Circuit Breaker Forensics for Power Distribution Units

Abstract

A power distribution system and method are disclosed in which a power distribution unit (PDU) includes an overcurrent protection device and per-outlet current sensing at each of a plurality of electrical outlets of the PDU. The described embodiments enable identification of an electronic device connected to a particular outlet or an electronic device that may have tripped the overcurrent protection device. A method for outlet identification in a PDU with multiple electrical outlets includes detecting whether either the peak current or half-cycle root mean square (RMS) current at each outlet exceeds a selected threshold prior to the occurrence of a trip event associated with the overcurrent protection device.

Description

[Technical Field]

[0001] The present disclosure relates to power distribution units, and more particularly to power distribution units that provide methods and systems for detecting electrical outlets that have caused an overcurrent protection device (OCPD) trip event. [Background technology]

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

[0003]

[0003] A further understanding of the nature and advantages of the present technology may be realized by reference to the following drawings, in which like components or features may have the same reference label. [Brief explanation of the drawings]

[0004] [Figure 1] FIG. 1 is a diagram of an exemplary power distribution unit (PDU).

[0005] [Figure 2A] FIG. 2A is an exemplary single-line diagram of a base rack PDU.

[0006] [Figure 2B] FIG. 2B is an exemplary wiring diagram of the PDU of FIG. 1 connected to a power input and a network.

[0007] [Figure 2C]FIG. 2C is another exemplary wiring diagram of the PDU of FIG.

[0008] [Figure 3] FIG. 3 is a block diagram of an exemplary embodiment of an outlet module for use in the PDU of FIG.

[0009] [Figure 4] FIG. 4 is a block diagram of another exemplary embodiment of a multiple outlet module for use in the PDU of FIG.

[0010] [Figure 5] FIG. 5 is a block diagram of yet another exemplary embodiment of a multiple outlet module for use in the PDU of FIG.

[0011] [Figure 6] FIG. 6 is a flow chart of an exemplary method for trip detection forensics.

[0012] [Figure 7] FIG. 7 is a flowchart of another exemplary method for trip detection forensics.

[0013] [Figure 8] FIG. 8 is an exploded perspective view of one exemplary embodiment of an outlet module for use in the PDU of FIG. [Figure 9] FIG. 9 is another exploded perspective view of an exemplary embodiment of an outlet module for use in the PDU of FIG.

[0014] [Figure 10] FIG. 10 is a flowchart of an exemplary method for monitoring multiple electrical outlets of an electrical distribution device and identifying whether an outlet has caused a trip event associated with an overcurrent protection device of the electrical distribution device.

[0015] [Figure 11] FIG. 11 is an example of the output of a current sensor and the corresponding calculated half-period RMS output. DETAILED DESCRIPTION OF THE INVENTION

[0016] 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 those skilled in the art with an enabling description for practicing embodiments of the present invention. Various changes may be made to the function and arrangement of elements. Accordingly, various embodiments may omit, substitute, and / or add various procedures or components as appropriate. For example, aspects and elements described with respect to particular embodiments may be combined in various other embodiments. It should also be understood that the following systems, devices, and components, individually or collectively, may be components of larger systems, and that other procedures may take precedence over or otherwise modify their application.

[0017] When using a power distribution unit (PDU), the overcurrent protection device (OCPD) may trip, and customers are interested in knowing why the trip occurred, i.e., which electronic device attached to a particular PDU outlet caused the OCPD to trip. The goal is to quickly replace the electronic device to minimize downtime and also to avoid having to perform tests on each of the electrical outlets in the power distribution unit.

[0018]

[0018] Embodiments of the disclosed technology relate to a PDU capable of determining which of multiple electronic devices connected to the PDU may have been the cause of a trip event associated with the PDU's OCPD. The described embodiments achieve this by using current sensors per outlet to enable detection of the specific electronic device that caused the trip event, thereby minimizing data center downtime and / or mitigating or eliminating electrical hazards. In one example, this is achieved by identifying a condition, e.g., an electrical outlet whose corresponding current sensor measures a current that is subsequently used to calculate (e.g., by a microcontroller) a current characteristic that exceeds a specified threshold. In another example, if the outlet does not meet the condition, no trip cause is reported. This can occur when the combined current of electronic devices on a single electrical branch exceeds the OCPD trip current, but a single electronic device current does not exceed the OCPD trip current. In yet another example, if multiple electrical outlets meet this condition, the one with the highest identified current characteristic is reported as having caused the OCPD trip event.

[0019] FIG. 1 illustrates an exemplary embodiment of a PDU 10 including a housing 12 having a plurality of outlets 20 (also referred to as "receptacles," "outputs," "electrical outlets," or "power outlets") assembled therein for supplying power to individual assets or devices, such as assets used in data center operations. Assets may be assembled within an equipment rack and appropriately plugged into one of the PDU's outlets 20. Accordingly, the PDU 10 may be configured to be mounted vertically or horizontally. The PDU 10 is configured to internally receive power input for supply and distribution to connected assets via the outlets 20. As shown, the PDU may include an internally wired input power cord 30 that extends externally and terminates in an associated plug 32 for connection to a power source in a conventional plug-and-receptacle connection. Alternatively, the PDU 10 may 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 outlet of the PDU has detected an overcurrent. The visual display may display other information, such as, for example, power consumption, voltage, and / or current per outlet. Alternatively or additionally, the PDU 10 may be coupled to an external display to communicate such information. The outlets 20 may be grouped and configured to define one or more outlet modules 200, as described herein. For example, each outlet module 200 (also referred to as a "meter board") of the illustrated PDU 10 includes six outlets 20a-20f. However, it should be understood that other embodiments of the outlet module 200 may include fewer or more outlets 20, provided that at least one outlet is configured with a current monitoring circuit and an overcurrent protection device in the manner described herein.

[0020] In existing implementations (e.g., as shown in FIG. 2A, which shows a simplified two-branch single-line diagram), without the circuit breaker forensics described herein, determining which electronic device connected to one of the outlets was responsible for the trip event is a manual, time-consuming procedure. For example, this manual determination typically involves:

[0021] (1) turning off or disconnecting each of the electronic devices connected to the outlet;

[0022] (2) switching on a circuit breaker; and

[0023] (3) Turn on each of the electronic devices (or connect each of the electronic devices to a PDU) in turn until the failed device is located.

[0024] Furthermore, if the electronic device failure is a transient event, this manual procedure may not be able to reliably determine the failed electronic device.

[0025]

[0025] For example, the disclosed embodiments described in the context of Figures 2B and 2C overcome the drawbacks associated with the manual determinations discussed above by implementing circuit breaker forensics using current sensors in each electrical outlet to measure the current passing therethrough and automatically determine whether certain current characteristics exceed predetermined thresholds.

[0026] The block diagram of FIG. 2B illustrates an exemplary system 2 including a PDU 10 for supplying power to one or more associated computing assets, such as devices on a computer network 4, which may include computing and processing assets in an enterprise data center. The PDU 10 can communicate with a data center operator using a workstation or other device used to manage the data center or other enterprise, or with a network application, such as a power manager application 6, via the computer network 4. As shown schematically, an outlet module 200a of the PDU 10 is wired and configured with an overcurrent protection device 100a, which functions as a fuse (or common circuit breaker) and fails or creates an open circuit when a current measured by one or more of the electronic devices connected to the outlets 20a-20n of the module 200a exceeds a threshold. This trip event removes power from all electronic devices connected to the outlets 20a-20n. 2B, the thick lines (e.g., from input power meter 161 to each of the OCPDs and intelligent power modules) represent high voltage, and the thin lines (e.g., between network card 60) are low voltage connectors. In some embodiments, each of modules 200a, 200b, 200c is wired and configured with its own overcurrent protection device 100a, 100b, 100c, respectively. In other embodiments, two or more modules are connected to a single OCPD.

[0027] 2C illustrates an exemplary single-line diagram of a switched rack PDU implemented in accordance with the disclosed technology. As shown therein, each set of receptacles (20a, ..., 20n, corresponding to devices plugged into the switched rack PDU) is connected to a corresponding voltage sensor 120 ("VS") and circuit breaker 100a ("OCPD"). Each receptacle (e.g., 20a) is configured with its own relay (e.g., 140a) ("RLY") and current sensor (e.g., 110a) ("CS"), which enables per-outlet current monitoring and switching. The PDU further includes a microcontroller ("μP"), a display ("LCD"), and a network communication function 60 ("COM").

[0028]

[0028] Embodiments of the disclosed technology enable efficient identification of electronic devices that may have caused a trip event. To determine which of the electronic devices connected to electrical outlets 20a-20n may have caused the trip event, the described embodiment of PDU 10 is configured to provide "per-outlet" current sensing, e.g., each outlet has an associated current sensor 110. In one example, current sensor 110 is configured to measure a signal representative of the current, which is then processed by a microcontroller (not shown in FIG. 2B and labeled "μP" in FIG. 2C) associated with current sensor 110. In another example, the current signal from current sensor 110 is sampled by the μP, e.g., 64 times per AC cycle, and measurements from the past few seconds are stored for analysis by forensic algorithms that may be implemented in the microcontroller.

[0029] In some embodiments, when the PDU detects a circuit breaker trip (e.g., the OCPD 100a indicates a trip event), a forensic algorithm is configured to determine the electronic device causing the trip event by examining a memory buffer of instantaneous current measurements. In one example, the current measurements are generated by sampling a signal (representing current) from a current sensor. In some scenarios, the forensic algorithm calculates a ½ AC cycle RMS current value from a memory buffer associated with each electronic device connected to each of the outlets 20a-20n. In other scenarios, the forensic algorithm identifies a peak instantaneous current measurement from a memory buffer associated with each electronic device connected to each of the outlets 20a-20n. In one example, the ½ AC cycle RMS current value from the memory buffer may be used when the circuit breaker trips in only ½ of the AC power cycle.

[0030] In the embodiment described herein, the microcontroller is configured to communicate the detection of a current characteristic (e.g., ½ AC periodic RMS current or peak current) exceeding a threshold to a display 40 or otherwise communicate the detection of the current characteristic via network 4 to a network device or operator so that appropriate personnel can address the issue. Accordingly, PDU 10 includes an LCD display, one or more LED indicators, and / or a network interface card 60 for communicating with devices on network 4. Each outlet 20 a-20 n is further associated with a voltage sensor 120, as well as a relay 140 and a relay driver 150; it should be noted that the relay 140 and relay driver 150 are optional.

[0031] In some embodiments, LED indicators located next to one or more electronic devices connected to outlets 20a-20n flash and / or change color to indicate that those devices have lost power due to a circuit breaker trip. Contrasting colors and / or flash rates / patterns are used to indicate the specific electronic device that caused the circuit breaker trip. Additionally or alternatively, a textual indication of the circuit breaker trip and electronic device failure is displayed on the PDU's LCD display. In some implementations, the LEDs are controlled by a first microcontroller that is different from the second microcontroller that controls the LCD display.

[0032] In some embodiments, event notifications of circuit breaker trip events and / or the outlets that caused the trip events are sent by the PDU via Simple Network Management Protocol (SNMP) traps. In other embodiments, current measurements and / or circuit breaker trip status associated with each outlet may be remotely polled using SNMP or JavaScript Object Notation (JSON) formatted messages. In yet other embodiments, the PDU may be configured to support a web browser that can be used to determine circuit breaker status and current measurements.

[0033] In some embodiments, the PDU is configured to communicate the following information:

[0034] - an indication that the OCPD has tripped and / or corresponding details;

[0035] - an indication of a suspect outlet and / or current characteristics exceeding a threshold; and

[0036] - The captured waveform of the trip event.

[0037]

[0037] The information listed above may be communicated, for example, via:

[0038]

[0038] - a display 40,

[0039]

[0039] - a network card 60 to a network device and / or operator in the network 4,

[0040] - a web server,

[0041] -SNMP queries and / or traps,

[0042] - Command Line Interface (CLI), e.g., telnet or ssh,

[0043] USB serial access and CLI to local operator, and / or

[0044]

[0044] - LED blinking pattern next to the outlet.

[0045] FIG. 3 shows a block diagram of an exemplary outlet module 200 having an overcurrent protection device (OCPD) 100 and a current sensor 110 per outlet electrically connected to a power supply or power source 112 via a respective conductor of a plurality of conductors. The power source 112, which may be external to the PDU 10, connects to the PDU 10 via the power cord of the power source 112 and carries one or more phases of electrical power input to the PDU 10. As shown, each outlet 20a-20h of the module 200 has two or more connectors 22 for electrically connecting to two conductors of the power source 112. Each outlet 20a-20h also includes an associated current sensor 110 capable of measuring the electrical current at that electrical outlet. In some embodiments, the outlet modules described herein can include a voltage sensing network 120 for determining the voltage at each outlet 20a-20h along with other power-related parameters described herein. Each outlet 20a-20h is also connected to ground GND within power supply 112, although these connections from outlets 20a-20h are not shown in Figure 3. Additionally, unlike Figure 2B, the embodiment shown in Figure 3 does not include a relay or relay driver associated with each electrical outlet 20a-20h.

[0046] FIG. 3 specifically illustrates an exemplary embodiment of a module (or meter board) 200 electrically connected to two conductors L1, L2 of a power source 112. In the line-to-line distribution configuration of the PDU shown in FIG. 3, a first conductor L1 may be connected to one phase of AC power in the power source 112, and a conductor L2 may be connected to a second phase of AC power in the power source 112. Thus, the outlet module 200 may be configured with each outlet 20 having one connector 22a electrically connected to the first conductor L1, which carries the line power of the first phase, and another connector 22b electrically connected to the second conductor L2, which carries the line power of the second phase. Also shown in FIG. 3, an overcurrent protection device (OCPD) 100 is wired between the power source 112 and the module 200, spanning both L1 and L2. In this example of a single-phase power source, the OCPD includes a single double-pole interlocked circuit breaker with connections to both L1 and L2. Here, L1 or L2 may trip (or interrupt) individually, but the OCPD 100 disconnects (or interrupts) both conductors L1 and L2.

[0047] Alternatively, in a line-neutral distribution configuration of the PDU (not shown in FIG. 3), the conductors may be connected to different phases of the power source 112. Thus, for example, each outlet 20 of the module 200 may have one connector 22a electrically connected to a first conductor L1 carrying the line power of the first phase, and another connector 22b electrically connected to a second conductor L2 connected to the neutral. In this example, a single-pole OCPD is used for each phase of the polyphase configuration of the power source 112.

[0048] In some embodiments, the current signal is continuously measured by a current sensor and sampled by a processor on the network card, i.e., a network processor, to determine current characteristics. As described herein, the network processor continuously performs either a half-period RMS current calculation operation or a peak value determination operation based on the samples in the buffer. The most recent sample in the buffer prior to a trip event is examined after a trip event associated with the corresponding OCPD is detected. In one example, a trip event is detected when the voltage associated with each of the electrical outlets connected to the OCPD falls below a threshold value, e.g., 75% of the nominal voltage value or is within a range of 65% to 85% of the nominal voltage value. In one example, the specified threshold for current sensor detection may be set to 125% of the OCPD rating.

[0049] In some embodiments, a half-period root mean square (RMS) function may be used in the current calculations performed by the microcontroller. In other embodiments, the peak amplitude may be used.

[0050]

[0050] With a multi-phase power source 112, the PDU 10 can have either a delta power output wiring configuration or a wye power output wiring configuration, as shown in Figures 4 and 5, respectively. As shown in Figure 4, a multi-phase power source 112 is connected to a three-phase delta-configured PDU. The PDU 10 in Figure 4 shows three outlet modules 200a, 200b, and 200c with outlets 20 electrically connected to conductors L1, L2, and L3 in various combinations, and individual OCPDs 100a, 100b, and 100c spanning both conductors entering the modules.

[0051] In some embodiments, each module 200a, 200b, 200c includes a microcontroller 115a, 115b, 115c for receiving current signals from a respective associated current sensor 110a of each outlet 20. Time series current measurements are generated by sampling the signal from the current sensor 110a, which allows the microcontroller 115a, 115b, 115c to first determine the current characteristics (either by calculating half-cycle RMS current or by identifying peak currents) and then detect whether the current characteristics exceed a threshold for each outlet 20 of the respective associated module 200a, 200b, 200c.

[0052] FIG. 5 illustrates a polyphase power source 112 connected to a three-phase wye-configured PDU. The partial PDU illustrated in FIG. 5 shows the first connectors 22a of the outlets of three outlet modules 200a, 200b, and 200c electrically connected to conductors L1, L2, and L3, respectively, between which are located respective overcurrent protection devices (OCPDs) 100a, 100b, and 100c. A current sensor 110a associated with the first connector 22a in each outlet 20 detects current flowing through the outlet. Again, each outlet module 200a, 200b, and 200c includes a microcontroller 115a, 115b, and 115c for receiving a current sense output from the associated current sensor 110a of each outlet 20a-20h. Each current sensor 110a continuously measures a current signal that can be used to determine whether the associated outlet is responsible for a trip event of the corresponding OCPD.

[0053]

[0053] In some embodiments, the two-pole "ganged" OCPD (or circuit breaker) of Figures 3 and 4 may be implemented using part number J61-X0-26-127-K3D-D3 manufactured by Carling Technologies, and the single-pole circuit breaker (e.g., shown in Figure 5) may be implemented using part number J62-X0-26-128-K3D-D3 manufactured by Carling Technologies.

[0054] In the above-described embodiment, each of the microcontrollers on each outlet module (or meter board) is configured to sample the current signal, use the samples to determine a current characteristic, compare the current characteristic to a threshold, and report the results to a main controller (e.g., network card 60 of FIG. 2B). Alternatively, each meter board may transmit the current characteristic to the main controller. In other embodiments, the main controller is configured to receive the current signal and perform the sampling, determining, and comparing operations.

[0055] FIG. 6 shows a flowchart of an exemplary method for trip detection forensics that may be implemented by a meter board, e.g., the output module 200a of FIG. 2B. As shown therein, the outlet (meter board) measures voltage and current, continuously updates the voltage and current waveforms, and always stores the most recent 128 samples (corresponding to two AC cycles). Here, the measurements include 64 samples per AC cycle generated using an analog-to-digital converter (ADC). In one example, the microcontroller for the meter board is configured to calculate average voltage and current RMS values ​​over one second. The meter board continuously scans for faults in the AC supply voltage by (a) determining a "fault voltage threshold," calculated as the greater of 20 V or 25% of the last measured one-second RMS value, and (b) indicating a voltage fault if any one of the following three conditions is met:

[0056] (i) checking a single voltage sample to determine if 16 consecutive samples are below the failure voltage threshold, or if the difference between two subsequent samples is below the threshold for 16 consecutive samples, the threshold being calculated as the greater of 2V or 5% of the last measured 1-second RMS value. For example, if the most recent 1-second RMS value is 25V, then 5% x 25V = 1.25V, and the threshold is calculated as max(2V, 1.25V) = 2V; or

[0057] (ii) checking for the presence of zero crossings (e.g., using a voltage phase-locked loop (PLL)) to determine whether there are two zero crossings at the expected time; or

[0058] (iii) Checking the half cycle RMS voltage value to determine if the half cycle RMS is below the fault voltage threshold.

[0059]

[0059] Once a voltage supply failure is determined (i.e., one or more of the above three conditions are met), indicating an OCPD trip event, the meter board microcontroller determines the likely trip cause by:

[0060] (i) Wait another 16 samples (1 / 4 AC period),

[0061] (ii) for each outlet, determining the highest half-cycle RMS current value, for example by scanning the signal from a current sensor;

[0062] (iii) Designating an outlet as a potential trip source if either:

[0063] (a) The highest determined half-cycle RMS current value exceeds 125% of the OCPD rating (i.e., an overload condition); or

[0064] (b) At least two of the current samples fully saturate the ADC (i.e., a short circuit condition). In one example, fully saturating the ADC corresponds to a sample taking the maximum value within the data range for that sample.

[0065] (iv) if there is more than one outlet that could be considered a potential trip source, select the outlet with the highest ½ cycle RMS; and

[0066] (v) After a suspect outlet has been identified, taking a snapshot of the current and / or voltage waveforms of that outlet.

[0067] In this embodiment, the microcontroller on the meter board reports the outlet ID of the suspect outlet, the determined 1 / 2 cycle RMS current value, and the waveform to the main controller.

[0068] In some embodiments, the meter board may implement the above algorithm using peak current values ​​(instead of half cycle RMS current values) as the current characteristic.

[0069] FIG. 7 shows a flowchart of an exemplary method for trip detection forensics that may be implemented by a main controller, such as the network card 60 of FIG. 2B. As shown therein, the main controller retrieves the voltage RMS value of each outlet every second. If the voltage of all outlets connected to the circuit breaker is less than 75% of the inlet phase voltage feeding the circuit breaker, the main controller considers the OCPD to be tripped or open. If this condition is not met, the OCPD is considered closed, and connected outlets that were turned off due to a previous open OCPD condition are turned on. In some embodiments, connected outlets are turned on only after an explicit reset command is received or one or more administrator intervention actions occur.

[0070] At this time, the main controller searches the outlet boards (or meter boards) connected to a given circuit breaker for the reported trip cause. The outlet with the highest reported current characteristic is reported to the user as the most likely trip cause. In one example, reporting may be performed via a web-based graphical user interface (GUI) or command line interface (CLI). In another example, JSON-RPC is used. Finally, the waveforms associated with the outlet that was the potential trip cause are retrieved.

[0071] 8 and 9 show two exploded views of an exemplary module 200′ assembled with six receptacles 20′a-20f disposed within a module tray or housing 230 and mating with toroidal current sensors 110a. The current sensors 110a are assembled with their respective output leads 102a assembled to a printed circuit board PCB 240. Thus, the sensors 110a are disposed between the receptacle core 220 and the PCB 240, and more specifically, between the module housing 230 and the PCB 240.

[0072] By providing current monitoring and overcurrent protection to embodiments of PDU 10 as described herein, additional fault isolation information may be provided to maintenance personnel, enabling them to correct the fault condition and restore affected IT equipment with minimal impact to system uptime. In one example, the following isolation procedure may be implemented to restore power to all but the failed electronic device:

[0073] (1) When a trip event occurs and a faulty electronic device is identified, a relay that controls power to the faulty device is opened;

[0074] (2) resetting the circuit breaker to restore power to all electronic devices except the failed device;

[0075] (3) The failed device is disconnected and replaced / repaired; and

[0076] (4) Power is restored to the replaced / repaired device by closing the relay of the replaced / repaired device using the PDU's local keypad / LCD or remotely via the PDU's web browser interface.

[0077] In some embodiments, similar to the PDU of U.S. Patent No. 9,952,261, embodiments of the PDU 10 may be configured with "Per Outlet Power Sensing" or "POPS," which refers to the concept of detecting the load coupled to each outlet and monitoring the power draw at each outlet. Thus, the microcontroller 115 of the outlet module (e.g., shown in FIGS. 3, 4, and 5) receives current information for each outlet 20 of the module 200, along with voltage information, so that the load current, along with various power-related metrics, can be calculated for each outlet, and this information can be reported over the network 4 to the network power manager 6 or other networked computer or device.

[0078] In some embodiments, the PDU may be configured with a latching relay.

[0079]

[0079] In some embodiments, each electrical outlet 20 may be a metered outlet (having one or more sensors per outlet, each associated with a display configured to display both a status and a reading corresponding to the measured value) or a switched outlet (which may be switched on or off to selectively control the flow of current therethrough, in one example, by software).

[0080] In some embodiments, the microcontroller 115 may be connected to a communications bus (such as an RS485 bus, an I2C bus, or an SMBus). Embodiments of the PDU 10 may include a network interface card (e.g., network card 60) for reporting over the network 4. These measurements may be made by sensors on both metered and switched outlets. These measurements may be received by an external system that collects outlet information and used to determine metrics or provide information such as those described above.

[0081] In some embodiments, each of the switched electrical outlets in a PDU can be collectively configured to be either latching or non-latching, and the PDU is configured with an inrush (or in-rush) guard, which is a configurable minimum (delay) interval between two electrical outlets of the PDU being switched on. The purpose of the inrush guard is to avoid overloading an inlet or OCPD due to the combined inrush current from many loads being switched on simultaneously. For latching relays, where the relay is configured to remain in its previous state upon power loss, the inrush guard is not effective when unit power is restored. For PDUs with multiple inlets, the inrush guard can switch on an outlet from each inlet at a time. For inlets with two or three phases, the inrush guard can switch on multiple outlets at once, in various combinations.

[0082]

[0082] An embodiment of the disclosed technology provides an electrical distribution apparatus comprising: a housing; a power inlet; a plurality of electrical outlets, each of the plurality of electrical outlets (a) adapted to supply power to an associated electronic device and (b) having an associated current sensor; at least one overcurrent protection device; and at least one processor coupled to the at least one overcurrent protection device and each associated current sensor, wherein the at least one processor is configured to receive signals representing current from each associated current sensor; calculate a current characteristic for each associated current sensor based on the signals; detect a trip event associated with the at least one overcurrent protection device; and determine whether the at least one calculated current characteristic exceeds a selected threshold prior to detection of a trip event.

[0083] In some embodiments, the processor is a microcontroller (e.g., μP in FIG. 2C) on an instrumentation board that is different from the network interface card (e.g., network card 60 in FIG. 2B). In other embodiments, the processor is a network processor on a network interface card (NIC). In yet other embodiments, the processor is a microcontroller on a NIC that also includes a network processor.

[0084]

[0084] In some embodiments, upon determining that the at least one calculated current characteristic exceeds a selected threshold, the at least one processor is further configured to correlate the at least one calculated current characteristic to at least one of a respective associated current sensor or an associated electronic device of each associated current sensor.

[0085]

[0085] In some embodiments, when the at least one processor determines that the respective current characteristic exceeds a selected threshold prior to detection of a trip event, the at least one processor is further configured to identify a suspect electrical outlet or a suspect electronic device in the suspect electrical outlet corresponding to the respective current characteristic, and transmit an identifier associated with the suspect electrical outlet to a location remote from the power distribution device.

[0086]

[0086] In some embodiments, when the at least one processor determines that two or more respective current characteristics exceed a selected threshold value prior to detection of a trip event, the at least one processor is further configured to: identify two or more suspect electrical outlets or suspect electronic devices in two or more suspect electrical outlets corresponding to the two or more respective current characteristics; and transmit, to a location remote from the power distribution device, an identifier associated with an associated electrical outlet of the two or more suspect electrical outlets that measured the highest value of the respective current characteristic.

[0087]

[0087] In some embodiments, the at least one processor is further configured to transmit a waveform capture corresponding to a signal from at least one of the associated current sensors to a location remote from the power distribution device.

[0088]

[0088] In some embodiments, when the at least one processor determines that each of the respective current characteristics does not exceed a selected threshold, the at least one processor is further configured to transmit a message to a location remote from the power distribution device indicating that none of the plurality of electrical outlets is an individual cause of the trip event.

[0089] In some embodiments, the power distribution equipment includes a voltage sensor, and detecting a trip event associated with the at least one overcurrent protection device is based on a signal representative of a voltage from the voltage sensor.

[0090]

[0090] In some embodiments, calculating the current characteristics is based on sampling the signal from each associated current sensor.

[0091] In some embodiments, a trip event associated with the at least one overcurrent protection device corresponds to the voltage of at least one of the plurality of electrical outlets being less than a selected percentage or percentage range of the voltage of the power inlet. In one example, the selected percentage is 75%. In another example, the selected percentage range is 65% to 85%.

[0092]

[0092] In some embodiments, at least one electrical outlet of the plurality of electrical outlets is a switched electrical outlet that can be turned on or off to selectively control the flow of electrical current therethrough.

[0093] In some embodiments, the at least one processor: identifying suspect electrical outlets corresponding to respective current characteristics; Switching the suspect electrical outlet to an OFF state; maintaining the suspect electrical outlet in an OFF state; upon determining that an external reset command or an administrator verification message has been received, switching the suspect electrical outlet to an ON state; The device is further configured to:

[0094] In some embodiments, the current characteristic represents the half-cycle root mean square (RMS) current or the peak current.

[0095]

[0095] Embodiments of the disclosed technology further provide a method of monitoring a plurality of electrical outlets of an electrical distribution apparatus, wherein each of the plurality of electrical outlets is adapted to supply power to an associated electronic device and includes an associated current sensor. As shown in Figure 10, method 1000 includes, at operation 1010, receiving a signal representative of a current from each associated current sensor.

[0096]

[0096] The method 1000 includes calculating a current characteristic of each associated current sensor based on the signal, at operation 1020. In one example, the signal is sampled and the current characteristic is determined based on the samples.

[0097]

[0097] The method 1000 includes, in operation 1030, detecting a trip event associated with at least one overcurrent protection device.

[0098]

[0098] The method 1000 includes, in operation 1040, determining whether at least one calculated current characteristic exceeds a selected threshold prior to detection of a trip event.

[0099] In some embodiments, method 1000 includes the acts of determining that each current characteristic exceeds a selected threshold prior to detection of a trip event, identifying a suspect electrical outlet corresponding to the each current characteristic, and providing a perceptible indication of the suspect electrical outlet on the electrical distribution device. In one example, the perceptible indication is provided on a display on the electrical distribution device. In another example, the perceptible indication is provided via one or more light emitting diodes (LEDs) on the electrical distribution device.

[0100] In some embodiments, the current characteristic represents the half-cycle root mean square (RMS) current. An example of the current sensor output and calculated half-cycle RMS is shown in Figure 11. In other embodiments, the current characteristic represents the peak current.

[0101] Those skilled in the art will appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, firmware, or combinations thereof. To clearly illustrate this interchangeability, the various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, software, and / or firmware depends on the particular application and design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

[0102] For 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 combinations thereof. For a firmware and / or software implementation, the methodologies may be implemented with modules (e.g., procedures, functions, etc.) that perform the functions described herein.

[0103] The foregoing description of the disclosed embodiments is provided to enable any 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 generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present invention. Thus, 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. 1. A power distribution device comprising: Housing and A power inlet and a plurality of electrical outlets, each of which (a) is adapted to supply power to an associated electronic device and (b) includes an associated current sensor; at least one overcurrent protection device; at least one processor coupled to the at least one overcurrent protection device and each associated current sensor; wherein the at least one processor: receiving a signal representative of current from each associated current sensor; calculating a current characteristic for each associated current sensor based on the signal; Detecting a trip event associated with the at least one overcurrent protection device; determining whether at least one calculated current characteristic exceeds a selected threshold prior to detection of said trip event; A power distribution device configured to:

2. Upon determining that the at least one calculated current characteristic exceeds the selected threshold, the at least one processor: Correlating the at least one calculated current characteristic to at least one of the respective associated current sensor or the respective associated current sensor's associated electronic device. The power distribution device of claim 1 further configured:

3. If the at least one processor determines that the respective current characteristic exceeds the selected threshold value prior to detection of the trip event, the at least one processor: identifying a suspect electrical outlet or a suspect electronic device at the suspect electrical outlet corresponding to the respective current characteristics; transmitting an identifier associated with the suspect electrical outlet to a location remote from the electrical distribution device; The power distribution device of claim 1 , further configured to:

4. If the at least one processor determines that two or more respective current characteristics exceed the selected thresholds prior to detection of the trip event, the at least one processor: identifying two or more suspect electrical outlets or suspect electronic devices of the two or more suspect electrical outlets corresponding to the two or more respective current characteristics; transmitting, to a remote location from the electrical distribution device, an identifier associated with one of the two or more suspect electrical outlets from which the highest value of the respective current characteristic was measured; and The power distribution device of claim 1 , further configured to:

5. the at least one processor: transmitting a waveform capture corresponding to the signal from at least one of the associated current sensors to the location remote from the power distribution device. The power distribution device of claim 3 further configured:

6. If the at least one processor determines that each of the respective current characteristics does not exceed the selected threshold, the at least one processor: transmitting a message from the electrical distribution device to a remote location indicating that none of the plurality of electrical outlets was an individual cause of the trip event; The power distribution device of claim 2 further configured as follows:

7. Further comprising a voltage sensor; The electrical power distribution apparatus of claim 1 , wherein detecting the trip event associated with the at least one overcurrent protection device is based on a signal representative of a voltage from the voltage sensor.

8. The electrical power distribution device of claim 1 , wherein calculating the current characteristic is based on sampling the signal from each associated current sensor.

9. 2. The electrical power distribution equipment of claim 1, wherein the trip event associated with the at least one overcurrent protection device corresponds to a voltage of at least one of the plurality of electrical outlets being less than a selected percentage or percentage range of a voltage of the power inlet.

10. 10. The electrical power distribution device of claim 9, wherein the selected percentage is 75%.

11. 10. The electrical power distribution device of claim 9, wherein the selected percentage range is from 65% to 85%.

12. 10. The electrical power distribution device of claim 1, wherein at least one electrical outlet of the plurality of electrical outlets is a switched electrical outlet that can be turned on or off to selectively control the flow of electrical current therethrough.

13. the at least one processor: identifying suspect electrical outlets corresponding to said respective current characteristics; switching the suspect electrical outlet to an OFF state; The power distribution device of claim 12 , further configured to:

14. the at least one processor: maintaining the suspect electrical outlet in the off state; upon determining that an external reset command or an administrator verification message has been received, switching the suspect electrical outlet to an ON state; The power distribution device of claim 13 , further configured to:

15. The power distribution device of claim 1 , wherein the current characteristic represents a half-cycle root mean square (RMS) current.

16. The power distribution device of claim 1 , wherein the current characteristic represents a peak current.

17. 1. A method for monitoring a plurality of electrical outlets of an electrical power distribution apparatus, each of the plurality of electrical outlets adapted to supply power to an associated electronic device and including an associated current sensor, the method comprising: receiving a signal representative of current from each associated current sensor; calculating, using at least one processor of the electrical distribution device, a current characteristic for each associated current sensor based on the signals; detecting, using the at least one processor, a trip event associated with at least one overcurrent protection device; using the at least one processor to determine whether at least one calculated current characteristic exceeds a selected threshold prior to detection of the trip event; A method comprising:

18. determining that a respective current characteristic exceeds the selected threshold value prior to detection of the trip event; identifying suspect electrical outlets corresponding to said respective current characteristics; providing a perceptible indication of the suspect electrical outlet on the electrical distribution device; 20. The method of claim 17, further comprising:

19. The method of claim 18 , wherein the perceptible indication is provided on a display on the electrical distribution device.

20. 20. The method of claim 18, wherein the perceptible indication is provided via one or more light emitting diodes (LEDs) on the electrical distribution device.

21. 18. The method of claim 17, wherein the current characteristic represents a half-cycle root mean square (RMS) current or a peak current.

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