Power distribution system and method

A backplane in a power distribution shelf has power outputs connected to corresponding primary card slots and adjacent card slots. Power distribution cards are seated in the card slots. A maintenance card can be configured to selectively provide redundant power to the power outputs of a failed power distribution circuit card via an adjacent power distribution circuit card and a maintenance connection.

This patent application generally relates to power distribution systems, and particularly relates to establishing redundant power distribution and facilitating maintenance operations in a communication system.

A communication system for providing voice, data and/or video communications to multiple subscribers may comprise a distribution unit and multiple remote network units. The distribution unit is centrally located, such as in a central office or in a roadside service cabinet, while the multiple remote network units are remotely located to provide voice, data and/or video communications to multiple subscribers. The remote units may receive both power and communication data from the distribution unit.

Often the distribution unit may comprise multiple power distribution circuit cards, each of which provides power to multiple remote network units. For example, each power distribution circuit card may provide power to eight remote network units, and the distribution unit may include 14 power distribution circuit cards, thus providing power to 112 remote network units. Each remote network unit, in turn, may service multiple subscribers.

Preventive maintenance and/or failure maintenance is required in all communication systems, during which service interruptions may occur. Because the distribution unit provides power to potentially multiple hundreds of subscribers, it is desirable to minimize service interruption to the fewest number of subscribers. Accordingly, disclosed herein are systems and methods for establishing redundant power distribution and for facilitating maintenance operations in a communication system.

DETAILED DESCRIPTION

FIG. 1is a block diagram of an example communication system. The communication system comprises a distribution unit10and a plurality of network units16-1. . . m. The distribution unit10may provide voice, data and/or video communications to each of the network units16-1. . . m, which, in turn, may provide voice, data and/or video communications to a plurality of corresponding subscribers S11-Smnvia corresponding cables19.

The distribution unit10includes a power distribution shelf12and a broadband distribution shelf14. The broadband distribution shelf14facilitates voice, data and/or video communications to and from the network units16-1. . . m via cables17, and the power distribution shelf12provides power to the network units16-1. . . m via cables18.

The communication system ofFIG. 1may be implemented in a fiber optic based network, in which voice, data and/or video communications are transmitted to and from optical network units16-1. . . m over fiber optic cables17. The optical network units16-1. . . m convert the optical communication data received from the broadband distribution shelf14into electrical communication signals and transmit the electrical communication signals to the corresponding subscribers S11-Smnover corresponding copper cables19. The copper cables19may include twisted pair cabling and coaxial cabling, or other copper-based communication wiring. The optical network units16-1. . . m also convert the electrical communication data received from the subscribers S11-Smninto optical communication signals and transmit the optical communication signals to the broadband distribution shelf14.

The power distribution shelf12provides power to the optical network units16-1. . . m via a corresponding plurality of conductors18. In the system shown inFIG. 1, each conductor comprises a source and return pair, and the power distribution shelf12is an extended reach power distribution shelf that provides a line voltage of −185 VDC over conductor pairs18. Previous optical communication systems provided a −140 VDC line voltage at the power distribution shelf12, and thus the distance between each network unit16and the distribution unit10was limited to approximately 65 VDC in line drop. By increasing the line voltage to −185 VDC, the maximum allowable distance between each network unit16and the distribution unit10is extended. For example, the power distribution shelf12may support a service area of approximately 7.1 Kft on 22 AWG wire at a load of approximately 35 W per optical network unit16. Lower line voltages, such as −140 VDC, may also be utilized, however.

FIG. 2is a block diagram of an example power distribution shelf12. An AC power source20is coupled to a rectifier22, which, in turn, produces a DC power output. In the example power distribution shelf12ofFIG. 2, the rectifier22produces −48 VDC power. A breaker panel24is configured to receive the −48 VDC power as input and outputs four power feeds25,26,27and28to a backplane60. A plurality of card slots S0-S14are configured to receive a plurality of power distribution circuit cards, which, in turn, receive the −48 VDC power signal from the four power feeds25,26,27and28and output the −185 VDC line voltage. Lower line voltages, such as −140 VDC, may also be output, however. The rectifier22, breaker panel24, and backplane16may all be attached to a power distribution shelf12chassis.

FIG. 3is a front view of the example power distribution shelf12. The example power distribution shelf12ofFIG. 3is fully populated with a power distribution circuit card30in each of the slots S0-S14. Each power distribution circuit card30includes a plurality of light emitting diodes (LEDs)32and a maintenance connector34. In the example fiber optic implementation described above, each power distribution circuit card30may comprise an optical network power unit30.

Each power distribution circuit card30is configured to receive the four power feeds25,26,27and28and source two power output channels from each power feed to provide eight power output channels. Accordingly, each power distribution circuit card30may provide power for up to eight optical network units16. Distributing the eight power output channels over the four power feeds25,26,27and28minimizes any output failures caused by a failure in one of the power feeds25,26,27and28to only two power output channels. Other power distribution schemes may also be used, such as a single power feed or further distribution of the power feeds to eight separate power feeds.

The LEDs32provide a visual readout of the current operational status of a corresponding power distribution circuit card30. The LEDs32may be configured to indicate whether a power output channel is enabled, disabled, or in a failure state. The LEDs32may be further configured to indicate other operational states and status of the power distribution circuit card30.

An alarm module40is connected to the backplane60of the power distribution shelf12and provides general indications that a failure has been detected in the power distribution shelf12. The alarm module40monitors the status of the power distribution circuit cards'30power output channels and classifies the failures according to a number of failures monitored. For example, LEDs42,44,46may be selectively energized to indicate a critical failure classification, a major failure classification, or a minor failure classification, respectively.

Failure monitoring may include summing the number of failed power output channels for all the power distribution circuit cards30. For example, if ten or more power output channels have failed, the LED42may illuminate to indicate a critical failure. If two to nine power output channels have failed, then the LED44may illuminate to indicate a major failure, and if only one power output channel has failed and/or other failures have occurred that do not impact subscriber service, then the LED46may illuminate to indicate a minor failure. Each alarm condition may be accompanied by an audible alarm.

Failure monitoring may alternatively include estimating the number of subscribers impacted by failed power output channels. For example, each optical network unit16may facilitate voice, data and/or video communications with up to 12 subscribers. Thus, the alarm module may be configured to classify failure states based on the estimated number of subscribers impacted due to power failures by equating each failed power output channel to 12 impacted subscribers. Additionally, by configuring the optical network units16to provide the actual number of subscribers serviced by each optical network unit16to the broadband distribution shelf14and providing this subscriber data to the alarm module40, the failure states may be classified by the actual number of impacted subscribers.

An alarm cut off LED48indicates whether an alarm cut off state has been activated. Activating the alarm cut off state may clear the audible alarm while not affecting the alarm LEDs42,44, and46. The alarm module40may be further configured to clear the alarm cut off state and activate the audible alarm if a new failure classification or new failure state occurs. For example, the alarm module40may be configured to clear the alarm cut off state and activate the audible alarm if a new failure classification occurs of the same or greater classification. Alternatively, the alarm module40may be configured to clear the alarm cut off state and activate the audible alarm for any new failure classification.

An alarm module connector50provides a data port for interfacing with the alarm module40. The alarm module connector50may be utilized to establish data communication with service equipment, such as a portable computing device utilized by a service technician. Alternatively, the alarm module40can also be connected to a system level control device which can relay alarm information to a network element manager.

Maintenance in response to the alarms reported by the alarm module40may require the replacement of a power distribution circuit card30, during which service interruptions may occur for subscribers receiving communication data from optical network units16powered by the power distribution circuit card30. Because each power distribution circuit card30may provide power to optical network units16that may collectively service 100 or more subscribers, it is desirable to minimize service interruption to the fewest number of subscribers.

To minimize such service interruptions, the backplane60is configured to facilitate maintenance operations by establishing electrical connections to utilize the power distribution circuit card30in slot S0as a maintenance card that provides a redundant power source. During normal operation, the power distribution circuit card30in slot S0does not provide power to optical network units16. During a maintenance operation, however, the power distribution circuit card30in slot S0is configured to provide power to the optical network units16associated with one of the other power distribution circuit cards30in slots S1-S14that is undergoing maintenance.

FIG. 4is a block diagram of the plurality of power distribution circuit cards30connected to the backplane60in the example power distribution shelf12. Slot S0defines a maintenance slot, and slots S1-S14define primary slots. The backplane60includes corresponding backplane power connections62for each of the card slots S1-S14, first power output connectors64and second power output connectors66associated with each of the card slots S0-S14, and backplane power connections68associated with the maintenance slot S0that define maintenance power connections68. The maintenance power connections68are connected to the first power output connectors74of the maintenance slot S0, and the backplane power connections62of other corresponding card slots S1-S14are connected to the first power output connectors64of their corresponding card slots and connected to the second power output connectors66of a corresponding adjacent card slot. Additionally, the maintenance power connections are connected to a cable70that terminates in a maintenance cable connector72that is configured to connect to any one of the maintenance connectors34of the power distribution circuit cards30.

In the example power distribution shelf12ofFIG. 4, card slots S0-S13define adjacent card slots for S1-S14, respectively. The adjacent relationship is established by connecting the first power output connectors64of a card slot to the second power output connectors66of another card slot. For example, as shown inFIG. 4, card slot S0is adjacent to card slot S1, and card slot S1is adjacent to card slot S2, etc.

Each of the power distribution circuit cards30comprise first connectors74and second connectors76. The first connectors74connect power output channels75that output DC power from the power circuitry84to the first power output connectors64in the backplane60. The power circuitry84receives the input power from the power feeds25,26,27and28and generates power output signals for the power output channels75. In the example power distribution shelf12ofFIGS. 1-4, the power feeds25,26,27and28provide −48 VDC input power and the power circuitry84generates a −185 VDC power signal for the power output channels75.

The second connectors76connect secondary power output channels77to the second power connectors66, thereby connecting the secondary power channels77to the backplane power connections62in an adjacent card slot. The secondary power output channels77receive power from the power distribution circuit card30in the maintenance slot S0during a maintenance operation and provide a temporary redundant power source for the backplane power connections62in an adjacent card slot, as explained below.

A processing subsystem80is in electrical communication with a data store82and the power circuitry84. The data store82is configured to store power configuration data that is used by the power circuitry84to selectively power the output channels75. The power configuration data may be used to indicate which power output channels75are to be energized. For example, if a power distribution circuit card30comprises eight power output channels and powers optical network units16on only two of the power output channels, then the power configuration data may indicate which two power output channels are to be energized. The power circuitry84may thus read the power configuration data to determine which two power output channels to selectively power.

The processing subsystem80is configured to communicate with other power distribution circuit cards30via the backplane60, to store and retrieve data into the data store82, and to operate the power circuitry84. Additionally, the processing subsystem80is also configured to generate an output disable signal to disable the power output channels75of an adjacent power distribution circuit card30during a maintenance operation.

During a maintenance operation, a power distribution circuit card30may need to be removed and repaired or replaced. When a particular power distribution circuit card30is removed, the power distribution circuit card30in the maintenance slot S0provides power to the backplane power connections62associated with the power distribution circuit card30that is being repaired or replaced.

To enable the power distribution circuit card30in the maintenance slot S0to act as a redundant power source, the maintenance cable connector72is connected to the maintenance connector34of the power distribution circuit card30adjacent to the failed power distribution circuit card30. For example, if the power distribution circuit card30in slot S3needs to be replaced, then the maintenance cable connector72is connected to the maintenance connector34of the power distribution circuit card30in slot S2. Upon connection of the maintenance cable70to the power distribution circuit card30, the power distribution circuit card30in the maintenance slot S0receives a maintenance cable connection signal. The power distribution circuit card30in slot S0then requests the slot identifier of the power distribution circuit card30to which the maintenance cable connector72is connected. For example, if the maintenance cable connector72is connected to the maintenance connector34of the power distribution circuit card30in slot S2, then the requested slot identifier is S2.

Upon receiving the requested slot identifier, the power distribution circuit card30in the maintenance slot S0requests the power configuration data of the power distribution circuit card30in the adjacent slot. For example, if the slot identifier received is S2, then the configuration data for slot S3is requested.

Upon receiving the configuration data for the power distribution circuit card30that has failed, the power distribution circuit card30in the maintenance slot S0energizes its power output channels75according to the configuration data and instructs the power distribution circuit card30in the adjacent slot to generate a disable signal to disable the power output channels75of the failed power distribution circuit card30. For example, upon receiving the configuration data for the power distribution circuit card30in slot S3, the power distribution circuit card30in slot S0will energize its power output channels75and instruct the power distribution circuit card30in slot S2to generate the disable signal.

The disable signal, in turn, causes the power distribution circuit card30in slot S3to disable its power output channels75. The backplane power connections62associated with slot S3, however, receive necessary power signals from the power distribution circuit card30in the maintenance slot S0. Therefore, the power output channels75of the power distribution circuit card30in slot S0are coupled to the power circuitry84of the power distribution circuit card30in the adjacent slot S2via the maintenance cable70and maintenance connector34. Through this connection, the power circuitry84of the power distribution circuit card30in the adjacent slot S2couples the power output channels75of the power distribution circuit card30in the maintenance slot S0to the backplane power connections62associated with slot S3via the secondary power output channels77, the second connectors76, and the second power connectors66. In this manner, the power distribution circuit card30in slot S3may be removed without affecting service to the optical network units16that receive power from the backplane power connections62of slot S3.

While the power circuitry84is shown as coupling the secondary power output channels77to the maintenance connector34, these channels77may also be directly connected to the maintenance connector34.

Once a replacement power distribution circuit card30is inserted into slot S3, the power distribution circuit card30in slot S0sends the stored configuration data to the newly inserted power distribution circuit card30. The replacement power distribution circuit card30in slot S3may then energize its power output channels75, and the maintenance cable70may be removed from the adjacent power distribution circuit card30in slot S2. Note that if the power distribution circuit card30in slot S1fails, the maintenance cable70may be connected to the maintenance connector34of the power distribution circuit card30in slot S0.

FIG. 5is an example power-up flow diagram100for a power distribution circuit card30. A power-up to energize the card circuitry is performed at102. Upon successful power-up, a determination of whether the power distribution circuit card30is in the maintenance slot S0is performed at104. Upon a positive determination, a reset of the power distribution circuit card30to a default configuration is performed at106and the and the power distribution circuit card30waits for a maintenance operation to commence. An example default configuration is placing all of the power output channels75in a disabled state.

If the power distribution circuit card30is not in a maintenance slot, it is determined at108if default configuration data is stored. Default configuration data may comprise a factory default setting, such as placing all the power output channels75in a disabled state. If default configuration data is not stored, it is determined at110if valid configuration data is stored. If valid configuration data is not stored, then at112an error process is performed.

If valid configuration data is stored, then it is determined at114if a disable signal from an adjacent power distribution circuit card30is present. The presence of a disable signal indicates that the power distribution circuit card30is being inserted as a replacement card. Thus, if a disable signal is present, then at116a request for configuration data from the power distribution circuit card30in the maintenance slot S0is issued. If a disable signal is not present, however, then the power channels75are enabled according to the stored configuration data.

Returning to108, if default configuration data is stored, then at120it is determined if a disable signal is present. If a disable signal is present, then at116a request for configuration data from the power distribution circuit card30in the maintenance slot S0is issued. If a disable signal is not present, however, then at122the power distribution circuit card30waits for enabling of the power output channels75. This latter function is typically performed when there is no configuration data available for a particular card slot, such as during an initial installation of the power distribution shelf12or reconfiguration of the power distribution shelf12by adding or removing optical network units16in the communication system10. In such situations the power distribution circuit card30may be manually configured by a technician.

FIG. 6is an example maintenance flow diagram130for the example power distribution shelf. The flow diagram130may be performed by the power distribution circuit card30in the maintenance slot S0in response to a reset of the power distribution circuit card30to a default configuration at106ofFIG. 5.

At132, the power distribution circuit card30in slot S0waits to receive a maintenance cable connect signal. Upon receiving the maintenance cable connect signal, the power distribution circuit card30in slot S0requests the slot ID of the power distribution circuit card30connected to the maintenance cable70, as shown at134. After receiving the slot ID, the power distribution circuit card30in slot S0requests the configuration data of the power distribution circuit card30in the adjacent slot (e.g., slot ID+1), as shown in136. Upon receiving the configuration data request, the power distribution circuit card30in the adjacent slot sends the configuration data to the power distribution circuit card30in the maintenance slot S0. At138, the received configuration data is stored in the power distribution circuit card30in slot S0and the power distribution circuit card30connected to the maintenance cable70is instructed to generate a disable signal to disable the power output channels of the power distribution circuit card30in the adjacent card slot.

At140it is determined whether the power distribution circuit card30in the adjacent slot is disabled. If the power distribution circuit card30in the adjacent slot is not disabled, then at142an error process is performed. If, however, the power distribution circuit card30in the adjacent slot is disabled, then at144the power distribution circuit card30in the maintenance slot S0enables its power channels75according to the configuration data received from the power distribution circuit card30in the adjacent slot. Power signals are provided to the backplane connections62associated with the adjacent slot via the maintenance cable70and the secondary power channels77. Accordingly, power is provided to the optical network units16associated with the failed power distribution circuit card30and the failed card may be removed and replaced without interrupting service to the associated optical network units16.

FIG. 7is an example configuration flow diagram150for a power distribution circuit card30. The flow diagram150may be performed by a power distribution circuit card30inserted into a card slot to replace a failed power distribution circuit card30.

At152it is determined if configuration data has been received from a power distribution circuit card30in the maintenance slot S0. If configuration data has not been received after a specified time period, then at154the power channels are enabled upon a manual configuration. If, however, configuration data has been received, then at156it is determined if the disable signal is low. If the disable signal is not low, then at158the power distribution circuit card30waits for the power distribution circuit card30in slot S0to instruct the adjacent card to negate the disable signal. Once the disable signal is negated, the power channels75are enable according to the configuration data at160.

FIG. 8is an example alarm monitoring flow diagram170for a power distribution shelf12. The flow diagram170may be performed by the alarm module40. At172the power output channels of the power distribution circuit cards30are monitored for failures, and at174the failures detected on the power output channels are summed. At176the power distribution circuit cards30are monitored for communication and other non-power output channel failures.

At178it is determined if the power output channel failures exceed a critical threshold. The critical threshold may correspond to the number of power output channel failures or the number of subscribers affected by the power output channel failures. If the critical threshold is exceeded, then a critical alarm signal is generated at180.

If the critical threshold is not exceeded, then it is determined at182if the power output channel failures exceed a major threshold. The major threshold may correspond to the number of power output channel failures or the number of subscribers affected by the power output channel failures. If the major threshold is exceeded, a major alarm signal is generated at184.

If the major threshold is not exceeded, then at186it is determined if any power output channels have failed, or if any communication or non-power output channel failures have occurred. If any power output channels have failed, or if any communication or non-power output channel failures have occurred, then a minor alarm signal is generate, otherwise an “OK” status is maintained at190.

FIG. 9is an example quiet front block configuration for a plurality of power distribution shelves12. The example configuration ofFIG. 9is designed for three 15-card shelves having 14 power distribution circuit cards30, each of which is configured to provide power to up to eight optical network units16. Each power distribution shelf12may also include a maintenance slot that is configured to receive a power distribution circuit card30for maintenance operations.

The quiet front blocks202,204,206,208,210,212,214and216each provide fifty terminal pairs that may be sequentially designated and are used to couple power channels75from the power distribution circuit cards30to a cross-connect for connection to corresponding optical network units16.

The quiet front blocks202,204,208,212,214and216are fully populated, while the quiet front blocks206and210are partially populated. The partial population of quiet front blocks206and210requires the termination of 13 terminal pairs, and may be better understood with reference toFIG. 10, which illustrates an example cabling scheme from the backplane of the power distribution shelves12a,12band12cto the quiet front blocks202,204,206,208,210,212,214and216. Each quiet front block202,204,206,208,210,212,214and216is configured to receive two standard 25-pair (50 conductor) cables. Because each power distribution shelf12a,12b, and12cmay provide power for up to 112 optical network units, 112 conductor pairs are required for each power distribution shelf12a,12b, and12c.

Given that a distribution unit10may include one or more power distribution shelves12, the backplanes60of the power distribution shelves12a,12b, and12care connectorized so that they may be placed in any shelf location in the distribution unit10. Accordingly, each power distribution shelf12a,12b, and12chas five 25-pair cables attached to the backplane60. For example, the backplane60of power distribution shelf12ahas 25-pair cables220a,222a,224a,226aand228a. Because only 112 conductor pairs are required, the remaining 13 pairs in the 25-pair cable228aare unused. This cabling scheme is repeated for power distribution shelves12band12c.

The quiet front blocks202,204,206,208,210,212,214and216may thus be readily connected to the connectorized backplanes60of the power distribution shelves12a,12band12cas shown inFIG. 10. Because the first 25 terminal pairs of the quiet front block206are connected to cable228a, the remaining 13 terminal pairs of the first 25 terminal pairs of the quiet front block206are unused. To facilitate ease of maintenance and avoid confusion, a terminal cover230may be attached to the partially populated quiet front block206to prevent access to the unused terminal pairs. The quiet front block210is configured in a similar manner, except that the remaining 13 terminal pairs of the last 25 terminal pairs are unused and covered by a terminal cover232.

The cabling scheme ofFIGS. 9 and 10facilitates a standardized manufacturing process for the power distribution shelves12a,12band12cand allows for ease of installation in the field. In the example configuration shown, the installing party need only attach a terminal cover to the remaining 13 terminal pairs of either the first 25 terminal pairs or second 25 terminal pairs of a partially populated quiet front block.

By terminating unused conductors in a terminal cable of a power distribution shelf (e.g., cables228a,228band228c) and not utilizing corresponding conductor pairs in a corresponding quiet front block (e.g., quiet front blocks206and210), the cabling scheme ofFIGS. 9 and 10can be modified to facilitate other standardized cabling and quiet front block configurations.