation count service life and low resistance when the contacts are closed and in contact. Sufficient resistance to arcing and contact welding is also part of the design process, but is usually only considered in relation to reasonable current and / or voltage limits that are considered appropriate for the intended application. Typically, the shape of the contacts is a segment of a large radius sphere. Imagine two very large beach balls in contact. This means that the contacts touch each other at a single point. After sufficient use, this point will flatten slightly into a small flat area due to the mechanical deformation of the contacts hitting each other when closed. If arcing occurs, the flat area will appear pitted and somewhat irregular depending on the use history.

[0087] When contacts are new, they are usually most susceptible to micro-welding. This can be understood by thinking about how lightning strikes the earth. If there is a high point, then lightning will usually tend to strike that point in that place. This is because that is the shortest path through a mostly uniform insulator (i.e., air). If the area where lightning strikes has several points of equal height, then it will often split into multiple paths and hit multiple points before hitting the ground. This reduces the maximum energy experienced by each point. This is exactly what happens when a universal relay goes through the conditioning process. Figures 8A-8C Shows unused relay contacts ( Fig. 8A ), the relay contacts after 10 relay adjustment cycles on the device ( Figure 8B ), and the relay contacts after 100 relay adjustment cycles on the device ( Figure 8C ). The effect is to increase the number of points on the contacts that are very close in height, which then spreads the arc between those points and reduces the current density at any given point, in a manner similar to what occurs with lightning arcs as described above. Thus, in this case both the shape (flattened) and the texture (roughened) are modified by the electromechanical conditioning process. This conditioning does reduce the effective life of the relay to some extent, but for ATS purposes, especially in a data center where power quality is controlled, the reduction is not significant. This is because the number of ATS cycles is typically very small. A typical data center only requires 3-24 maintenance cycles per year for the ATS to be transferred. ATS units will generally wear out from other electrical component failures before the relay fails. General purpose relays are typically rated for 100k cycles, which indicates that in a typical data center or many other types of use, it will not be the first component to fail, even if its useful life is significantly shortened by the relay conditioning process.

[0088] It is possible to manufacture relays with contact shapes that are more resistant to micro welding and arcing. This can be achieved by shaping the contact area designed for touch into a flat platform with a collection of high points of equal height. This can be done during the manufacture of the contacts, or by stamping the contacts into the desired shape after being manufactured into a universal spherical shape. The contact materials and plating can also be optimized to increase resistance to micro welding. The various methods described in the present invention allow the manufacturer of the contact and / or OEM ATS or other equipment manufacturer to optimize the cost and contact characteristics to match the requirements of the intended application, while allowing the contacts to be manufactured and purchased economically. For example, due to insufficient volume, Zonit adjusts general relays because customized contacts would be much more expensive.

[0089] Fig. 9 A method for implementing a relay regulation circuit is shown. Figures 10A-10CA photograph of a relay conditioning circuit is shown. It will be appreciated that any signal source that provides a signal sufficient to produce the desired morphology change may be employed, taking into account the specific design of the contact surface in question and the expected operating environment of the contact surface. The relay conditioning circuit shown and the method of operating the circuit as described below have several particularly noteworthy features related to optionally incrementally increasing the effective conditioning signal and sequencing the relays based on response time.

[0090] If conditioning is achieved by a series of conditioning signal cycles, the contact surface will gradually become more conditioned with each such cycle, e.g. Figures 8A-8C . For applications where the failure rate is low (even under the worst expected surge conditions), the surge signal can simply be applied in a series of cycles, where each surge signal matches the worst condition expected in the art. However, if the failure rate is higher, then applying a signal that matches the worst expected condition can result in an unacceptably high waste rate associated with conditioning. Thus, in such cases, it can be useful to implement the conditioning process as a series of signal cycles of increasing effective power, such that the earlier, lower power signal cycles have a lower probability of micro-welding the surface to the point where it adheres, and thereafter, the higher power signal cycles fully condition the contact surface to enable it to withstand the largest surges that are likely to occur in the art.

[0091] The illustrated conditioning circuit simulates the surge conditions expected in the art associated with a discharge surge from a charged capacitor against an AC signal. In the art, the expected maximum surge condition occurs when the discharge is timed to coincide with a point on the AC signal that is 180° out of phase with the surge voltage, while a discharge event where the AC signal is nearly in phase with the surge voltage will result in a relatively harmless surge.

[0092] In terms of voltage and capacitance, the illustrated regulation circuit adopts a single set of discharge parameters. In the case of a desired progressive increase in the power regulation signal, the regulation circuit can be set to progressively change the timing associated with the AC signal, from a voltage close to the match (considered to be a phase angle of 0 °) to a maximum voltage difference (considered to be a phase angle of 180 °). It will be appreciated that progressive regulation can be implemented with other circuits to apply an appropriate series of signal cycles. Moreover, specific parameters (e.g., surge voltage, capacitance, AC signal voltage, number of cycles, phase difference between cycles) involve details of specific applications and trade-offs (e.g., between optimal regulation and service life degradation). However, it has been found that a surge voltage of 300-400V (e.g., 339V) and a capacitance of 3 microfarads relative to an AC signal of 240V are effective for regulating the ATS relay contact surface for use in a typical data center environment. In the above-mentioned ATS application, a progressive increase in phase angle is considered unnecessary. Therefore, the surge signal is timed to be applied at a 180 ° phase angle and this process (cycle) is repeated, for example, 16 times. For a case where the failure rate is high, for example, the phase angle may be increased from a small phase angle (eg, 30°) to 180° over several cycles, and then performed at the 180° phase angle for multiple cycles.

[0093] An additional feature of the present invention is a method of measuring, grading and grouping contacts based on their transfer time. Common contacts can vary greatly in their actuation time to open or close. This is very important in ATS design, where the movement and sequencing of one or more relays need to be carefully controlled as part of how the ATS operates. There are multiple ways to deal with this problem, some of which are described in other documents incorporated by reference. The present invention adds another way to solve this problem.

[0094] Relay actuation time variations may be too great to accurately control the movement of the relay set to achieve the desired ATS transfer time. Therefore, relay sequencing is a method to allow the ATS to shift quickly enough to meet the expected design requirements at a lower cost. The ATS can be designed so that it does not have to measure and compensate for relay actuation time variations, which saves complexity and expense.

[0095] In one example of the present invention, the relay regulation function can be combined with the measurement of each individual relay actuation time. The relays can then be combined into sets, where each relay in the set is within the required high-low actuation time range. Another device can be provided that sorts the relays to be used in the ATS from the slowest to the fastest actuation speed. Each relay in the set used in an ATS unit can then be installed in a specific position in the ATS unit being built. This is because the ATS can be designed so that the relationship between the members of the set of relays it uses can benefit from this actuation speed sorting. This can also improve relay control accuracy and therefore improve ATS transfer speed and reliability.

[0096] In another example, the relay conditioning function may be performed on a relay already installed in a working ATS unit. In this case, the apparatus is relatively simple, consisting of one or more plug strips and a set of attached capacitors to produce a transient current of the desired value across the contacts of the relay when the connected ATS is transferred. Additional equipment (such as a current interrupter switch controlled by a signal generator that can vary the time between control signals) may be used to automate the test cycle by forcing the connected ATS to automatically switch when power on the preferred side of the ATS is interrupted by the action of the signal generator in combination with the current interrupter switch. The conditioning cycle may be repeated as many times as necessary and / or optimal.

[0097] The foregoing description of the present invention has been presented for the purpose of illustration and description. In addition, this description is not intended to limit the present invention to the form disclosed herein. Therefore, changes and modifications commensurate with the above teachings and the skills and knowledge of the relevant fields are within the scope of the present invention. The embodiments described above are also intended to explain the known best mode of practicing the present invention, and to enable other technical personnel in the art to utilize the present invention in such or other embodiments, and to have various modifications required for the (one or more) specific applications or (one or more) uses of the present invention. The attached claims are intended to be interpreted as including alternative embodiments to the extent permitted by the prior art.

Claims

1. An automatic transfer switch system, comprising: A switch unit having: a first input for receiving a first power signal via a first power line extending between the switching unit and a first power receptacle associated with a first power source; a second input for receiving a second power signal via a second power line extending between the switching unit and a second power outlet associated with a second power source different from the first power source; An output terminal for providing a power signal to a connected load; a switch for selectively connecting one of the first input terminal and the second input terminal to the output terminal based on a power signal state of at least one of the first power signal and the second power signal; as well as A surge suppression circuit for suppressing surges at the switch unit, wherein: The surge suppression circuit is disposed at one of: 1) between the switch unit and one of the first power socket and the second power socket, and 2) between the switch unit and the connected load; and The surge suppression circuit is configured to suppress surges associated with switching of the switching unit between the first power source and the second power source.

2. The switching system of claim 1, wherein each of the first power line and the second power line comprises a first end for connecting to the switching unit and a second end for connecting to one of the first power line and the second power line, and the surge suppression circuit is disposed in-line on one of the first power line and the second power line between the first end and the second end.

3. The switching system of claim 1, wherein the switching unit is configured such that the first power source is a main power source of the switching unit, and the surge suppression circuit is disposed between the switching unit and the second power socket.

4. The switching system of claim 1, wherein at least one of the first power receptacle and the second power receptacle is a receptacle of a power strip.

5. A switching system as described in claim 1, wherein in response to detecting one of a power interruption and a degradation of the first power signal from the first power source, the switching unit operates to switch from a first state in which the first input terminal is connected to the output terminal and a second state in which the second input terminal is connected to the output terminal.

6. The switch system of claim 1, wherein the switch comprises a first electromechanical relay.

7. The switch system of claim 1, wherein the switch comprises a solid-state switch.

8. The switch system of claim 1, wherein the switch unit and the surge suppression circuit are disposed within a switch housing of the switch unit.

9. A method for manufacturing an automatic transfer switch, comprising: Provide automatic transfer switch system, including: 1) a switch unit having a first input terminal for receiving a first power signal via a first power line extending between the switch unit and a first power socket associated with a first power source, a second input terminal for receiving a second power signal via a second power line extending between the switch unit and a second power socket associated with a second power source different from the first power source, an output terminal for providing a power signal to a connected load, and a switch for selectively connecting one of the first input terminal and the second input terminal to the output terminal according to a power signal state of at least one of the first power signal and the second power signal; and 2) a surge suppression circuit for suppressing surges at the switch unit: the surge suppression circuit is disposed at one of: 1) between the switch unit and one of the first power outlet and the second power outlet, and 2) between the switch unit and the connected load, wherein the switch unit includes an electromechanical relay having a contact surface for making electrical contact between an armature of the electromechanical relay and a connected circuit; and applying an electrical signal to the contact surface; and A surge associated with the switching unit switching between the first power source and the second power source is suppressed.

10. The method of claim 9, wherein each of the first power line and the second power line comprises a first end for connecting to the switch unit and a second end for connecting to one of the first power line and the second power line, and the method further comprises: The surge suppression circuit is disposed inline on one of the first power line and the second power line between the first end and the second end.

11. The method of claim 9, wherein the switch unit is configured such that the first power source is a main power source of the switch unit, and the method further comprises: The surge suppression circuit is disposed between the switch unit and the second power socket.

12. The method of claim 9, wherein at least one of the first power receptacle and the second power receptacle is a receptacle of a power strip.

13. The method of claim 9, wherein in response to detecting one of a power interruption and a degradation of the first power signal from the first power source, the switch unit operates to switch from a first state in which the first input terminal is connected to the output terminal and a second state in which the second input terminal is connected to the output terminal.

14. The method of claim 9, wherein the switch comprises a first electromechanical relay.

15. The method of claim 9, wherein the switch comprises a solid state switch.

16. The method of claim 9, wherein the switch unit and the surge suppression circuit are disposed within a switch housing of the switch unit.

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