(12) United States Patent
`MeN ally et al.
`
`111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US006741442Bl
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,741,442 Bl
`May 25,2004
`
`(54)
`
`INTELLIGENT POWER DISTRIBUTION
`SYSTEM
`
`(75)
`
`Inventors: John McNally, Chicago, IL (US);
`Daniel Rohr, Fenton, MO (US)
`
`(73) Assignee: American Power Conversion
`Corporation, West Kingston, RI (US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 372 days.
`
`(21) Appl. No.: 09/688,298
`
`(22) Filed:
`
`Oct. 13, 2000
`
`Int. Cl? ................................................ HOlH 47/00
`(51)
`(52) U.S. Cl. .......................... 361/166; 361!191; 307/41
`(58) Field of Search ................................. 361/160, 166,
`361!167, 191-193; 307/29, 38, 39, 41,
`115, 125, 126, 141, 141.4, 143
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4,674,031 A * 6/1987 Siska, Jr. ..................... 700/79
`4,769,555 A * 9/1988 Pequet eta!. ............... 307/141
`4,970,623 A
`11/1990 Pintar
`5,071,367 A * 12/1991 Luu ........................... 439/501
`5,424,903 A * 6/1995 Schreiber .................... 361!166
`5,534,734 A * 7/1996 Pugh eta!. ................... 307/38
`5,721,934 A
`2/1998 Scheurich
`
`5/1999 Kao eta!.
`5,901,067 A
`5,923,103 A * 7/1999 Pulizzi eta!. ............... 307/126
`* cited by examiner
`Primary Examiner-Michael Sherry
`Assistant Examiner-Gary L. Laxton
`(74) Attorney, Agent, or Firm---Mintz, Levin, Cohn, Ferris,
`Glovsky and Popeo, P.C.
`ABSTRACT
`
`(57)
`
`An intelligent power distribution system including one or
`more intelligent power strips. The power strips can each
`include an elongated housing that may be adapted for
`mounting in an equipment rack. The housing can include a
`first end, a second end and plurality of power outlets
`mounted thereon. The first end can have a number of
`apertures that enable power and signal conductors to enter
`an interior region of the housing. The second end can include
`a first and a second communication port. The first commu(cid:173)
`nication port may be adapted to enable a computer to
`communicate with the power the strip. The second commu(cid:173)
`nication port may be adapted to enable the power the strip
`to be daisy chained with a second intelligent power strip.
`The power strip further includes power management cir(cid:173)
`cuitry that can power-on and power-off the power outlets in
`accordance with an operator defined sequence and delays.
`The power management circuitry can further sense electrical
`current drawn by the power strip and control operation of the
`power strip based on the sensed electrical current to mini(cid:173)
`mize branch circuit breaker tripping.
`
`26 Claims, 5 Drawing Sheets
`
`OUTLET RELAYS
`XB
`
`62b
`
`-------~-----------------------------------
`50
`
`68
`
`IPR Page 1
`
`Raritan v. Server Technology
`
`RARITAN EXHIBIT 1017
`
`

`
`U.S. Patent
`
`May 25, 2004
`
`Sheet 1 of 5
`
`US 6,741,442 B1
`
`IPR Page
`
`IPR Page 2
`
`

`
`U.S. Patent
`
`May 25, 2004
`
`Sheet 2 of 5
`
`US 6,741,442 B1
`
`IPR Page
`
`IPR Page 3
`
`

`
`U.S. Patent
`
`May 25,2004
`
`Sheet 3 of 5
`
`US 6,741,442 Bl
`
`12
`
`Fig. 3
`
`IPR Page 4
`
`

`
`U.S. Patent
`
`May 25,2004
`
`Sheet 4 of 5
`
`US 6,741,442 Bl
`
`AC
`POWER ~,80
`SOURCE
`
`• CIRCUT
`
`54-.......
`
`1
`1
`1
`
`18b OUTL~:ELAYS
`
`56
`
`760 _r ON/OFF
`
`BREAKER
`82
`-------------------------------------
`52
`,---. OUTLET "
`)
`x8
`1 '--18a
`r - - CURRENT
`SENSOR
`OUTLET
`+
`f
`L - ~ RELAY
`15
`24VDC/
`~~~~~J'~Plv ~58
`'---.....,....---1
`\
`.._~I OUTLET STATE I
`l
`l ~ 60a
`LED
`I
`24VDC-I
`61 L-::~~~~~==~_J
`12VDC svoc 24VOC
`INPUT POWER ~Ob
`-(,
`[ RELAY DRIVER
`76.
`SOURCE ~ 24VDCEx I
`SENSOR
`1
`t--r60c
`.(
`62a_r
`60
`: POWER
`OVERLOAD
`1 SOURCE
`~D
`_,.__
`t
`78
`
`STATE
`
`62
`-(_
`M~~
`CONTROLLER
`
`1
`
`1-
`
`UNDERVOLTAGE
`SENSOR
`
`RESET
`~
`62c
`~--+l NON-VOLATILE
`MEMORY
`T~ .-----.. ~
`70
`~----=---=-----.~
`Rx2
`COMNt
`OUT
`
`~b
`
`I
`I
`I
`I
`I
`
`64aJ COMM.
`IN
`
`IRMS
`
`Rxl
`Tx1
`
`I
`6'
`•
`I AUDIBLE ALARM I
`:;
`
`t
`I
`r MUTE l
`BUTTON
`\
`68
`- - - - - - - - - - - - - - - - - -
`Fig. 4
`
`- - - - - - - - ~- -
`so
`
`- - -
`
`- - - - - - - - - - - - ....
`
`IPR Page 5
`
`

`
`U.S. Patent
`
`May 25,2004
`
`Sheet 5 of 5
`
`US 6,741,442 Bl
`
`ENERGIZE POWER STRIP
`TO POWER-ON A FIRST
`GROUP OF OUTLETS
`
`110
`
`SELEOlVELY POWERING
`ON A SECOND GROUP
`OF OUTLETS
`
`130
`
`SENSING CURRENT
`ON AN INPUT
`POWERUNE
`
`t-----t-<
`
`NO
`
`YES
`
`(
`
`100
`
`YES
`
`180
`
`SELECTIVELY POWERING-
`OFF NON-ESSENTIAL
`OUTLETS
`
`CONTROL OVERLOAD
`LEDTO.FLASH GREEN
`200
`
`190
`
`230
`
`SELECTIVELY POWERING-
`OFF ADDITIONAL
`NON-ESSENTIAL OUTLETS
`
`210
`
`240
`
`220
`
`CONTROL OVERLOAD
`LED TO ILLUMINATE
`RED
`
`SELECTIVELY
`POWERING OFF
`THE SECOND
`GROUP OF
`OUTLETS
`
`POWERING OFF
`THE FIRST
`GROUP OF
`OUTLETS
`
`Fig. 5
`
`IPR Page 6
`
`

`
`US 6,741,442 Bl
`
`1
`INTELLIGENT POWER DISTRIBUTION
`SYSTEM
`
`FIELD OF THE INVENTION
`
`5
`
`2
`Therefore, a need exists for an intelligent power distri(cid:173)
`bution system that can provide power up and/or power down
`sequences and delays for equipment, which overcomes
`limitations and deficiencies of the prior art.
`
`SUMMARY OF THE INVENTION
`
`The present invention generally relates to an intelligent
`power distribution system and method, and more particu(cid:173)
`larly to an intelligent power strip and method of distributing
`power in an electronic system.
`
`BACKGROUND
`
`Many electronic and electrical systems, such as computer
`and home entertainment systems, require that electrical
`power be applied to components of the system according to
`a particular sequence to avoid causing undue stress and 15
`possible damage to the components. Particularly with com(cid:173)
`puter systems, there are many situations in which it is
`advantageous to delay activation of peripheral devices until
`after the parent device is powered up and has attained a
`quiescent state. A typical situation is that of a personal or 20
`business computer system where the activation of peripheral
`devices including a monitor, disk drives and printers, are
`delayed until after the computer itself is fully on-line. Upon
`activation of the parent device and after the parent device
`reaches a quiescent operating state, power can be applied to 25
`the peripheral devices. This sequence of powering up a
`computer system is especially helpful in eliminating unde(cid:173)
`sirable transient currents and random logic states caused by
`simultaneous power up of the parent and peripheral devices.
`For example, in many computer systems, power is first
`applied to the computer itself before power is applied to the
`monitor, because the computer supplies the monitor with
`horizontal and vertical synchronization pulses necessary to
`prevent the free running of the monitor's horizontal and 35
`vertical oscillators. Allowing the oscillators to operate in an
`unsynchronized condition can result in undue stress to the
`oscillators and hard failure of the monitor.
`Similarly, power is applied to the computer before power
`is applied to the printer. Otherwise, the printer can poten(cid:173)
`tially back-feed power or control signals to the computer and
`cause the computer to fail to initialize when the computer
`subsequently receives power. Consequently, the order and
`timing of the application of power to and removal of power
`from certain systems needs to be carefully controlled so as
`to avoid damaging the system components.
`One solution for providing power to systems similar to
`that described above includes employing an operator to
`manually turn on the components. Specifically, the operator
`can power on the computer itself and pause momentarily to
`allow sufficient time for the computer to reach a quiescent
`operating state before providing power to the computer's
`peripheral devices. This method is generally unsatisfactory,
`because the time delay interval is difficult to control and
`duplicate manually, and further, because it may be desirable
`to ensure that the power up and power down of the system
`always occur according to a particular sequence.
`Another solution is to use time delay relays ("TDRs") to
`provide a predetermined, fixed time delay between applica(cid:173)
`tion of power to one component and the next. This method
`is also unsatisfactory, as well as being very expensive. TDRs
`are capable only of providing a fixed, or at best, a narrowly
`adjustable, time delay. Furthermore, the power up delay is
`typically equal to the power down delay, a condition which
`may be undesirable in certain cases. Finally, the time delay 65
`provided by the TDRs is typically not easy to adjust by an
`operator.
`
`30
`
`It is an object of the present invention to provide an
`intelligent power distribution system and method for using
`the power distribution system. In embodiments of the
`10 present invention, the intelligent power distribution system
`can manage power consumption to minimize tripping of a
`branch circuit breaker which provides electrical power to the
`system.
`In one aspect of the present invention, a power distribu(cid:173)
`tion system can include a plurality of intelligent power strips
`that can be adapted for mounting in an equipment rack. The
`power strips can be individually mounted and controlled or
`the power strips can be daisy chained together to form a
`scalable power strip which can be unitarily controlled. The
`equipment rack can have a number of slots that may be
`adapted to securely hold a number of pieces of equipment
`thereon.
`Each intelligent power strip can include a housing that has
`a first end and a second end. A plurality of power outlets can
`be mounted on an exterior surface of the housing to provide
`power to the equipment. An aperture can be formed on the
`first end of the housing to enable power and signal conduc(cid:173)
`tors to access an interior region of the housing. A first
`communication port and a second communication port can
`be defined on the second end of the housing. The first
`communication port can include a communication-in circuit
`that enables bi-directional communication with the power
`strip and the second communication port can include a
`communication-out circuit that enables the power strip to be
`coupled to a second power strip.
`The intelligent power strip can further include a power
`management circuit which is defined in the interior region of
`the housing. The power management circuit can include a
`40 current sensor circuit that may be adapted to receive alter(cid:173)
`nating current ("AC") input power over an AC input power
`line. The current sensor circuit can be coupled to the power
`outlets as well as to an AC to direct current ("DC") power
`supply. The AC to DC power supply receives and processes
`45 AC power from the current sensor circuit to generate a
`plurality of DC voltage values.
`The micro-controller can be coupled to the power supply
`and can receive one or more voltage values from the power
`supply. The micro-controller may be further coupled to a
`50 relay driver. The relay driver can receive control signals
`from the mica-controller to control a plurality of relays
`coupled to the relay driver. The relays can be coupled to the
`power outlets defined on the housing of the power strip. The
`relays can be controlled to a conductive state to power-on
`55 the power outlets and the relays can be controlled to a
`non-conductive state to power-off the power outlets.
`The power outlets defined on the power strip can include
`a first group of power outlets and a second group of power
`outlets. The first group of power outlets can be coupled to
`60 the sensor circuit and the second group of power outlets can
`be coupled to the sensor circuit via the relays. The second
`group of power outlets can each include a light-emitting(cid:173)
`diode ("LED") that can be controlled to illuminate to
`indicate that each power outlet is powered-on.
`The power management circuit can further include an
`input power source sensor circuit. The input power source
`sensor circuit can be coupled intermediate the power supply
`
`IPR Page 7
`
`

`
`US 6,741,442 Bl
`
`4
`normal-threshold value and below the overload-threshold
`value, the method further includes indicating a high current
`status of the power distribution system.
`The method can further include determining if the sensed
`5 current is above the overload-threshold value. If the sensed
`current is determined to be above the overload-threshold
`value, the method further includes indicating an alarm status
`of the power distribution system.
`If the sensed current is determined to be above the
`10 normal-threshold value and below the overload-threshold
`value, the method further includes controlling a first group
`of predetermined relays to actuate to a non-conductive state
`to power-off a number of associated power outlets.
`If the sensed current is determined to be above the
`overload-threshold value, the method further includes con(cid:173)
`trolling a second group of predetermined relays to actuate to
`a non-conductive state to power-off a number of associated
`power outlets.
`The method can further include controlling the plurality
`of relays to actuate to a non-conductive state in accordance
`with a predetermined sequence to sequentially power-off the
`second group of power outlets, which are coupled to the
`relays; and de-energizing the input power line defined on the
`25 power distribution system to power-off the first group of
`power outlets defined on the power distribution system.
`
`20
`
`3
`and the micro-controller. The input power source sensor
`circuit can receive DC input power from the power supply
`that is hereinafter defined as primary DC input power, which
`can be provided to the micro-controller. The input power
`source sensor circuit can further receive secondary DC input
`power from a secondary power source. The secondary power
`source can be provided by the communication-in circuit and
`can provide a redundant power source for the mica(cid:173)
`controller. In the event that the primary DC input power
`provided by the power supply fails or is unavailable, the
`input power source sensor circuit can provide the secondary
`DC input power to the micro-controller.
`The micro-controller can be further coupled to an under
`voltage sensor. The under voltage sensor can be adapted to
`receive a predetermined voltage value from the power 15
`supply. The under voltage sensor can be responsive to the
`predetermined voltage value falling below a predetermined
`threshold value by providing a reset signal to the micro(cid:173)
`controller. The predetermined threshold value can be defined
`by a user of the intelligent power distribution system.
`A non-volatile memory device can also be coupled to
`micro-controller to enable the micro-controller to store
`initialization and configuration information as well as other
`operating parameters.
`The micro-controller can also be coupled to an audible
`alarm that can alert an operator that current on the input
`power line has exceeded a predetermined threshold value. A
`mute button coupled to the micro-controller can be actuated
`to silence the audible alarm.
`An overload LED, which is coupled to the micro(cid:173)
`controller, can be controlled to illuminate with a predeter(cid:173)
`mined frequency to indicate an overload status of the input
`power line.
`In another aspect of the present invention, a power 35
`distribution method includes energizing an input power line
`to power-up a first group of power outlets on a power
`distribution system; and controlling a plurality of relays to
`actuate to a conductive state in accordance with a predeter(cid:173)
`mined sequence and predetermined delay to sequentially 40
`power-on a second group of power outlets defined on the
`power distribution system. Powering-on the second group of
`power outlets further includes illuminating a light-emitting(cid:173)
`diode associated with each power outlet, defined in the
`second group, to indicate a powered-on status of the second 45
`group of power outlets.
`Initializing the power distribution system can include
`programming a normal-threshold value into the power dis(cid:173)
`tribution system; programing an overload-threshold value
`into the power distribution system; programming an under- 50
`voltage threshold value into the power distribution system;
`programming delays into the power distribution system, the
`delays can be related to powering-on and powering-off
`power outlets defined in the second group; and programming
`the sequence for which power outlets can be powered-on 55
`and powered-off.
`The method can further include sensing current on the
`input power line; providing the sensed current to a micro(cid:173)
`controller; and determining if the sensed current is below the
`normal-threshold value. If the sensed current is determined 60
`to be below the normal-threshold value then the method
`further includes indicating a normal operating status of the
`power distribution system.
`The method can further include determining if the sensed
`current is above the normal-threshold value; and determin- 65
`ing if the sensed current is below the overload-threshold
`value. If the sensed current is determined to be above the
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other objects of this invention, the
`30 various features thereof, as well as the invention itself, can
`be more fully understood from the following description
`when read together with the accompanying drawings in
`which:
`FIG. 1a is an intelligent power strip in accordance with an
`embodiment of the present invention;
`FIG. 1b is another view of the intelligent power strip
`shown in FIG. 1;
`FIG. 2a is an enlarged view of a portion of the intelligent
`power strip shown in FIG. 1;
`FIG. 2b is an enlarged view of another portion of the
`intelligent power strip shown in FIG. 1;
`FIG. 3 is a power distribution system which includes the
`intelligent power strip shown in FIG. 1;
`FIG. 4 is a schematic block diagram of power manage(cid:173)
`ment circuitry which is included in the intelligent power
`strip shown in FIG. 1; and
`FIG. 5 is a flow chart showing a method of using the
`power strip shown in FIG. 1.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`In the following detailed description of the present inven(cid:173)
`tion numerous specific details are set forth in order to
`provide a thorough understanding of the present invention.
`However, it will be obvious to one skilled in the art that the
`present invention may be practiced without these specific
`details. In other instances, well known methods, procedures,
`components, and circuits have not been described in detail
`as not to unnecessarily obscure aspects of the present
`invention.
`In accordance with an embodiment of the present
`invention, an intelligent power strip is set forth that can
`provide electrical power and power management to one or
`more computer systems and their related peripheral devices.
`The power strip includes internal power management cir-
`
`IPR Page 8
`
`

`
`US 6,741,442 Bl
`
`15
`
`20
`
`25
`
`5
`cui try and external power outlets. The intelligent power strip
`can operate in conjunction with power management
`procedures, within the scope of the present invention, to
`provide a power management system for conventional com(cid:173)
`puter systems. The power management system may be
`implemented on a general purpose computer system to
`provide that computer system with automatic and/or user
`programmable power management features.
`Referring to FIGS. 1a, 1b, 2a, 2b and 3, in one specific
`embodiment, the intelligent power strip includes an elan- 10
`gated rectangular housing 12, which has a first end 14 and
`a second end 16. The housing 12 can further include a
`plurality of externally accessible AC power outlets 18,
`through which one or more computers 20 and their related
`peripherals 22 receive power. The power outlets 18 can be
`mounted along a longitudinal length of one face of the
`housing 12. A number of mounting brackets 24 can be
`coupled to the housing 12 to enable the housing to be
`mounted to an equipment rack 41 as shown in FIG. 3. The
`first end 14 of the housing 12 can include a number of
`apertures 14 which may be adapted to permit power and
`signal conductors to enter an internal region of the housing
`12. The second end 16 of the housing 12 can include a
`plurality of externally accessible communication ports 26. In
`an embodiment, a first communication ports 26a is adapted
`to permit an external control device, such as computer
`system 20, to communicate with the power management
`circuitry 50 (FIG. 4) defined in the housing 12. A second
`communication port 26b, defined on the second end 16 of
`the housing 12, is adapted to permit the power management
`circuitry 50 to communicate with one or more external
`devices. The external devices may be one or more intelligent
`power strips 10, which can be daisy chained together.
`In an embodiment, a power distribution system 40 can
`include a plurality of power strips 10 which may be indi- 35
`vidually operated or which may be daisy chained together as
`previously described. The power strips can be mounted in
`the equipment rack 41. The equipment rack 41 can include
`a number of slots 42, which are adapted to securely hold a
`number of pieces of equipment (not shown) thereon.
`Referring further to FIG. 4, the power management cir(cid:173)
`cuitry 50, which is positioned in the interior region of the
`housing 12 of the power strip 10, includes a current sensor
`circuit 52. The current sensor circuit 52 receives AC input
`power over an AC input power line 54 from an AC power 45
`source 80 through branch circuit breaker 82.
`The power outlets 18 defined on the power strip can
`include a first group of power outlets 18a and a second group
`of power outlets 18b. The first group of power outlets 18a
`can be coupled to the current sensor circuit and can be
`defined as constant power outlets. The first group of power
`outlets 18a can remain energized as long as power is
`provided to the power strip 10 by the AC power source 80
`over input power line 54. Each outlet, defined in the second
`group of power outlets 18b, can be coupled to the current 55
`sensor circuit via an associated relay 56. The second group
`of power outlets 18b can remain energized as long as the
`relay 56 associated with each outlet is actuated to a con(cid:173)
`ductive state.
`The current sensor circuit 52 is further coupled to an AC
`to DC power supply 58 which can provide a plurality of DC
`voltage values to power other components of the power strip
`10. The AC to DC power supply 58 can be coupled to an
`input power source sensor circuit 60 which is further
`coupled to a micro-controller 62.
`The input power source sensor circuit 60 is adapted to
`receive primary DC input power over power line 60a from
`
`6
`the AC to DC power supply 58. The input power source
`sensor circuit 60 is further adapted to receive secondary DC
`input power from a secondary source 61. The secondary
`source can include a DC power line 60c provided by the
`5 communication-in circuitry 64a, which will be described in
`further detail below. In an embodiment, the primary and
`secondary DC input power can include a 24-volt DC input
`voltage level.
`The input power source sensor circuit 60 normally oper-
`ates from the primary DC input power, which is provided by
`the AC to DC power supply 58. The input power source
`sensor circuit 60 further provides the primary DC input
`power to the micro-controller 62 over line 62a. However, in
`the event of a failure of the AC to DC power supply 58, the
`secondary DC input power can be provided by the input
`power source sensor circuit 60 to power the micro-controller
`62. In this configuration, the micro-controller 62 can be
`redundantly powered by either the primary DC input power
`or the secondary DC input power via the input power source
`sensor circuit 60.
`The input power source sensor circuit 60 can further
`include circuitry to determine if the input power source
`sensor circuit 60 is providing power to the micro-controller
`62 from the primary or secondary DC input power. In the
`event that the input power source sensor circuit 60 deter(cid:173)
`mines that it is providing the secondary DC input power to
`the micro-controller, the input power source sensor circuit
`60 can communicate with the operator, via the
`communication-in circuit 64a, to notify the operator that the
`AC to DC supply 58 has failed.
`In one embodiment, the micro-controller 62, which is
`incorporated in the power management circuitry 50, is a
`model XA, PXAG49KBA, which can be obtained from
`Philips, Amsterdam, Netherlands. The micro-controller 62
`can receive a sense current signal from the current sensor
`circuit 52 over line 62b, which represents a proportionate
`level of current that is drawn by the power strip 10 over the
`input power line 54.
`The micro-controller is further coupled to the
`communication-in circuit 64a and the communication-out
`64b circuit. The communication-in circuit 64a and the
`communication-out circuit 64b are respectively coupled to
`the first 26a and second 26b communication ports, which are
`defined on the external region of the second end 16 of the
`housing 12. In an embodiment, the communication-in circuit
`64a and the communication-out circuit 64b can each include
`an RS232 communication device. The RS232 communica-
`tion devices associated with the communicate with circuit
`50 64a and the communication-out circuit 64b can each
`bi-directionally communicate with the mica-controller 62
`over their respective communication lines Tx1, Rx1 and
`Tx2, Rx2.
`The micro-controller 62 is ether coupled to an audible
`alarm 66 and a mute button 68. The audible alarm 66 alerts
`an operator, via a speaker 13 (FIG. 2b) mounted on the
`housing 12, of electrical current on the input power line 54
`that exceeds a predetermined threshold value. The operator
`can silence the alarm 66 by actuating the mute button 68.
`60 The micro-controller 62 is also coupled to a non-volatile
`memory 70, such as an electrically-erasable-programmable(cid:173)
`read-only-memory ("EEPROM"). The non-volatile memory
`70 can store configuration information as well as power
`management operating instructions.
`An under-voltage sensor circuit 72 is coupled to the
`micro-controller 62 and can provide a reset signal to the
`micro-controller 62 over line 62c. More specifically, the
`
`30
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`40
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`IPR Page 9
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`US 6,741,442 Bl
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`7
`under-voltage sensor circuit 72 is adapted to receive a 5-volt
`value from the AC to DC supply 58. The under-voltage
`sensor circuit 72 compares the 5-volt value to a predeter(cid:173)
`mined threshold value. If the 5-volt value falls below the
`predetermined threshold value a reset signal is provided by 5
`the under-voltage sensor circuit 72 to the micro-controller
`62 over line 62c.
`For example, the predetermined under-voltage threshold
`value can be programmed to 4.6-volts. Thus, if the 5-volt DC
`voltage provided to the under-voltage sensor circuit 72 by
`the power supply 58 falls below the under-voltage threshold
`value of 4.6-volt, a reset signal will be provided to the
`micro-controller 62 over line 62c. The reset signal can reset
`the micro-controller 62 or maintain the micro-controller 62
`at an idle state until the AC to DC supply 58 provides the
`under-voltage sensor circuit 72 with a voltage value that 15
`exceeds the threshold value or which exceeds the threshold
`value of 4.6-volts in this example. Maintaining the micro(cid:173)
`controller in an idle state, when the 5-volt value provided by
`the AC to DC power supply is below the threshold, mini(cid:173)
`mizes the micro-controller entering a random logic state.
`The micro-controller 62 is further coupled to a relay
`driver circuit 76. The relay driver circuit 76 is coupled to
`each relay 56 associated with each of the power outlets 18b.
`Additionally, the relay driver circuit 76 can provide a control
`signal to each relay 56, which is associated with each power 25
`outlet 18b, to power-on and power-off each power outlet
`18b. More precisely, each relay 56 can be individually
`actuated between a conductive state and a non-conductive
`state for controllably providing power to each power outlet
`18b that is associated with each relay 56. Each power outlet 30
`18b can include an LED 15 that can be controlled to
`illuminate to indicate to an operator that a particular power
`outlet 18b is powered-on.
`An over load LED 78 can be coupled to the micro(cid:173)
`controller 62. The over-load LED 78 can be controlled to
`illuminate or flash at a predetermined frequency to indicate
`the operating status of the intelligent power strip 10 to an
`operator. In one example, the overload LED 78 can be
`controlled to illuminate a green light when the current drawn
`over input power line 54 is under a predetermined normal(cid:173)
`threshold value. The overload LED 78 can also be controlled
`to illuminate a green flashing light when the current drawn
`over input power line 54 is over the normal-threshold value,
`but below a predetermined overload-threshold value. The
`overload LED 78 can be further controlled to illuminate a
`red light when the current drawn over input power line 54
`has exceeded the overload-threshold value.
`Referring further to FIG. 5, a method of operating the
`intelligent power strip 100 can include an operator
`powering-on the first group of power outlets 18a by apply(cid:173)
`ing AC power to the input power line 54 at step 110.
`Immediately after applyingAC power to theAC input power
`line 54, the first group of power outlets 18a can be powered(cid:173)
`on to energize one or more computers 20 or peripheral
`devices 22 coupled therewith. After applying AC power to
`the power strip 10, the power strip 10 can be initialized at
`step 120. In initializing the power strip 10 at step 110, the
`operator can program the power strip 10 with a number of
`system parameters and operating configurations. The system
`parameters and operating configurations can include: a
`normal-threshold value, an overload-threshold value, an
`under-voltage threshold value, delays related to powering(cid:173)
`on and powering -off the second group power outlets 18b and
`the sequence for which power outlets 18b can be powered(cid:173)
`on and powered-off.
`After initializing the power strip at step 120, the second
`group of power outlets 18b can be selectively powered-on at
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`8
`step 130. The second group of power outlets 18b can be
`selectively powered-on, at step 130, in accordance with the
`operator defined sequence and operator defined delays.
`Similarly, one or more computers 20 and/or peripheral
`devices 22, which can be coupled to the second group of
`power outlets 18b can also be powered-on in accordance
`with the sequence and delays.
`After the step of powering -on the second group of outlets
`at step 130, the method of operating the intelligent power
`10 strip further includes sensing current on the power input line
`54, at step 140, with the current sense circuit 52. The current
`values sensed by the current sense circuit 52 are provided to
`the micro-controller 62 to enable the micro-controller 62 to
`determine if the normal-threshold value or the overload-
`threshold value has been exceeded. At step 150, if it is
`determined that the sensed current on the input power line 54
`is below the normal-threshold value, normal operation can
`continue at step 160. If the micro-controller 62 determines
`that the current on input power line 62 has exceeded the
`20 normal-threshold value at step 150, but is still below the
`overload-threshold value, as determined at step 170, the
`micro-controller can provide a control signal over line 76a
`to instruct the relay driver 76 to actuate one or more relays.
`At step 180, the relays 56 can be actuated to a non-
`conductive state to power-off one or more associated power
`outlets 18b and associated equipment. At step 190, the
`mica-controller can further control the overload LED 78 to
`flash a green light to indicate the overload status of the
`power strip 10.
`At step 170, if it is determined that the sensed current on
`the input power line 54 has exceeded the overload-threshold
`value, the micro-controller 62 can provide another control
`signal over line 76a to instruct the relay driver 76 to actuate
`additional relays 56. At step 200, the additional relays 56 can
`35 be actuated to a non-conductive state to power-off additional
`power outlets 18b as well as associated connected loads. In
`this manner, one or more power outlets 18b can be powered(cid:173)
`off depending on the curre