Residual current monitoring for each outlet of the power distribution unit

Abstract

A power distribution system and method in which a power distribution unit (PDU) is provided with residual current monitoring at a plurality of outlets of an outlet module within the PDU. The residual current monitoring circuit of the PDU includes at least one current sensor associated with an outlet of the PDU to detect the residual current of each of the outlets. A method for detecting residual current in a PDU having a plurality of power outlets includes detecting a current leakage at each outlet as a difference between a supply current and a return current of each outlet.

Description

Technical Field

[0001]

[0001] This disclosure generally relates to a power distribution unit configured to reduce electrical hazards. More specifically, this disclosure relates to a power distribution unit that provides residual current monitoring at an electrical outlet of the power distribution unit.

Background Art

[0002]

[0002] A conventional power distribution unit (PDU) is an assembly of electrical outlets (also called receptacles) that receives power from a power source and distributes that power to one or more separate electronic products. Each such PDU assembly has a power input that receives power from one or more power sources via a power cord of the PDU. The electrical outlets can be used to supply power to one or more electronic products plugged into the PDU outlets. PDUs are used in many applications and settings, such as within or on top of an electronics rack.

[0003]

[0003] The general use of a PDU is to supply operating power to electrical equipment within computing facilities such as enterprise data centers, multi-tenant hosting environments like colocation facilities, cloud computing, and other data center types. Such computing equipment may include an electronic equipment rack having a rectangular or box-shaped housing, sometimes called a cabinet or rack, and associated components for assembling equipment, associated communication cables, and associated power distribution cables. Electronic equipment may be assembled within such a rack, and as a result, various electronic devices (e.g., network switches, routers, and servers, etc.) are assembled vertically stacked within the rack. One or more PDUs may be used to supply power to the electronic equipment. A plurality of racks, each enclosing a number of electronic components and having associated component wiring positioned both inside and outside the area occupied by the rack, may be oriented side by side. Such racks generally support equipment used in an enterprise computing network, often called an enterprise network. Enterprise data centers, multi-tenant hosting environments like colocation facilities, cloud computing, and other data center types are often very important to business operations. Therefore, it is important that the electrical connections between the PDU and the servers, storage, and network equipment associated with the PDU are secure in order to maintain the uptime of the equipment to reliably support enterprise users.

[0004]

[0004] Because data centers rely on high-voltage power distribution, if an electrical fault occurs when any of the safety features designed into the power distribution system are compromised, operators and maintenance personnel are at risk of serious injury. One such safety feature is the insulator surrounding the dangerous voltage conductor. If this insulator is damaged by aging, mechanical stress, or damage during installation, it can pose a lethal danger to personnel working in and around this wiring. In addition, electrical infrastructure components and IT loads attached to the distribution system have components that can provide an electrical path for leakage current that has a fault and can be dangerous if a person physically contacts these devices.

[0005]

[0005] For these reasons, the industry demands the ability to identify in advance the risk of physical harm to workers in these facilities due to potential residual current or leakage. One example is the operation of electrical equipment in the industry standard DIN VDE 0105-100 VDE 0105-100:2015-10. This standard defines the need for regular insulation measurements of the power distribution system to identify the causes of insulation breakdown. This typically requires the removal of power to a portion of the power distribution chain, which allows these isolation measurements to be performed. This can be a very problematic issue in data centers where uptime is extremely important and shutdowns are very costly.

[0006]

[0006] To minimize this impact on mission-critical and highly reliable systems and facilities, this standard allows the inspection interval to be extended if continuous monitoring of the residual current is performed and the ability to give an alarm when an increase in the leakage current is detected. Therefore, the demand for continuous monitoring and alarming of the residual current in rack PDUs continues to increase. In addition, continuous residual current monitoring (RCM) is becoming an increasingly essential function within certain jurisdictions.

[0007]

[0007] Current methods for implementing RCM are costly, and this monitoring is limited to the power cords of PDUs assembled on the rack. A typical three-phase power cord capable of supplying 22 KVA (or more) to IT loads connected to the rack PDU can support a fairly large number of IT loads (e.g., 48 or more) by a single power cord. Currently, the main solution available for residual current monitoring (RCM) is at the power cord inlet to the PDU. One example is from Bender, Inc., which is published in its product overview Residual current monitoring (January 2021), where the line conductor and neutral conductor of the power cord are first routed through a high-sensitivity current transformer and then routed to the IT load attached to the rack PDU receptacle. In the normal operating state, all the current flowing from the line conductor must be equal to the current returning through the neutral conductor, so there will be no current in the secondary winding of the RCM current transformer. Any current detected on the secondary side of the RCM transformer represents the amount of leakage current flowing from the line conductor to the protective ground rather than through the neutral conductor. This leakage current path is dangerous for personnel physically contacting the equipment where this leakage current exists.

[0008]

[0008] In another known example of RCM, the neutral from the three-phase conductors and the three-phase input power cord passes through a toroidal RCM current transformer (CT). Then, the wire from the transformer is connected to an electrical measurement board that converts the transformer secondary current output to a voltage, and the voltage is digitized by an A / D converter on a microcontroller included on a printed circuit board within the PDU. An additional wire wound around the core of the transformer enables demagnetization of the current transformer to remove any residual magnetic field. This can occur after a high-current fault event occurs downstream of the PDU.

[0009]

[0009] Using any of these known RCM implementation forms, the end user can only determine that there is a fault downstream of the input power cord of the rack PDU that is generating excessive residual current. None of these RCM implementation forms provide any additional fault isolation information that can assist personnel in determining whether there is a fault in one or more IT loads or whether there is a fault in the rack PDU. Therefore, monitoring at the input cord meets the continuous monitoring of residual current requirements but does not provide the ability to quickly identify the location of the IT equipment, i.e., a specific outlet of the PDU, that is causing the excessive leakage current. This can lead to excessive downtime when attempting to identify and repair the faulty IT equipment.

[0010]

[0010] In other RCM technologies, additional residual current sensors are provided to sense each phase of the three-phase power cord and at least identify where the faulty equipment is generally located. For example, in one known RCM configuration, up to six RCM sensors are attached to each power branch present within the rack PDU. This solution helps to further isolate residual current faults or leaks down to the branch or aggregation of outlets. There are mainly two types of known RCM sensors included within the rack PDU. i) Type A is used to monitor AC current in the range of 42 - 2000 Hz (compliant with the International Electrotechnical Commission standard IEC-60755), and ii) Type B is used (compliant with IEC-60755) to measure AC current (up to 2000 Hz) as well as pulsating and smoothed DC current. Type B RCM monitoring can detect DC leakage current (both smoothed and pulsating) in addition to AC leakage current. Type B can be useful for PDU applications that use switch-mode power supply technology for high-end servers and IT equipment, which can be susceptible to faults due to insulation breakdown leading to DC leakage current. Nevertheless, while branch-by-branch residual current monitoring is available, this RCM technology still does not provide the ability to quickly identify the location of the outlet of the attached IT equipment that is causing the excessive leakage current.

[0011] U.S. Patent No. 8,694,272 and U.S. Patent No. 8,305,737 each disclose and describe a rack PDU having a power sensing and monitoring system that includes a single current transformer (CT) for each receptacle or outlet to measure current on the power supply line pins of the receptacle. Power sensing and monitoring can be used to provide power-related information to entities that supply, deliver, and consume power. In particular, U.S. Patent No. 8,694,272 describes a PDU having a monitoring system that monitors the power consumption at each outlet of the PDU, i.e., "Power-On-Per-Port Sensing" (POPS). However, none of these patent documents show or describe residual current monitoring. U.S. Patent No. 8,907,678 shows and describes an apparatus and method for monitoring current leakage from an AC power source to an IT device, such as a PDU within a data center, but does not provide for identifying the specific outlet and connected power source of the current leakage.

[0012]

[0012] Accordingly, there is still a need for a system and method that monitors residual current at each outlet within a PDU to provide additional fault isolation information to maintenance personnel, enabling the maintenance personnel to identify and correct a fault condition and restore affected IT equipment while minimizing the impact on the system uptime.

Summary of the Invention

[0013]

[0013] A system and method are provided for monitoring the residual current of a PDU at the outlet level. A preferred embodiment of the PDU provides enhanced information to IT and facility personnel in a data center to more easily identify IT equipment that has (or is having) a fault exhibiting an increase in residual current leakage. A preferred embodiment of the residual current monitoring circuit used in the PDU includes two current sensors associated with the outlets of the PDU to detect the difference in current between the line current supplied to the outlet and the return current from the outlet. Accordingly, a preferred method provides for residual current detection in a power distribution unit having a plurality of power outlets, and for detecting current leakage at each outlet as the difference between the supply current and the return current of each outlet among the plurality of outlets.

[0014]

[0014] A preferred embodiment of the power distribution unit includes a power distribution unit housing and a power source disposed within the housing having a plurality of input conductors. The PDU includes a plurality of outlets disposed within the housing, each of the plurality of outlets having a plurality of connectors including a first connector electrically connected to one input conductor and at least a second connector electrically connected to a different input conductor. Each outlet has an associated residual current monitoring circuit having at least a current sensor associated with the first and second connectors to determine the residual current of each of the outlets.

[0015]

[0015] One preferred embodiment of the power distribution unit includes a power distribution unit housing and a power source disposed within the housing having a plurality of input conductors. The PDU includes a plurality of outlets disposed within the housing, each of the plurality of outlets having a plurality of connectors including a first connector electrically connected to one input conductor and at least a second connector electrically connected to a different input conductor. Each outlet has a residual current monitoring circuit having a first current sensor associated with the first connector to define a first current sense output and a second current sensor associated with at least the second connector to define a second current sense output. A preferred PDU includes a differential detector coupled to the associated residual current monitoring circuit of each outlet to determine the current difference between the first current sense output and the second sense output of each outlet.

[0016]

[0016] A preferred embodiment of the outlet module includes at least one circuit board, a first pair of current sensors assembled to the at least one circuit board, at least a second pair of current sensors assembled to the at least one circuit board, at least one differential detector assembled to the at least one circuit board to determine the difference between the current sense outputs of each pair of current sensors, a first power outlet associated with the first pair of current sensors, and at least a second power outlet associated with the at least second pair of current sensors.

Brief Description of the Drawings

[0017]

[0017] A further understanding of the nature and advantages of the present technology can be realized by referring to the following drawings. In the accompanying drawings, like components or features may have the same reference label.

[0018]

Figure 1

[0018] FIG. 1 is a diagram of a preferred embodiment of a power distribution unit (PDU).

[0019]

Figure 2

[0019] Figure 2 is a partial block wiring diagram of the PDU of FIG. 1 connected to a power input and a network.

[0020]

Figure 3

[0020] Figure 3 is a block diagram of one preferred embodiment of a receptacle module for use in the PDU of FIG. 1.

[0021]

Figure 4

[0021] Figure 4 is a block diagram of another preferred embodiment of a receptacle module for use in the PDU of FIG. 1.

[0022]

Figure 5

[0022] Figure 5 is a block diagram of yet another preferred embodiment of a receptacle module for use in the PDU of FIG. 1.

[0023]

Figure 6

[0023] Figure 6 is an exploded perspective view of one of the receptacles for use in the receptacle modules of FIGS. 3 - 5.

Figure 7

[0023] Figure 7 is another exploded perspective view of the receptacle for use in the receptacle modules of FIGS. 3 - 5.

[0024]

Figure 8

[0024] Figure 8 is an exploded perspective view of one preferred embodiment of a receptacle module for use in the PDU of FIG. 1.

Figure 9

[0024] Figure 9 is another exploded perspective view of a preferred embodiment of a receptacle module for use in the PDU of FIG. 1.

[0025]

Figure 10

[0025] Figure 10 is a perspective view of the receptacle module of FIGS. 8 - 9.

[0026]

Figure 11

[0026] FIG. 11 is a cross-sectional view of the outlet module of FIG. 10.

[0027]

Figure 11A

[0027] FIG. 11A is a schematic view of an alternative embodiment of the outlet module for use in the PDU of FIG. 1.

Figure 11B

[0027] FIG. 11B is a schematic view of an alternative embodiment of the outlet module for use in the PDU of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0028]

[0028] This description provides examples and is not intended to unnecessarily limit the scope, applicability, or configuration of the present invention. Rather, the following description provides a possible explanation for those skilled in the art to implement the embodiments of the present invention. Various changes may be made to the functions and arrangements of the elements. Therefore, various embodiments may be subject to omissions, substitutions, and / or additions of various procedures or components as necessary. For example, the aspects and elements described with respect to a particular embodiment may be combined in various other embodiments. It should also be understood that the following systems, devices, and components may be components of a larger system, either individually or collectively, and that other procedures may take precedence over their application or may modify their application in some cases.

[0029]

[0029] Exemplary preferred embodiments of a power distribution unit (PDU) are described herein. The present disclosure provides exemplary embodiments having the ability to determine residual or current leakage at each outlet of a PDU. Preferred PDUs having multiple outlets and a method for monitoring residual current for each outlet facilitate the efficient determination of the source of leakage current. This knowledge can minimize downtime in a data center and / or minimize or eliminate electrical hazards to personnel.

[0030]

[0030] FIG. 1 shows an exemplary embodiment of a PDU 10 that includes a housing 12 with a plurality of outlets 20 (also referred to as “receptacles” or “outputs”) assembled therein for supplying power to individual assets or devices, such as assets used in the operation of a data center. The assets may be assembled within an equipment rack and suitably plugged into one of the outlets 20 of the PDU. Thus, the PDU 10 can be configured to be assembled vertically or horizontally. For supplying and distributing power to the connected assets via the outlets 20, the PDU 10 is configured to receive a power input internally. As shown, the PDU may include an internal wiring input power cord 30 that extends externally and terminates with an associated plug 32 for connection to a power source in a conventional plug and receptacle connection. Alternatively, the PDU 10 can be configured to be internally wired to an external power source. The PDU 10 may include a visual display portion 40 for displaying monitored information, such as an indication of which outlets of the PDU detected a current leak. The visual display can display other information, such as power consumption, voltage, and / or current for each outlet, for example. Alternatively or additionally, the PDU 10 can be coupled to an external display for communicating such information. The outlets 20 can be grouped and configured to define one or more outlet modules 200 as described herein. For example, each outlet module 200 of the illustrated PDU 10 preferably includes six outlets 20a - 20f. However, it should be understood that the preferred embodiment of the outlet module 200 can include fewer or more outlets 20, provided that at least one outlet, preferably two or more outlets, are configured with residual current monitoring in the manner described herein.

[0031]

[0031] The block diagram of FIG. 2 shows an exemplary system 2 including a preferred PDU 10 for supplying power to one or more associated computing assets, such as devices of a computing network 4. The PDU 10 can communicate via the computer network 4 with a data center operator who uses a workstation or other device connected to the network 4 and used for data center management or other enterprise management, or a network application such as a power manager application 6. As schematically shown, the preferred receptacle module 200 of the PDU 10 is wired and configured with a residual current monitoring (RCM) circuit 100 that detects or determines the residual current or leakage of each receptacle 20a-20n of the module 100. Thus, the preferred embodiment of the PDU 10 is configured to provide residual current monitoring "per receptacle". Generally, each receptacle has an associated RCM circuit 100, and the associated RCM circuit 100 preferably includes a first current sensor 100a and a second current sensor 100b in combination with a differential detector 110. In an AC environment, the first current sensor 100a and the second current sensor 100b may also be used to alternately determine the current supplied to and returning through the associated receptacle 20. Each sensor 100a, 100b generates or defines a current sense output indicative of the detected current, and the current sense output is provided to the differential detector 110. The differential detector 110 determines whether there is a difference in the current sense outputs of the first and second current sensors 100a, 100b to determine whether there is a residual current or leakage. In the preferred embodiment described herein, the differential detector 110 is embodied as a microcontroller 110. The microcontroller 110 is preferably configured to communicate the detection of the residual current to a display 40 or otherwise communicate the residual current to a network device or operator via the network 4 to address the issue with appropriate personnel.Thus, the PDU 10 preferably includes a network interface card 60 for communicating with devices on the network 4 and may be configured for internal communication between the modules 200 of the PDU 10.

[0032]

[0032] Figures 3 through 5 show block diagrams of a preferred receptacle module 200 and an RCM circuit 100 electrically connected to a power input via an internal power source or power supply 112 of the PDU 10. The power supply 112 includes a plurality of conductors for transmitting single-phase or poly-phase power input to the PDU 10. As shown, each receptacle 20a - 20h of the module 200 has two or more connectors 22 for electrically connecting to two conductors of the power supply 112. Each receptacle 20a - 20h also includes an associated preferred residual current monitoring circuit 100. Each residual current monitoring circuit 100 includes a first current sensor 100a associated with one connector 22a of the receptacle 20 and a second current sensor 100b associated with another connector 22b of the receptacle 20. A preferred differential detector 110 is electrically connected to each current sensor 100a, 100b to receive the respective current sense outputs of the current sensors 100a, 100b for each receptacle 20 within the module 200. The preferred embodiment of the receptacle module described herein can include a voltage sensing resistor network 120 for determining the voltage at each receptacle 20a - 20h along with other power-related parameters described herein. Each receptacle 20a - 20h is also interconnected to the ground GND within the power supply 32, although these connections from the receptacles 20a - 20h are not shown in Figures 3 through 5.

[0033]

[0033] FIG. 3 specifically shows an exemplary embodiment of a preferred module 200 electrically connected to two conductors L1, L2 of a power supply 112. Depending on the configuration of the power supply 112, the first conductor L1 may be connected to the line power within the power supply 112, and the conductor L2 may be connected to the neutral within the power supply 112. Thus, the outlet module 200 may be configured such that each outlet 20 has one connector 22a electrically connected to the first conductor L1 that transmits line power and the other connector 22b electrically connected to the second conductor L2 as the neutral conductor. Alternatively, in a polyphase configuration of the power supply 112, the conductors may be connected to different phases of the power supply 112. Thus, for example, each outlet 20 of the module 200 can have one connector 22a electrically connected to the first conductor L1 that transmits the line power of the first phase and the other connector 22b electrically connected to the second conductor L2 that transmits the line power of the second phase.

[0034]

[0034] In the case of the polyphase power supply 112, the PDU 10 can have either a delta power input configuration or a wye power input configuration, as shown in FIGS. 4 and 5 respectively. As shown in FIG. 4, the power supply 112 is in a delta configuration and is composed of a three-phase power input having a first conductor L1 for transmitting a first phase, a second conductor L2 for transmitting a second phase, and a third conductor L3 for transmitting a third phase. The preferred PDU 10 in FIG. 4 shows three receptacle modules 200a, 200b, 200c having receptacles 20 electrically connected to the conductors L1, L2, L3 in various combinations. More specifically, the receptacle connectors 22a, 22b of the first module 200a are electrically connected to the first and second conductors L1, L2, the receptacle connectors 22a, 22b of the second module 200b are electrically connected to the second and third conductors L2, L3, and the receptacle connectors 22a, 22b of the third module 200c are electrically connected to the first and third conductors L2, L3. Alternatively or additionally, the input power to the power supply can include a neutral wire N. Thus, for example, any conductor 22b having a current sensor 100b for detecting a return current can be electrically connected to a conductor or neutral. Each module 200a, 200b, 200c preferably includes microcontrollers 110a, 110b, 110c for receiving current sense outputs from the respective associated current sensors 100a, 100b of each receptacle 20. Thus, the microcontrollers 110a, 110b, 110c can detect the residual current or leakage of each receptacle 20 of the respective associated modules 200a, 200b, 200c by determining the difference between the currents transmitted within the connectors 22a, 22b of the receptacle 20.

[0035]

[0035] Using a neutral wire, the power input can have either a delta configuration or a Y - shaped configuration. FIG. 5 shows a power supply 112 having a Y - shaped power input. The power supply 112 is shown with four conductors including a first conductor L1 that transmits a first phase, a second conductor L2 that transmits a second phase, a third conductor L3 that transmits a third phase, and a fourth conductor N that is at neutral. Each receptacle 20 within each module is preferably electrically connected to the neutral conductor N for detecting the return current by the secondary current sensor 100b. The receptacles 20a - 20h within the common receptacle module 200 are preferably connected to the common conductors of the input power, and different modules 200a, 200b, 200c are electrically connected to the conductors of the input power of different phases. The preferred PDU10 of FIG. 5 preferably shows the first connectors 22a of the receptacles of three receptacle modules 200a, 200b, 200c electrically connected to the conductors L1, L2, L3 respectively. The current sensor 100a associated with the first connector 22a within each receptacle 20 detects the current supplied to the receptacle. Again, each receptacle module 200a, 200b, 200c preferably includes microcontrollers 110a, 110b, 110c for receiving current sense outputs from the respective associated current sensors 100a, 100b of each receptacle 20a - 20h. Thus, by determining the difference between the currents transmitted within the connectors 22a, 22b of each receptacle, the microcontrollers 110a, 110b, 110c can detect the residual current or leakage of the respective associated modules 200a, 200b, 200c for each receptacle.

[0036]

[0036] Figures 6 through 7 show a perspective view of a preferred outlet assembly 20' that includes two current sensors 100a, 100b for use in residual current monitoring. The outlet 20' generally includes a core body 220, and two or more connectors 222 are fixed within the body and are electrically connected to a power supply conductor to supply power to a device or asset plugged into the outlet 20'. Preferred embodiments of the outlet assembly may be constructed as the combination outlets shown and described in U.S. Patent Application Publication No. 2021 / 0288434, filed on March 16, 2020, U.S. Patent No. 10,249,998, filed on July 13, 2017, and U.S. Patent No. 10,498,096, filed on April 1, 2019, the entire disclosures of which are incorporated herein by reference.

[0037]

[0037] The outlet assembly 20' includes a preferred core body 220 that has an input face side 220a and an opposite base side 220b, with three apertures 220c extending therebetween. The core 220 can be formed, for example, from injection molded plastic having an outer surface configured to mate with one or more connector types. For example, the outer surface of the core 220 can be configured as a C13 outlet that mates with a C14 plug having a rectangular aperture 220c for receiving terminals in a corresponding orientation. Alternatively, the outer surface or apertures 220c of the core can be configured to receive two or more types of plugs, i.e., a "combination outlet," as shown and described in U.S. Patent No. 10,498,096 (incorporated herein by reference), and as exemplified in the three cores of the module 200' of FIG. 8 that have a T-shaped aperture for receiving two types of plugs.

[0038] Referring again to FIGS. 6 and 7, the outlet assembly 20' may include a first power terminal 222a and a second power terminal 222b extending from the base side 220b. The outlet 20 may include a ground terminal 222c defining a third connector for electrically connecting to a ground conductor of a power supply, such as ground conductor GND. The terminals 222a, 222b, 222c may be constructed from a suitable conductive material such as tin, gold, silver, copper, and phosphor bronze. A combination of multiple materials can be used. In one embodiment, the terminals may include a copper alloy having a tin plating. All standard outlet / plug types (e.g., C13, C14, C19, and C20) refer to industry standard connectors defined in the International Electrotechnical Commission (IEC) standard publication IEC60320 as of the filing date of this application. Embodiments are shown and described with respect to C13 / C14 and C19 / C20 outlet / plugs, but other combinations can also be used. Other suitable connector types may include, for example, but not limited to, IEC C2, C4, C6, C8, C10, C12, C16, C16A, C18, C22, C24, or industry standard outlets / plugs such as NEMA 5-10R, 5-15R, 5-20R, 6-20R, 6-30R, 6-50R, L15-20R, L15-30R, L21-20R, L21-30R.

[0039]

[0039] Included in the socket assembly 20' and shown in the exploded views of FIGS. 6 and 7 are preferred embodiments of current sensors 100a, 100b associated with and engaging the first and second terminals 220a, 220b of the socket 20'. The current sensors 100a, 100b can be embodied as toroidal current sense transformers, such as current transformers (CTs) for example. A preferred current transformer (CT) for use is manufactured by Shenke Electronics Co., Ltd in Hebei Province, China, with the part number 1HKW.506.6940.1C. An exemplary CT has a maximum primary operating current of 40 A, a turns ratio of 1:2000, and a load resistance of 10 Ω. In the preferred embodiment shown, the current sensors 100a, 100b are current transformers having output lines including two output leads 102a, 102b. The preferred current transformers (CTs) 100a, 100b are annular, and the power terminals 222a, 222b of the socket 20' extend through the annular openings of the sensors to associate the sensors with the socket 20'. The current sense output from the sensors 100a, 100b is proportional to the magnitude of the current flowing through the conductors or power terminals 222a, 222b associated with the sensors 100a, 100b. In a preferred embodiment of the socket assembly 20', the current sense output of the sensors 100a, 100b can be output on the two output leads 102a, 102b within each sensor across a load resistor. Alternatively or additionally, one or more of the residual current monitoring circuits 100 can include a load resistor and an anti-aliasing filter in addition to the current sensors 100a, 100b and associated microcontrollers.

[0040] Figures 8 through 10 show various exploded views of a preferred module 200' assembled by six outlets 20'a through 20f disposed within a module tray or housing 230 and engaging preferred toroidal current sensors 100a, 100b. The sensors 100a, 100b are preferably assembled by respective output lead wires 102a, 102b assembled to a printed circuit board PCB240. Thus, the two sensors 100a, 100b are disposed between the outlet core 220 and the PCB240, and more preferably between the module housing 230 and the PCB240. Figure 11 shows a cross-sectional view of a preferred outlet module 200'. The module 200' is preferably assembled to fit snugly within the housing 12 of the PDU10, preferably using a pair of sensors positioned within the width W1 of the PCB240 and / or within the width W2 of the module housing 230. In the illustrated preferred embodiment, the current sensors are offset from each other with one sensor 100b assembled closer to the PCB40 than the other current sensor 100a. Further, if the sensors 100a, 100b can be assembled to the PCB240, the sensors 100a, 100b can be partially overlapped with each other. In embodiments where the pair of current sensors 100a, 100b are offset or stacked within the assembly, the total height H of the space between the PCB240 and the housing 230 that houses the sensors 100a, 100b is preferably less than twice (2X) the depth D of the housing 230, and is from 1 to 1 / 2 (1X to 1 - 1 / 2) of the depth D of the housing. Alternatively, the sensors 100a, 100b can be assembled to the PCB240 such that they are in a common plane with each other. The core 220 of each of the outlets 20a through 20e is preferably oriented within the housing 230 such that each face 220a is disposed in a common plane. The preferred module 200' includes one PCB240 for assembling each of the first current sensor 100a and the second current sensor 100b.An alternative embodiment of the module 200' can include at least two printed circuit boards for assembling two current sensors 100a, 100b on different PCBs. As shown, one or more PCBs 240 can be oriented parallel to the common plane of the core surface 220a. Alternatively, as shown by the phantom lines in FIG. 11, one or more PCBs 240' and one or more connectors 222b' can be oriented to position the PCB 240' and the associated and assembled current sensor (not shown) perpendicular to the core surface 220a.

[0041]

[0041] FIGS. 11A and 11B show schematic views of alternative embodiments of a receptacle assembly for use in the aforementioned receptacle module. Generally, each alternative embodiment of the receptacle assembly includes one or more current sensors disposed around one or more power terminals to provide a residual current monitor for the associated receptacle. Specifically, FIG. 11A specifically shows two current sensors 100a, 100b with one sensor disposed around two or more power terminals. As shown, the first current sensor 100a is disposed around the first power terminal 222a of the receptacle assembly 20", senses the current supplied to the receptacle via the terminal 222a, and, unlike the aforementioned embodiment, the second current sensor 100b of the assembly is disposed around both the first and second power terminals 222a, 222b to monitor the residual circuit of the receptacle assembly 20". By incorporating this alternative embodiment of the receptacle assembly 20" into the receptacle module 200, residual current monitoring for each receptacle can be achieved in one or more of the receptacles having one sensor 100a for sensing the supplied current and a separate sensor 100b for monitoring the residual current.

[0042]

[0042] FIG. 11B shows another alternative embodiment of the outlet assembly 20”’ having a single current sensor 100 disposed around each of the first and second power terminals 222a, 222b for only residual current monitoring rather than current monitoring. Thus, by incorporating this alternative embodiment of the outlet assembly 20”’ into the outlet module 200, residual current monitoring for each outlet can be achieved by, in particular, one or more of the outlets having a single sensor 100 for residual current monitoring.

[0043]

[0043] Referring again to FIG. 11, the power terminals 222a, 222b, 222c can be constructed and assembled within the module 200’ in a manner similar to that shown in U.S. Patent Application Publication No. 2021 / 0288434, which is incorporated by reference. To define a preferred spacing between the module housing 230 and the PCB 240, the second terminal 222b can be disposed to extend on each side or through the PCB 240. Further, one or more of the power terminals 222a, 222c of the outlet can be connected to each other by a common conductor. For example, each of the first conductors 222a in each outlet 20a - 20e has an aperture 226 formed therein such that a common conductor, such as the first conductor L1, can extend therethrough. Similarly, the third conductors 222c of each outlet 20a - 20e can have apertures formed therein for receiving a grounded ground conductor GND’ and connecting the third conductors 222c to each other.

[0044]

[0044] As shown herein, the base side 220b of the core 220 can be configured to be assembled within the module housing 230. The outlets 20a-20e can be spaced equidistant from each other or at different distances from each other. The outlets can also define a gap or space between the core 220 and the inner wall of the housing to accommodate various plug types. The outlets 20a-20e can have a space between adjacent outlet cores 220 that is unobstructed, or there can be walls extending between each outlet. If there is no space or wall between the outlets, the module 200' can be configured with a high-density outlet design as further described in U.S. Patent Nos. 9,614,335 and 9,627,828, each of which is hereby incorporated by reference. The housing 230 can include one or more latch levers 232 that operate or pivot to hold or remove a plug engaged with the outlets of the module 200'. The lever 232 can be constructed and arranged as shown in U.S. Patent Application Publication No. 2021 / 0288434. The latch lever 232 can be pivotally coupled to the housing 230 adjacent to each of the outlets 20a-20e. Each latch lever 232 is movable (e.g., pivotable) between a latched position in which a mating plug can be inserted and held therein and an unlatched position in which the mating plug can be removed from the module 200'.

[0045] Preferably, a differential detector embodied as a microcontroller (not shown) can be assembled on the PCB 240 of each preferred outlet module 200'. An exemplary microcontroller for use in the PDU 10 is a 32-bit ARM Cortex M4 (with an embedded DSP core) manufactured by STMicroelectronics and identified by the part number STM / STM32F446ZC. The microcontroller 110 can determine the current and power related parameters of the outlet module 200 and other components of the PDU 10. More preferably, the microcontroller 110 is configured to monitor, detect, and report power related parameters for each outlet, as shown and described in any one of U.S. Patent No. 8,321,163, U.S. Patent No. 8,305,737, U.S. Patent No. 8,694,272, and U.S. Patent No. 9,952,261, each of which is incorporated by reference. Thus, referring to FIG. 2, each of the preferred modules 200a, 200b, 200c... 200n of the PDU 10 preferably includes a relay device 140 and a relay driver circuit 150, each of which is electrically connected to the microcontroller 110, in addition to the preferred residual current monitoring circuit 100 and voltage sensing circuit 120. Thus, each module 200a, 200b, 200c... 200n is preferably configured as an intelligent outlet module of the PDU 10. Further, the PDU 10 can include a residual current monitor in the input cord. As shown in FIG. 2, the PDU 10 can include an internal input cord residual current monitor 160 having one or more current sensors where a single-phase or polyphase input cord is associated with a current transformer (CT) to detect current leakage. In addition, the PDU can include an input power meter 161 having an upstream RCM or a downstream RCM (not shown), as exemplarily shown. The current sensors of the input cord residual current monitor 160 are preferably of type B that measure AC current (up to 2000 Hz) as well as pulsating and smoothed DC current in accordance with IEC-60755.A preferred embodiment of the PDU preferably realizes residual current monitoring in the outlet for an AC current in the range of 42 to 2000 Hz.

[0046] As described herein, by providing residual current monitoring in a preferred embodiment of the PDU 10, additional fault isolation information is provided to maintenance personnel, enabling the maintenance personnel to correct the fault condition and recover the affected IT equipment while minimizing the impact on the system uptime. Similar to the PDU of U.S. Patent No. 9,952,261, a preferred embodiment of the PDU 10 can be configured using "Power Sensing per Outlet" (i.e., "POPS"), which refers to the concept of detecting the load coupled to each outlet and monitoring the power consumption at each outlet. Thus, the preferred microcontroller 110 of the outlet module receives the current information of each outlet 20 of the module 200 along with the voltage information, so that load detection can be calculated for each outlet along with various power-related metrics, and this information can be reported via the network 4 to the network power manager 6 or other network-connected computers or devices. The microcontroller 110 can be interconnected via a communication bus (such as an RS485 bus, I2C bus, or SMBus). A preferred embodiment of the PDU 10 can include a microcontroller 110 for reporting, for each outlet, (a) residual current (RC), (b) voltage RMS (Vrms), (c) current RMS (Irms), (d) apparent power (VA), (e) active power (W), (f) power factor (pF), and (g) crest factor via the network 4. This data can be received by an external system that collects the outlet information for which the data is provided and used to determine the metrics as described above or to provide information. By using an Internet interface to monitor the power consumption at each outlet, detailed power information is provided, enabling grouping of outlets and determining the kilowatt consumption per device, per group of devices, per PDU, or per cabinet. The power consumption can also be determined, as described above, for each rack, row of racks, or entire data center, etc., by clustering the outlet information across multiple IP addresses and PDUs.This enables viewing integrated PDU information, power, and environmental status within a data center or across multiple locations, a centralized location for capacity planning, reports, and trends, multiple views, automatic discovery of all PDU devices, alarm details, the ability to manage PDUs, global or individual outlet control, and logging.

[0047]

[0047] Those skilled in the art will appreciate that the various exemplary logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, firmware, or any combination thereof. For the sake of clarity in explaining this interchangeability, the various exemplary components, blocks, modules, circuits, and steps have been generally described above in terms of their functionality. Whether such functionality is implemented as hardware, software, and / or firmware depends upon the particular application and design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in various ways for each particular application, but such implementation decisions should not be construed as causing a departure from the scope of the present invention.

[0048]

[0048] In the case of a hardware implementation, the processing unit may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, or any combination thereof. In the case of a firmware and / or software implementation, the methodology may be implemented with modules (e.g., procedures, functions, etc.) that perform the functions described herein.

[0049] The foregoing description of the disclosed embodiments has been provided to enable a person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present invention. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A power distribution unit, comprising a power distribution unit housing, a power source disposed within the housing, the power source including a plurality of input conductors, a plurality of electrical outlets disposed within the housing, and having, each electrical outlet among the plurality of electrical outlets including, a plurality of connectors including a first connector electrically connected to one input conductor and at least a second connector electrically connected to a different input conductor, an associated residual current monitoring circuit, and having, the associated residual current monitoring circuit including, at least one current sensor associated with the first connector and the at least second connector, the power distribution unit including, a differential detector electrically connected to the at least one current sensor for determining a residual current, A power distribution unit.

2. The at least one current sensor includes, a first current sensor associated with the first connector for defining a first current sense output, a second current sensor associated with the at least second connector for defining a second current sense output, and having, The differential detector determines a current difference between the first current sense output and the second current sense output. The power distribution unit according to claim 1.

3. The plurality of input conductors includes a first phase conductor and at least another phase conductor, at least one electrical outlet among the plurality of electrical outlets including, the first connector electrically connected to the first phase conductor, ​​​​​​​​​​​​The second connector of the at least one socket electrically connected to the other conductor The power distribution unit according to claim 2, having . **Claim 4** The plurality of input conductors include a second conductor and a third conductor The power distribution unit according to claim 3, wherein the second connector of the at least one socket is electrically connected to one of the second conductor or the third conductor. **Claim 5** The power distribution unit further comprises another socket among the plurality of sockets The another socket has A first phase connector electrically connected to the second conductor The second conductor electrically connected to the third conductor The power distribution unit according to claim 4, having . **Claim 6** The power distribution unit according to claim 5, wherein the power source defines a delta configuration. **Claim 7** At least the second conductor includes a neutral conductor The power distribution unit according to claim 6, wherein the power source defines any one of a single-phase power source or a polyphase power source having either a delta configuration or a Y-shaped configuration. **Claim 8** The plurality of input conductors include a first conductor, a second conductor, a third conductor, and a neutral conductor At least one of the plurality of sockets has A first connector electrically connected to one of the first conductor, the second conductor, or the third conductor The second connector of the at least one socket electrically connected to the neutral conductor The power distribution unit according to claim 1, having . **Claim 9** The power distribution unit according to claim 7, wherein the input power defines either a Y-shaped configuration or a delta configuration.

10. The differential detector includes a microcontroller, The power distribution unit according to claim 1, wherein each of the first current sensor and the second current sensor is a toroidal current transformer.

11. Each socket has a core body having a surface defining a plurality of apertures, A first power terminal is disposed within a first aperture of the plurality of apertures to define the first connector, The power distribution unit according to claim 1, wherein a second power terminal is disposed within a second aperture of the plurality of apertures to define at least the second connector.

12. The plurality of input conductors includes a ground conductor, The power distribution unit according to claim 11, wherein each socket includes a ground terminal disposed within a third aperture of the plurality of apertures to define a third connector of the plurality of connectors electrically connected to the ground conductor.

13. The core of each socket is oriented such that each surface is disposed within a common first plane, and each of the first current sensor and the second current sensor is assembled on at least one circuit board oriented within at least a second plane parallel to the first plane. The power distribution unit according to claim 12.

14. The at least one circuit board includes two circuit boards, The power distribution unit according to claim 13, wherein the first current sensor and the second current sensor are assembled on different circuit boards.

15. The cores of the respective power outlets are oriented such that each surface is disposed within a common first plane, and each of the first current sensor and the second current sensor is assembled on at least one circuit board oriented within at least a second plane perpendicular to the first plane. The power distribution unit according to claim 12.

16. The at least one circuit board includes two circuit boards, and the first current sensor and the second current sensor are assembled on different circuit boards. The power distribution unit according to claim 15.

17. A plurality of power outlets define a module, and each power outlet of the module is connected to each other. The power distribution unit according to claim 1.

18. Each power outlet of the module includes a terminal, The terminal has an aperture formed therein, The module includes a circuit conductor that extends through the aperture of each terminal to connect the plurality of power outlets to each other. The power distribution unit according to claim 17.

19. The power distribution unit according to claim 1, further comprising at least one voltage sensing network.

20. The residual current monitoring circuit monitors an AC current in the range of 42 to 2000 Hz. The power distribution unit according to claim 1.

21. The power distribution unit according to claim 1, further comprising an input power cord and an input residual current monitor associated with the input power cord.

22. The at least one current sensor is A first current sensor associated with the first connector to define a first current sense output, A second current sensor associated with each of the first connector and the at least second connector, The power distribution unit according to claim 1, comprising

23. The power distribution unit according to claim 1, wherein the at least one current sensor comprises current sensors associated with each of the first connector and the at least second connector.

24. A socket module, comprising At least one circuit board; A first pair of current sensors assembled on the at least one circuit board; At least a second pair of current sensors assembled on the at least one circuit board; At least one differential detector assembled on the at least one circuit board for determining a difference between current sense outputs of each pair of current sensors; A first power socket associated with the first pair of current sensors; At least a second power socket associated with the at least second pair of current sensors; The socket module comprising the above.

25. The differential detector includes a microcontroller, The socket module according to claim 24, wherein each of the first pair of current sensors and the at least second pair of current sensors includes a toroidal current sense transformer.

26. Each of the first power socket and the at least second power socket includes a core having a surface defining a plurality of apertures, At least a first power terminal is disposed within a first aperture of the plurality of apertures and is associated with one of the current sensors of the associated pair of current sensors, A second power terminal is disposed within a second aperture of the plurality of apertures associated with the other current sensor of the associated pair of current sensors. The socket module according to claim 25.

27. The cores of the respective plugs are oriented such that the surfaces of the respective cores are disposed in a common first plane, and the at least one circuit board is oriented in at least a second plane parallel to the first plane. The plug module according to claim 26.

28. The at least one circuit board includes two circuit boards, and the associated pair of current sensors are assembled on different circuit boards. The plug module according to claim 27.

29. The cores of the respective plugs are oriented such that the surfaces of the respective cores are disposed in a common first plane, and the at least one circuit board is oriented in at least a second plane perpendicular to the first plane. The plug module according to claim 26.

30. The at least one circuit board includes two circuit boards, and the associated pair of current sensors are assembled on different circuit boards. The plug module according to claim 29.

31. A method for residual current detection in a power distribution unit, the method comprising: providing a residual current monitor for a plurality of power plugs; detecting a current leakage of at least one plug by the residual current monitor as a difference between a supply current and a return current of each plug; and a method.

32. The step of monitoring in a plug among a plurality of plugs includes: associating a first connector of the plug with a first current sensor and generating a first current sense output of the first current sensor; associating a second connector of the plug with a second current sensor and generating a second current sense output of the second current sensor; A step of determining a difference between the first current sense output and the second current sense output; The method according to claim 31, comprising:

33. The step of associating the first connector of the outlet with the first current sensor includes associating a first power terminal of the outlet with a toroidal current transformer, The method according to claim 32, wherein the step of associating the second connector of the outlet with the second current sensor includes associating a second power terminal of the outlet with a toroidal current transformer.

34. Detecting a load coupled to a first outlet among the plurality of outlets and detecting a load coupled to at least a second outlet among the plurality of outlets; Detecting current leakage in the plurality of outlets; Identifying which of the outlets between the first outlet and the at least second outlet has current leakage; The method according to claim 32, further comprising:

35. An outlet module for use in a PDU, the outlet module comprising: A core having a surface defining a plurality of apertures; A first power terminal disposed within a first aperture of the plurality of apertures; A second power terminal disposed within a second aperture of the plurality of apertures; A first current sensor associated with the first power terminal; A second current sensor associated with the second power terminal; An outlet module comprising:

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