Abstract:
Methods and apparatuses are used for AC and DC electric power systems. The apparatus according to one embodiment is a pin system ( 180 A) for AC and DC electric power systems which comprises a female pin ( 418 ), the female pin ( 418 ) comprising a resistive region ( 405 ), the resistive region ( 405 ) forming a first portion of an inner surface of the female pin ( 418 ), and a conductive region ( 406 ), the conductive region ( 406 ) forming a second portion of the inner surface of the female pin ( 418 ), the conductive region ( 406 ) contacting the resistive region ( 405 ), the conductive region ( 406 ) being located further than the resistive region ( 405 ) from an open end of the female pin ( 418 ); and a male pin ( 415 ) adapted to be inserted in the female pin ( 418 ) along the inner surface of the female pin ( 418 ), the male pin ( 415 ) being made of a conductive material.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This non-provisional application is related to co-pending non-provisional applications titled “Method and Apparatus for Hot Swap of Line Replaceable Modules for AC and DC Electric Power Systems” and “Method and Apparatus for Integrated Active-Diode-ORing and Soft Power Switching”, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to connector pin systems, and more particularly to a method and apparatus for hot swap of modules using connector pin systems. 
         [0004]    2. Description of the Related Art 
         [0005]    Electric systems used in complex environments such as aerospace systems, more electric aircraft systems, industrial environments, vehicles, etc., include a large number of electric modules. Various electric modules may need to be extracted and replaced with other electric modules, to change functionality or to replace electric modules that exhibit faults. 
         [0006]    Hot swap, hot-plug, and hot-dock are terms used interchangeably to refer to the process of safely inserting or removing cards, PC boards, cables, and/or modules from a host system without removing power. The goal of hot swap is to insert or remove modules without disturbing, damaging, or degrading up/down-stream adjacent line replaceable modules/subsystems, to increase system availability, reduce down time, simplify system repair, and allow for system maintenance/upgrade without interrupting service to other loads. 
         [0007]    If not designed for properly, hot swap can cause severe electrical, mechanical, thermal and operational problems in an electrical system. For example, random pin arcing may occur during the mating process of a replaceable module with its parent electrical system. Pulling a board/module out while there is current passing through the module connectors, or inserting a board/module with all bulk/bypass capacitors at zero volts, can introduce severe electrical voltage/current transients which may adversely impact reliability and lead to safety consequences. For example, current chopping introduces Ldi/dt variations (where L is inductance of a load, for example) leading to very large voltage transients which are a major safety concern for maintenance people, as large voltage transients can cause high voltage electrical shock. 
         [0008]    Multiple long/short pin arrangements are used in typical/conventional hot swap of replaceable modules. One such pin arrangement is described in “ Introduction to Hot Swap ”, by Jonathan M. Bearfield, Texas Instruments, TechOnLine, publication date Sep. 24, 2001. In this publication, a hot swap system for hot swap of modules includes a connector with long and short pins, a fuse, and an RC circuit. During hot swap of a module, the long pins mate first, adding the RC circuit to pre-charge the module/board. When the board/module is fully inserted, the short pins mate, bypassing the resistor connected to the longer pins and creating a low impedance connection. One problem associated with long/short pin arrangements is the increase in number of pins needed for hot swap. Presence of more pins for hot swap leads to increased cost and weight of systems using such hot swap pin arrangements. A second problem associated with long/short pin arrangements for hot swap is lack of control in the timing of pin insertion and extraction during hot swap. 
         [0009]    Some techniques to integrate long and short pins have been studied. One such technique is described in U.S. Pat. No. 4,747,783 titled “ Resistive Pin for Printed Circuit Card Connector ”, by P. D. Bellamy et al. In the technique described in this patent, a male connector pin is made of a conductive material, an outer layer of resistive material, and a layer of insulating material. The outer layer of resistive material is deposited on a first portion of the conductive material. The insulating layer separates the resistive layer from the conductive material. As the pin is inserted into an electrical socket, socket contacts travel first along the resistive portion of the pin, and then along the conductive portion of the pin. In this technique, however, the length of the socket-contacted resistive region of the pin increases to a maximum, before the socket contacts reach the conductive region of the pin. Hence, the resistance of the connector pin increases to a maximum, after which abruptly drops to zero, which leads to a non-uniform and not well controlled hot swap process. Moreover, a pin system as described in the above mentioned patent is difficult to manufacture and is not cost-effective, due to the configuration of layers on the pin connector. 
         [0010]    A disclosed embodiment of the application addresses these and other issues by utilizing an integrated hot swap connector pin system that includes a conductive male pin, and a female pin with a resistive region, an insulating region, and a conductive region. The method and apparatus produce a gradually decreasing resistance as the male pin is inserted into the female pin, hence eliminating in-rush currents during hot swap insertion of a replaceable module into a live power board. The method and apparatus produce a gradually increasing resistance as the male pin is extracted from the female pin, hence reducing current chopping during hot swap extraction of a replaceable module from a live power board. The method and apparatus prevent random pin arcing during mating process by reducing the AC or DC current during the MAKE or BREAK process; eliminate in-rush currents during initial insertion of a board/module with all bulk/bypass capacitors at zero volts; eliminate large electrical voltage/current transients, such as large voltage transients due to Ldi/dt current chopping variations, which may adversely impact reliability and lead to safety consequences; provide a uniform and well controlled hot swap of replaceable modules and boards. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention is directed to methods and apparatuses for AC and DC electric power systems. According to a first aspect of the present invention, a pin system for AC and DC electric power systems comprises: a female pin, the female pin comprising a resistive region, the resistive region forming a first portion of an inner surface of the female pin, and a conductive region, the conductive region forming a second portion of the inner surface of the female pin, the conductive region contacting the resistive region, the conductive region being located further than the resistive region from an open end of the female pin; and a male pin adapted to be inserted in the female pin along the inner surface of the female pin, the male pin being made of a conductive material. 
         [0012]    According to a second aspect of the present invention, an apparatus for hot swap of AC or DC line replaceable modules comprises: a pin system, the pin system being connectable to a replaceable module and connectable to a backplane, the pin system comprising a female pin connectable to the backplane, the female pin comprising a resistive region forming a first portion of an inner surface of the female pin, and a conductive region forming a second portion of the inner surface of the female pin, the conductive region contacting the resistive region, the conductive region being located further than the resistive region from an open end of the female pin, and a male pin adapted to be inserted in the female pin along the inner surface of the female pin, the male pin being made of a conductive material, and the male pin being connectable to the replaceable module, wherein resistance of the pin system decreases in a continuous manner as the male pin is inserted into the female pin along the resistive region and the conductive region of the female pin; and a hot swap detector connectable to the pin system, the hot swap detector detecting disconnection of the replaceable module from the backplane, and detecting connection of the replaceable module to the backplane. 
         [0013]    According to a third aspect of the present invention, a method for hot swap of AC or DC line replaceable modules comprises: providing a female pin for connection to a backplane, the female pin comprising a resistive region comprising a first hollow cylindrical shell forming a first portion of an inner surface of the female pin, and a conductive region comprising a second hollow cylindrical shell forming a second portion of the inner surface of the female pin, a start of a base of the conductive region contacting an end of a base of the resistive region, the conductive region being located further than the resistive region from an open end of the female pin; providing a male pin for connection to a line replaceable module, the male pin being adapted for insertion in the female pin along an inner hollow space of the female pin, the male pin being made of a conductive solid cylindrical material to fill the inner hollow space of the female pin; decreasing a resistance between the line replaceable module and the backplane in a continuous manner as the male pin is inserted into the female pin along the resistive region and the conductive region of the female pin; and increasing a resistance between the line replaceable module and the backplane in a continuous manner as the male pin is extracted from the female pin along the conductive region and the resistive region of the female pin. 
         [0014]    According to a fourth aspect of the present invention, a method for hot swap of AC or DC line replaceable modules comprises: providing a female pin for connection to a backplane; providing a male pin for connection to a line replaceable module, the male pin adapted to be inserted in the female pin; decreasing a resistance between the line replaceable module and the backplane in a continuous manner as the male pin is inserted into the female pin along a resistive region of the female pin and a conductive region of the female pin; and increasing a resistance between the line replaceable module and the backplane in a continuous manner as the male pin is extracted from the female pin along the conductive region and the resistive region of the female pin. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Further aspects and advantages of the present invention will become apparent upon reading the following detailed description in conjunction with the accompanying drawings, in which: 
           [0016]      FIG. 1  is a general functional block diagram of a subassembly electrical system containing line replaceable modules (LRMs) with hot-swap capability according to an embodiment of the present invention; 
           [0017]      FIG. 2  is a block diagram of an electrical configuration containing an integrated hot swap connector pins arrangement for hot swap of line replaceable modules according to an embodiment of the present invention; 
           [0018]      FIG. 3  illustrates an integrated hot swap connector pins arrangement for hot swap of line replaceable modules according to an embodiment of the present invention; 
           [0019]      FIG. 4  is a block diagram illustrating an exemplary implementation of a hot swap protection system using an integrated hot swap connector pins arrangement according to an embodiment of the present invention illustrated in  FIG. 3 ; 
           [0020]      FIG. 5  is a block diagram of an electrical configuration illustrating aspects of the operation of an integrated hot swap connector pins arrangement for detection of hot swap of line replaceable modules for DC input power according to an embodiment of the present invention illustrated in  FIG. 3 ; and 
           [0021]      FIG. 6  is a block diagram of an electrical configuration illustrating aspects of the operation of an integrated hot swap connector pins arrangement for detection of hot swap of line replaceable modules for AC input power according to an embodiment of the present invention illustrated in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Aspects of the invention are more specifically set forth in the accompanying description with reference to the appended figures.  FIG. 1  is a general functional block diagram of a subassembly electrical system containing line replaceable modules (LRMs) with hot-swap capability according to an embodiment of the present invention. The electrical system  100  illustrated in  FIG. 1  includes the following components: power systems  20 ; m line replaceable modules (LRMs)  40 _ 1 , . . . ,  40   —   m  of which only LRM  40   —   m  is shown; circuitry, control and load systems  50 ; m backplane connectors  104 _ 1 ,  104 _ 2 , . . . ,  104   —   m;  and a backplane protection system  191 . Operation of the electrical system  100  in  FIG. 1  will become apparent from the following discussion. 
         [0023]    LRM  40   —   m  includes a protection module  30   —   m;  a hot swap detector  134   —   m;  other circuitry  171   —   m;  a controls and arbitration logic unit  144   —   m;  and pin systems  183   —   m  and  173   —   m.  Backplane connector  104   —   m  includes pin systems that connect/disconnect from LRM  40   —   m  pin systems, when LRM  40   —   m  is inserted/extracted from backplane connector  104   —   m.  Backplane connectors  104 _ 1 ,  104 _ 2 ,  104 _ 3 , etc. also connect or disconnect from LRMs  40 _ 1 ,  40 _ 2 ,  40 _ 3 , etc. (not shown). Other circuitry  171   —   m  includes electronic and electric components of line replaceable module  40   —   m,  such as transistors, resistors, connectors, switches, etc. Hot swap detector  134   —   m,  protection module  30   —   m,  and pin system  183   —   m  perform hot swap protection functions during insertion or extraction of LRM  40   —   m.  Controls and arbitration logic unit  144   —   m  communicates with hot swap detector  134   —   m  and with other circuitry  171   —   m.    
         [0024]    Replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m  can be connected to and separated from backplane connectors  104 _ 1 ,  104 _ 2 , . . . ,  104   —   m,  which provide electrical power to replaceable modules. Some LRMs may connect to two backplane/motherboard connectors, one connector for power-pins and one for low voltage power supply input and discrete I/O lines for controls, signal sensing, etc. 
         [0025]    Power-in or power-out lines and other discrete signals may first be routed to the motherboard/backplane connectors. Then, when one LRM is attached to the corresponding mating backplane connector, proper power, control and power supply lines are connected from the backplane to the proper connector pins on the LRM, establishing the right connections (achieved by design) to get the desired functionality provided by that particular LRM. 
         [0026]    Backplane connectors  104 _ 1 ,  104 _ 2 , . . . , 104   —   m  connect to backplane protection system  191 . Backplane protection system  191  includes electric and electronic components such as switches, fuses, circuit breakers, resistors, etc., for protection of the backplane connectors. Input I/P power lines  123  lead into backplane protection system  191  and provide power from power systems  20 . Control I/O lines  125  transport control I/O data in and out from backplane protection system  191 , hence communicating control I/O data to replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m.  Output O/P power lines  127  leave backplane protection system  191  and connect to circuitry, control and load systems  50 . 
         [0027]    Protection module  30   —   m  protects replaceable module  40   —   m  and backplane connector  104   —   m  from in-rush currents during insertion of replaceable module  40   —   m  into the backplane connector  104   —   m  and electrical system  100 , and from transient voltages and current chopping during extraction of replaceable module  40   —   m  from backplane connector  104   —   m  and electrical system  100 . Protection module  30   —   m  and pin system  183   —   m  perform protection functions for replaceable module  40   —   m.  Inside replaceable module  40   —   m,  protection module  30   —   m  and pin system  183   —   m  protect other circuitry  171   —   m.  Protection module  30   —   m  and pin system  183   —   m  also protect the power systems  20 , the circuitry, control and load systems  50 , during hot swap of replaceable module  40   —   m.  Protection module  30   —   m  and pin system  183   —   m  protect components of electrical system  100  during hot swap insertion or removal of replaceable module  40   —   m  under normal or faulty modes of operation for high voltage DC and AC systems without the need to disconnect power. Protection modules  30   —   m  and pin system  183   —   m  permit safe and reliable insertion and removal of different types of LRMs during hot swap, without disturbing, damaging, or degrading up/down-stream adjacent LRMs and subsystems of electrical system  100 . Protection module  30   —   m  and pin system  183   —   m  also helps high voltage AC and DC load management LRMs to control the flow of electrical power to internal and external circuitry/loads and achieve proper protection of SSSDs or the wiring system. 
         [0028]    Electrical system  100  may be associated with an aircraft, a more electric aircraft, a ship, a laboratory facility, a piece of industrial equipment, etc. The power systems  20  provide electrical energy in electrical system  100 . The power systems  20  may include multiple power supply inputs, for redundancy. The power systems  20  may include AC and DC power supplies, electrical components such as transformers, inductances, resistances, etc. The power systems  20  may provide high DC or AC voltages or low DC or AC voltages to replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m.  Power systems  20  may provide and replaceable modules may use various AC voltages, such as, for example, 115V or 230V or higher, with fixed frequencies (such as, for example, 50/60 Hz or 400 Hz), or variable frequencies (such as, for example 360-800 Hz for aerospace applications), or DC voltages such as, for example, 28V or 270V. The power of replaceable module  40   —   m  may depend on the number of channels, as well as current rating and voltage of each channel. 
         [0029]    Replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m  receive electric power from power systems  20 . Replaceable modules  40 _ 1 , . . .  40   —   m  may be AC or DC Line Replaceable Modules (LRMs), cards, PC boards, etc. Replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m  may be high voltage AC and DC LRMs. Replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m  may have on-board Solid State Switching Devices (SSSDs). Replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m  may be high voltage Solid State AC and DC switches, referred to in the industry as Solid State Remote Power Controllers (SSPCs). Replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m  may be various types of LRMs such as: Power Supplies (PS-LRM), Digital Controllers (DC-LRM), AC Solid-State-Remote-Controller (AC-SSPC-LRM), DC Solid-State-Remote-Controller (DC-SSPC-LRM), LRMs used for aircraft platforms and More Electric platforms, PC boards or cards, etc. Solid State AC and DC switches can be used with a wide range of powers, from a few Watts to hundreds of KWatts. Replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m  including AC and DC Solid State Switching Devices (SSSDs) may manage high voltage AC and DC powers and loads, and may control the flow of electrical power to internal and external circuitry/loads, to achieve proper protection based on i 2 ·t (instantaneous overcurrent protection for large currents and proportionally time-delayed overload protection for smaller currents) to protect the SSSDs or the wiring system. 
         [0030]    Circuitry, control and load systems  50  receive electrical power through the replaceable modules, and use the electrical power downstream. Circuitry, control and load systems  50  may include various electrical systems, such as systems on an aircraft or ship, navigation systems, cabin systems, air conditioning systems, etc., systems in an industrial facility such as electrical equipment and tools, etc. Circuitry, control and load systems  50  may include power pins, DC and AC loads, electric circuits using DC and AC power that enable functioning of various services onboard a vehicle, or in a complex environment such as a laboratory facility. Services using AC and DC power may be an electric motor, an automatic braking system, a lighting system of a vehicle, a piece of industrial equipment, etc. 
         [0031]    Each LRM among LRMs  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m - 1  (not shown) includes a protection module like protection module  30   —   m  of LRM  40   —   m,  and a pin system like pin system  183   —   m.  Protection modules and pin systems ensure that hot swap of modules is properly done. Protection modules and pin systems avoid random pin arcing during mating process of a replaceable module to electrical system  100 . Protection modules and pin systems provide protection for safely inserting a board/module when the board is not electrically initialized, and for safely pulling a board-out while there is current passing through connectors. When electrical system  100  includes integrated systems, protection modules and pin systems provide hot swap protection beyond local boundaries of the replaceable modules. 
         [0032]    When boards/replaceable modules with multiple supply voltages are included in electrical system  100 , proper power sequencing for the modules is performed. Protection modules mitigate hot swap effects, so that various bus activities &amp; other operations taking place in electrical system  100  are not disturbed when hot swap of one or more replaceable modules is occurring. Together with control systems of electrical system  100 , protection modules and pin systems help establish autonomy of subsystems in electrical system  100  and automatic system reconfiguration based on the type of replaceable modules extracted or inserted. Information needed to describe the LRM type can be hard-wired through adjustable jumper connectors and/or backed-up by S/W into non-volatile memory locations readable to processor units during LRM initialization. 
         [0033]    Replaceable modules  40 _ 1 ,  40 _ 2 , . . . ,  40   —   m  and the associated protection modules may be designed to provide electrostatic discharge (ESD) protection during hot swap, because electrostatic discharges can disable ports by destroying interface ICs, replaceable modules connections, and surrounding electrostatic sensitive subsystems. 
         [0034]    Although the systems in electrical system  100  are shown as discrete units, it should be recognized that this illustration is for ease of explanation and that the associated functions of certain functional modules or systems can be performed by one or more physical elements. 
         [0035]      FIG. 2  is a block diagram of an electrical configuration  154  containing an integrated hot swap connector pins arrangement  180  for hot swap of line replaceable modules according to an embodiment of the present invention. The electrical configuration  154  illustrated in  FIG. 2  includes the following components: a backplane  104 ; a replaceable module  40 A; and a backplane protection system  191 . The electrical configuration  154  is included in electrical system  100 . Replaceable module  40 A may be a line replaceable module (LRM), and includes: a protection module  30 ; a hot swap detector  134 ; other circuitry  171 ; a controls and arbitration logic unit  144 ; and pin systems  183  and  173 . Backplane  104  includes pin systems  181  and  175 . Other circuitry  171  includes electronic and electric components of line replaceable module  40 A, such as transistors, resistors, connectors, switches, etc. Protection module  30 , pin system  183 , and pin system  181  form an integrated hot swap connector pins arrangement  180 . The integrated hot swap connector pins arrangement  180  integrates the protection module  30  into the structure of pin systems  181  and  183 . Hot swap detector  134  and integrated hot swap connector pins arrangement  180  perform hot swap protection functions. 
         [0036]    Replaceable module  40 A can be connected to and separated from backplane  104 , which provides electrical power to replaceable module  40 A. Replaceable module  40 A connects and separates through pin systems  183  and  173  from backplane  104 , at backplane pin systems  181  and  175 . Backplane  104  provides electrical power to controls and arbitration logic unit  144  when pin systems  173  and  175  mate. Backplane  104  provides electrical power to protection module  30  and hot swap detector  134  when pin systems  183  and  181  mate. 
         [0037]    Pin system  183  includes a number of pins, of which pins a, b, c, d, and e are shown. Pins of pin system  183  connect to protection module  30  and hot swap detector  134 . Pin system  173  includes power supply and controls pins, of which pins f, g, h, i, j, and k are shown. Pins of pin system  173  connect to controls and arbitration logic unit  144 . Controls and arbitration logic unit  144  also communicates with hot swap detector  134 . 
         [0038]    Backplane pin system  181  includes power pins of which pins l, m, n, o, and p are shown. Backplane pin system  181  connects to backplane protection system  191 . Backplane protection system  191  includes electric and electronic components such as switches, fuses, circuit breakers, resistors, etc., for protection of backplane  104 . Input I/P power lines  123  lead into backplane protection system  191 . Control I/O lines  125  transport control I/O data in and out from backplane protection system  191 , hence communicating control I/O data to replaceable module  40 A. Output O/P power lines  127  leave backplane protection system  191  and connect to loads. Backplane pin system  175  includes power supply input pins q and r, and control pins and discrete I/O pins of which pins s, t, u, and v are shown. Power supply input pins q and r connect to backplane protection system  191  through power supply inputs  185 . The control pins and discrete I/O pins of backplane pin system  175  also connect to backplane protection system  191 . 
         [0039]    The integrated hot swap connector pins arrangement  180  protects replaceable module  40 A and backplane  104  from in-rush currents during insertion of replaceable module  40 A into the backplane  104  and electrical system  100 , and from transient voltages and current chopping during extraction of replaceable module  40 A from backplane  104  and electrical system  100 . Integrated hot swap connector pins arrangement  180  also protects other circuitry  171  inside replaceable module  40 A. 
         [0040]    During insertion or extraction of replaceable module  40 A, electrical parameters associated with integrated hot swap connector pins arrangement  180  change. Hot swap detector  134  includes electronic circuitry (further described in  FIG. 3 ) that senses changes in electrical parameters associated with integrated hot swap connector pins arrangement  180 . Based on these changes, hot swap detector  134  detects whether a hot swap (insertion or extraction) of replaceable module  40 A is being performed or has been completed. Hot swap detector  134  also detects changes in electrical parameters associated with other circuitry  171 , changes which may occur during hot swap. 
         [0041]    Controls and arbitration logic unit  144  receives reports from hot swap detector  134  about completion of hot swap of replaceable module  40 A. When hot swap insertion of replaceable module  40 A is completed, controls and arbitration logic unit  144  starts normal control and communication functions inside replaceable module  40 A and at control pins and discrete I/O pins in pin systems  173  and  175 . 
         [0042]      FIG. 3  illustrates an integrated hot swap connector pins arrangement  180 A for hot swap of line replaceable modules according to an embodiment of the present invention. As illustrated in  FIG. 3 , integrated hot swap connector pins arrangement  180 A includes a male pin  415  and a female pin  418 . The male pin  415  is electrically connected to a board or replaceable module  425  along connection  402 . The board  425  may be, for example, a replaceable module  40 A as illustrated in  FIG. 2 . The length of the male pin  415  is L. The female pin  418  has two intervals, interval I and interval II. Interval I has length L 1 , and interval II has length L 2 . The total length of female pin  418  is equal to the length of the male pin  415 , L 1 +L 2 =L. The interval I of female pin  418  includes an external insulating region  404 , which covers an internal resistive cylindrical shell  405 . The interval II of female pin  418  is a conductive shell  406 . At the end of interval II, the conductive shell  406  connects to the end connection  407  for the female pin. The end connection  407  of the female pin typically connects to a motherboard/backplane. In the top view of female pin  418  in  FIG. 3 , the internal resistive cylindrical shell  405  inside the external insulating region  404  is illustrated. 
         [0043]    A graph for resistance variation of integrated hot swap connector pins arrangement  180 A along pin length is also shown at bottom in  FIG. 3 . When male pin  415  starts insertion into female pin  418  (makes gradual contact with interval I), the resistance of the integrated hot swap connector pins arrangement  180 A between points M (base of male pin  415 ) and R (tip of female pin  418 ) is Rmax. Rmax is set by the internal resistive cylindrical shell  405 . As the male pin  415  travels inside female pin  418  through interval I, the resistance of the integrated hot swap connector pins arrangement  180 A gradually decreases, as shown in the resistance graph between points P 1  and P 2 . The decrease of the resistance of pin arrangement  180 A as the male pin  415  travels inside female pin  418  may be a linear function of distance, but other dependences on distance may also be implemented with nonlinear resistive materials for the internal resistive cylindrical shell  405 . For example, the decrease of the resistance of pin arrangement  180 A as the male pin  415  travels inside female pin  418  may be a non-linear function of distance, when the resistance of the internal resistive cylindrical shell  405  varies nonlinearly with distance along interval I. 
         [0044]    When the male pin  415  has reached the end of interval I and makes contact with conductive shell  406  at the beginning of interval II, the resistance of the integrated hot swap connector pins arrangement  180 A becomes zero, as the conductive shell  406  shorts out all the resistance of the female pin. As the male pin  415  travels further through interval II of female pin  418 , the resistance of integrated hot swap connector pins arrangement  180 A remains zero, as the male pin  415  remains in contact with conductive shell  406  throughout full insertion into female pin  418 . Interval II conductive shell  406  ensures a good electrical connection for the male pin  415  to the female pin  418 . The length of intervals I and II can be chosen depending on application and desired resistance variation for integrated hot swap connector pins arrangement  180 A. The thicknesses of shells  404 ,  405 , and  406  can be chosen depending on application and on desired behavior for integrated hot swap connector pins arrangement  180 A. 
         [0045]    A mechanical spring, not shown in  FIG. 3 , may be connected to male pin  415  or to female pin  418 . The stiffness of the mechanical spring may be used to slow down the process of insertion and extraction of the male pin  415  from the female pin  418  through interval I of the female pin  418 . 
         [0046]    Variations to the hot swap connector pins arrangement  180 A are possible. Variations to the hot swap connector pins arrangement  180 A include, for example, integrating the resistive and insulating shells in a conductive shell for better mechanical and structural effectiveness of the hot swap connector pins arrangement. 
         [0047]    In  FIG. 3  only one integrated hot swap connector pins arrangement  180 A is shown for board  425 , but more integrated hot swap connector pins arrangements may be present. For example, a plurality of male pins like male pin  415  may be connected to board  425  along connection  402 . A plurality of female pins like female pin  418  may then be present to connect to the plurality of male pins. 
         [0048]      FIG. 4  is a block diagram illustrating an exemplary implementation of a hot swap protection system using an integrated hot swap connector pins arrangement  180 A according to an embodiment of the present invention illustrated in  FIG. 3 .  FIG. 4  shows how an integrated hot swap connector pins arrangement  180 A can be used to prevent random pin arcing during the mating process by reducing the DC current during the MAKE (insertion) or BREAK (extraction) process for a DC LRM. Similar methods and apparatus apply for hot swap of AC type LRMs. The integrated hot swap connector pins arrangement  180 A in  FIG. 4  reduces the number of pins for a hot swap protection system, and integrates a hot swap resistor into the pin arrangement. The function of a hot swap resistor is performed by the internal resistive cylindrical shell  405  as described in  FIG. 3 . 
         [0049]      FIG. 4  illustrates a DC Solid-State Remote Controller Line Replaceable Module (DC SSPC LRM)  40 A included in an electrical configuration  154 A. The DC SSPC LRM includes: high voltage Solid State DC switches, which are Solid State Power Controllers (SSPCs); a hot swap detector  134 ; a control and arbitration logic unit  144 ; an active or passive diode ORing system  232 ; a power connector  225 , and a second power strip  226 ; and a plurality of pin systems connected to the power connectors. A few SSPCs are shown as SSPC # 1  (element  41 A) and SSPC# 2  (element  41 B). More SSPCs may be present but are not shown in the picture. The SSPCs are connected to electrical rail  244  through fuses. For example, SSPC# 1   41 A is connected to electrical rail  244  through fuse  241 . 
         [0050]    In the circuit shown in  FIG. 4 , the control logic voltage is applied first when a DC SSPC LRM is inserted during hot swap. The power pins are applied after the control logic voltage is applied. For protection during hot swap insertion of the DC SSPC LRM, it is desirable that the in-rush current be reduced and the resistance between the DC SSPC LRM and the system in which the LRM is being inserted be gradually decreased. 
         [0051]    Power connector  225  connects to integrated hot swap connector pins arrangement  180 A. Integrated hot swap connector pins arrangement  180 A includes a male pin  415  and a female pin  418 . The male pin  415  can communicate with the backplane  104  through female pin  418 . Hot swap detector  134  connects to power connector  225  and bulk capacitors, and to male pin  415  of the integrated hot swap connector pins arrangement  180 A. Bulk capacitors are typically present on the DC LRM. SSPC# 1   41 A also connects to male pin  415  of the integrated hot swap connector pins arrangement  180 A. 
         [0052]    Initially, during insertion of the DC SSPC LRM  40 A into the host system, male pin  415  charges the bulk capacitors on the board. As male pin  415  is inserted into female pin  418 , the resistance of integrated hot swap connector pins arrangement  180 A gradually decreases, until male pin  415  gets shorted-out when it reaches the conductive shell of female pin  418 . The initial resistance of interval I of female pin  418  reduces in-rush current during insertion of DC SSPC LRM  40 A. When the male pin  415  is fully inserted into the female pin  418 , the resistance of pin arrangement  180 A becomes zero. Hot swap detector  134  detects the hot swap by detecting the voltage on the bulk capacitors, and informs the controls and arbitration logic unit  144 , when the hot swap is completed (i.e., board fully inserted). Hot swap detector  134  communicates with the controls and arbitration logic unit  144  through line  235 , and reports whether a hot swap is in progress or has been completed. After the hot swap is reported to be complete, controls and arbitration logic unit  144  communicates normally with SSPC# 1   41 A, through communication port  237  and discrete I/O signal and control port  238 , through the isolation section  236 . SSPC# 1   41 A also connects to the power connector  225  at male contact  218  L′ 1 , which connects to the backplane  104  at female contact  217  L 1 . The pair of pins  218  and  217  can also be an integrated hot swap connector pins arrangement as illustrated in  FIG. 3 , with pin  218  being a solid conductive pin, and pin  217  being a female pin comprising a resistive cylindrical shell and a conductive cylindrical shell as shown in  FIG. 3 . A second SSPC # 2   41 B may similarly connect to the controls and arbitration logic unit  144 , and to the backplane  104  at pin contacts L′ 2  and L 2 . An Nth SSPC #N may similarly connect to the controls and arbitration logic unit  144 , and to the backplane  104  at male pin contact  219  (L′ N ) and female contact  215  (L N ). The male and female pin pairs, such as L′ 2  and L 2 , . . . , L′ N  and L N  can be integrated hot swap connector pins arrangements as illustrated in  FIG. 3 , with male pins L′ 2 , . . . , L′ N  being solid conductive pins, and the female pins L 2 , . . . ,L N  comprising resistive cylindrical shells and conductive cylindrical shells as shown in  FIG. 3 . The male pin  415  and the female pin  418  of integrated hot swap connector pins arrangement  180 A provide power to DC SSPC LRM  40 A from backplane  104  through electrical rail  244 . The pin pairs L′ 1  and L′ 1 , L′ 2  and L 2 , . . . , L′ N  and L N  are used for routing power from the power bus from backplane  104  to various loads, through internal SSPC channels # 1 , # 2 , . . . , #N. Additional hot swap protection blocks may be present for backplane  104  connecting to female pins L 2 , . . . ,L N , or in DC SSPC LRM  40 A connecting to power connector  225 , as described in the co-pending non-provisional application titled “Method and Apparatus for Hot Swap of Line Replaceable Modules for AC and DC Electric Power Systems”, the entire contents of which are hereby incorporated by reference. 
         [0053]    In one embodiment, control power supply pins  228  and  229  may be part of a long/short pin assembly  251 , as described in co-pending non-provisional application titled “Method and Apparatus for Hot Swap of Line Replaceable Modules for AC and DC Electric Power Systems”, the entire contents of which are hereby incorporated by reference. In another embodiment, control power supply pins  228  and  229  may, together with female pins  252 , be part of an integrated hot swap connector pins arrangement  251  as described in  FIG. 3 . 
         [0054]    Reverse actions take place when a board is being pulled-out. For protection during hot swap extraction of a DC SSPC LRM, it is desirable that current chopping and transient voltages be avoided, with the resistance between the LRM and the system from which the LRM is extracted being gradually increased. Before physical break between the male pin  415  and the female pin  418 , the resistance of integrated hot swap connector pins arrangement  180 A gradually increases and goes to full resistance of interval I of female pin  418 . Hence, the interruption current through the pins is significantly reduced by the resistance of the internal resistive cylindrical shell  405  of female pin  418 . The interruption current is reduced to a negligible amount safe for extraction of DC SSPC LRM  40 A. The internal resistive cylindrical shell  405  of female pin  418  connects to SSPC# 1 , SSPC# 2 , etc., through line  244 . Hence, the integrated hot swap connector pins arrangement  180 A performs hot swap protection. 
         [0055]    The initial resistance Rmax of integrated hot swap connector pins arrangement  180 A reduces the in-rush current when an LRM is inserted into a backplane. When an LRM is extracted from a backplane, the resistance of the integrated hot swap connector pins arrangement  180 A gradually increases as male pin conductor  415  travels out of the female pin  418 , and interruption current due to LRM extraction is reduced to a safe amount for the LRM and other subsystems of electrical system  100 . 
         [0056]    The internal resistive cylindrical shell  405  of female pin  418  connects to hot swap detector  134  as well, and hot swap detector  134  detects when extraction of SSPC # 1  has been completed. The internal resistive cylindrical shell  405  of female pin  418  also contributes to detection of LRM insertion by hot swap detector  134 . The gradually varying resistance of integrated hot swap connector pins arrangement  180 A performs functions of protection module  30  illustrated in  FIG. 2 . 
         [0057]    Block  232  provides passive or active diode ORing of a redundant power supply input from multiple power sources for the control power supply of the LRM. Block  232  allows connection of multiple power supply voltage inputs to realize a fault tolerant power supply bus for the LRM. Block  232  includes an integrated active-diode-OR circuit which provides soft power-up/down capability, avoids excessive power losses and voltage drops, and controls voltage/current transients and in-rush OR current chopping during LRM insertion/extraction respectively. Additional details about the passive or active diode ORing block  232  can be found in co-pending non-provisional application titled “Method and Apparatus for Integrated Active-Diode-ORing and Soft Power Switching”, the entire contents of which are hereby incorporated by reference. Passive or active diode ORing block  232  connects to a 5V bus  233 , which also connects to SSPC# 1 , and to the other SSPCs present on the DC SSPC LRM. Passive or active diode ORing block  232  communicates with controls and arbitration logic unit  144  at a discrete I/O port. 
         [0058]    Unit  291  provides regulated DC-DC power conversion. In one exemplary implementation, unit  291  provides regulated DC-DC power conversion from 5V-to-5V, or from 5V-to-3.5V, etc. Unit  291  may also provide isolation if required. 
         [0059]    The motherboard/backplane includes sections  227  and  224 , which include mating connectors. The mating connectors  217 ,  216 ,  215 , and  418  in section  224  are part of the motherboard/backplane and are fixed. DC SSPC LRM)  40 A can be inserted or extracted from the motherboard/backplane. 
         [0060]    As shown in  FIG. 4 , the integrated hot swap connector pins arrangement  180 A is used for detection and proper mitigation of hot swap during insertion or extraction of LRM/boards. This arrangement eliminates in-rush currents during the initial insertion of a board/module with all bulk/bypass capacitors at zero volts. 
         [0061]    The integrated hot swap connector pins arrangement  180 A illustrated in  FIGS. 3 and 4  also prevents current chopping when a board/LRM is pulled-out while there is a load current, in a normal or fault situation. Hence, the protection circuit shown in  FIG. 4  prevents current chopping and also eliminates large transient voltages due to inductive current variations Ldi/dt. Pulling a board out without the hot swap protection while there is inductive current passing through connector pins may cause current chopping which results in arcing and excessive voltage/current transients. Inductive current may be due to on-board inductive filters or inductive loads, for example. Arcing and excessive voltage/current transients can have severe safety consequences due to risk of voltage shock to personnel or to other subsystems during failure modes or faulty conditions, such as short circuit conditions. 
         [0062]    The speed of insertion/extraction of DC SSPC LRM  40 A from backplane  104  may be manually controlled, or may be controlled by springs attached to the male or female pins of the integrated hot swap connector pins arrangements in  FIG. 4 . If the speed of insertion/extraction of DC SSPC LRM  40 A from backplane  104  is not controlled, for example, if insertion/extraction of DC SSPC LRM  40 A from backplane  104  is performed too fast, additional hot swap protection blocks can be included for backplane  104  connecting to female pins L 2 , . . . ,L N , or in DC SSPC LRM  40 A connecting to power connector  225 , as described in the co-pending non-provisional application titled “Method and Apparatus for Hot Swap of Line Replaceable Modules for AC and DC Electric Power Systems”, the entire contents of which are hereby incorporated by reference. Such additional hot swap protection blocks can perform hot swap protection for LRMs, backplane connectors, etc. 
         [0063]    In  FIG. 4 , multiple integrated hot swap connector pins arrangements may be present to achieve a more uniform hot swap in a discrete fashion. A plurality of male pins like male pin  415  attached to DC SSPC LRM  40 A can communicate with one or more female pins like female pin  418 . The plurality of integrated hot swap connector pins arrangements may exhibit various pin lengths and various Rmax resistances of internal resistive cylindrical shells of the female pins, to obtain additional levels of protection during hot swap. 
         [0064]      FIG. 5  is a block diagram of an electrical configuration  500  illustrating aspects of the operation of an integrated hot swap connector pins arrangement  180 A for detection of hot swap of line replaceable modules for DC input power according to an embodiment of the present invention illustrated in  FIG. 3 . Block  180 A_E in  FIG. 5  is a conceptual circuit using a variable resistor for illustrating aspects of the operation of an integrated hot swap connector pins arrangement  180 A. The equivalent circuit  180 A_E for integrated hot swap connector pins arrangement  180 A includes an equivalent switch S 1   508  and an equivalent variable resistor  510  with maximum resistance Rmax. The variable resistor  510  models the resistance variation of integrated hot swap connector pins arrangement  180 A with pin motion. 
         [0065]    When insertion of male pin  415  into female pin  418  is commenced, joined connectors  504  and  506  are connected. A DC power source  502  powers the circuit in  FIG. 5 . The following discussion references the description of the integrated hot swap connector pins arrangement  180 A from  FIG. 3 . The resistance of variable resistor  510  is dependent on the position of the male pin  415  inside female pin  418 , as described at  FIG. 3 . 
         [0066]    During an initial step, the male pin  415  starts insertion into female pin  418  on a distance x, where x&lt;&lt;L 1 , where L 1  is the length of interval I of female pin  418 . During this initial step, the resistance of integrated hot swap connector pins arrangement  180 A is R≈Rmax. Hence, in the equivalent circuit  180 A_E for integrated hot swap connector pins arrangement  180 A, equivalent switch S 1  is open. 
         [0067]    During an intermediate insertion step, the male pin  415  is further inserted into female pin  418  on a distance x, where 0&lt;x&lt;L 1 , where L 1  is the length of interval I of female pin  418 . During this intermediate step, the resistance R of integrated hot swap connector pins arrangement  180 A varies from Rmax to 0, Rmax&gt;R&gt;0, with resistance R of integrated hot swap connector pins arrangement  180 A gradually decreasing as the male pin  415  is being inserted into female pin  418 . 
         [0068]    During a final insertion step, the male pin  415  is further inserted into ) female pin  418  on a distance x, where x&gt;L 1 , where L 1  is the length of interval I of female pin  418 . During this final insertion step, the resistance R of integrated hot swap connector pins arrangement  180 A is zero, as conductive region  406  ensures a solid and efficient electrical connection between the male pin  415  and the female pin  418 , as illustrated in  FIG. 3 . Hence, in the equivalent circuit  180 A_E for integrated hot swap connector pins arrangement  180 A, equivalent switch S 1  is closed. 
         [0069]    A capacitor  525  connected at the Power-out line passes lower frequencies and stops high frequencies. A voltage divider  512  is connected to the Power-out line and to the equivalent resistor  510 . The voltage divider  512  may output a voltage proportional to equivalent resistor  510 . The signal from voltage divider  512  passes through an isolation unit  514 , and is then amplified by an amplifier  516 . 
         [0070]    The block diagram of electrical configuration  500  in  FIG. 5  illustrates how hot swap detection status is achieved for a DC input power, using integrated hot swap connector pins arrangement  180 A. The output of amplifier  516  contains information about hot swap status. For example at the beginning of insertion of male pin  415  in female pin  418 , the voltage from equivalent resistor  510  is large, because equivalent switch S 1  is open. Hence, the output signal of amplifier  516  at point P 8  is high, if the amplifier  516  is non-inverting, for example. On the other hand, at the completion of insertion of male pin  415  in female pin  418 , the voltage from equivalent resistor  510  is zero, because equivalent switch S 1  is closed and equivalent resistor  510  is bypassed. Hence, the output signal of amplifier  516  at point P 8  is low, if the amplifier  516  is non-inverting. 
         [0071]    In the diagram in  FIG. 5 , if resistor  510  were not a variable resistor, but a fixed resistor with resistance Rmax, then the resistance between points K 1  and K 2  would change abruptly between 2 values (0 and Rmax), approximating the effect of a long/short pin system with an external resistor. 
         [0072]      FIG. 6  is a block diagram of an electrical configuration  600  illustrating aspects of the operation of an integrated hot swap connector pins arrangement  180 A for detection of hot swap of line replaceable modules for AC input power according to an embodiment of the present invention illustrated in  FIG. 3 . Block  180 A_F in  FIG. 6  is a conceptual circuit using a variable resistor for illustrating aspects of the operation of an integrated hot swap connector pins arrangement  180 A. The equivalent circuit  180 A_F for integrated hot swap connector pins arrangement  180 A includes an equivalent switch S 2   608  and an equivalent variable resistor  610  R 2  with maximum resistance Rmax. The variable resistor  610  R 2  models the resistance variation of integrated hot swap connector pins arrangement  180 A with pin motion. 
         [0073]    When insertion of male pin  415  into female pin  418  is commenced, joined connectors  604  and  606  are connected. An AC power source  602  powers the circuit in  FIG. 6 . The following discussion references the description of the integrated hot swap connector pins arrangement  180 A from  FIG. 3 . The resistance of variable resistor  610  is dependent on the position of the male pin  415  inside female pin  418 , as described at  FIG. 3 . 
         [0074]    During an initial step, the male pin  415  is inserted into female pin  418  on a distance x, where x&lt;&lt;L 1 , where L 1  is the length of interval I of female pin  418 . During this initial step, the resistance of integrated hot swap connector pins arrangement  180 A is R≈Rmax. Hence, in the equivalent circuit  180 A_F for integrated hot swap connector pins arrangement  180 A, equivalent switch S 2  is open. 
         [0075]    During an intermediate insertion step, the male pin  415  is further inserted into female pin  418  on a distance x, where 0&lt;x&lt;L 1 , where L 1  is the length of interval I of female pin  418 . During this intermediate step, the resistance R of integrated hot swap connector pins arrangement  180 A varies from Rmax to 0, Rmax&gt;R&gt;0, with resistance R of integrated hot swap connector pins arrangement  180 A gradually decreasing as the male pin  415  is being inserted into female pin  418 . 
         [0076]    During a final insertion step, the male pin  415  is further inserted into female pin  418  on a distance x, where x&gt;L 1 , where L 1  is the length of interval I of female pin  418 . During this final insertion step, the resistance R of integrated hot swap connector pins arrangement  180 A is zero, as conductive region  406  ensures a solid and efficient electrical connection between the male pin  415  and the female pin  418 , as illustrated in  FIG. 3 . Hence, in the equivalent circuit  180 A_F for integrated hot swap connector pins arrangement  180 A, equivalent switch S 2  is closed. 
         [0077]    A capacitor  625  connected at the Power-out line passes lower frequencies and stops high frequencies. A voltage divider  612  is connected to the Power-out line and to the equivalent resistor  610 . The voltage divider  612  may output a voltage proportional to equivalent resistor  610 . The signal from voltage divider  612  passes through an isolation unit  614  and a rectification unit  630 , and is then amplified by an amplifier  616 . 
         [0078]    The block diagram of electrical configuration  600  in  FIG. 6  illustrates how hot swap detection status is achieved for an AC input power, using integrated hot swap connector pins arrangement  180 A. The output of amplifier  616  contains information about hot swap status. For example at the beginning of insertion of male pin  415  in female pin  418 , the voltage from equivalent resistor  610  is large, because equivalent switch S 2  is open. Hence, the output signal of amplifier  616  at point P 18  is high, if the amplifier  616  is non-inverting, for example. On the other hand, at the completion of insertion of male pin  415  in female pin  418 , the voltage from equivalent resistor  610  is zero, because equivalent switch S 2  is closed and equivalent resistor  610  is bypassed. Hence, the output signal of amplifier  616  at point P 18  is low, if the amplifier  616  is non-inverting. 
         [0079]    In the diagram in  FIG. 6 , if resistor  610  R 2  were not a variable resistor, but a fixed resistor with resistance Rmax, then the resistance between points K 3  and K 4  would change abruptly between 2 values (0 and Rmax), approximating the effect of a long/short pin system with an external resistor. 
         [0080]    Although the integrated hot swap connector pins arrangements discussed in  FIGS. 1 ,  2 ,  3 ,  4 ,  5 , and  6  were discussed in the context of AC and DC SSPC LRMs, the hot swap protection systems in  FIGS. 1 ,  2 ,  3 ,  4 ,  5 , and  6  are equally applicable to hot swap protection of other types of modules, circuits, and systems. 
         [0081]    While an exemplary geometry for integrated hot swap connector pins arrangement  180  was presented in  FIG. 3 , other geometries and mechanical implementations are possible for integrated hot swap connector pins arrangement  180 , to achieve the gradual variation of resistance during pin insertion and extraction described in the current application. 
         [0082]    The integrated hot swap connector pins arrangements discussed in the current application integrate multiple long/short pin arrangements and multiple resistors into one pin, to achieve soft-start/stop for insertion and extraction of replaceable modules. The integrated hot swap connector pins arrangements discussed in the current application perform hot swap protection functions that would otherwise require multiple long/short pin arrangements with different pin lengths for the short pins, and multiple resistors connected to the long/short pin arrangements. Hence, the integrated hot swap connector pins arrangement  180 A may be a one-step system or a multiple step system. A one-step integrated hot swap connector system integrates a long/short pin arrangement and a resistor into one integrated hot swap connector pins arrangement, to achieve soft-start/stop for insertion and extraction of replaceable modules. A multiple-step integrated hot swap connector system integrates multiple long/short pin arrangements and multiple resistors into one integrated hot swap connector pins arrangement, to achieve soft-start/stop for insertion and extraction of replaceable modules. 
         [0083]    The timing of boards/LRMs insertion/extraction process can be controlled by the stiffness of a mechanical spring system, which may be incorporated into an integrated hot swap connector pins arrangement  180 A and used to oppose the direction of pin motion. A preferred mode of operation for integrated hot swap connector pins arrangement  180 A is to achieve soft-start through a uniformly varying resistive channel for which the resistance is gradually reduced during pin insertion, from a large resistance value (pin not inserted) to a zero resistance value (pin fully inserted). During board/LRM extraction, the resistance variation is reversed. Hence during board/LRM insertion in-rush currents are eliminated, and during board/LRM extraction current chopping is reduced. 
         [0084]    The integrated hot swap connector pins arrangements discussed in the current invention can be used for hot swap of both low voltage and high voltage modules. Additional details regarding use of integrated hot swap connector pins arrangements for hot swap can be found in co-pending non-provisional application titled “Method and Apparatus for Hot Swap of Line Replaceable Modules for AC and DC Electric Power Systems”, the entire contents of which are hereby incorporated by reference. 
         [0085]    The integrated hot swap connector pins arrangements discussed in the current application effectively protect up/down stream subsystems and eliminate electrical current/voltage transients which would otherwise require complete shut-down of the larger electrical system before any hot swap can be achieved. 
         [0086]    The hot swap methods and apparatuses using the integrated hot swap connector pins arrangements discussed in the current application can be implemented at three levels: at the level of basic hot swap, at the level of full hot swap, and at the level of highly available hot swap. 
         [0087]    During basic hot swap, console intervention signals the electrical system  100  that a card/replaceable module is about to be removed or inserted. If the module is being taken out, the OS can gracefully terminate running software, and then signal the card/module to disconnect itself and power down. The reverse happens when a card/module is inserted in electrical system  100 . The card/module may also be enumerated and mapped by electrical system  100 . 
         [0088]    During full hot swap, the method by which the operating system of electrical system  100  is told of the impending insertion or extraction of a board/module is predefined. A micro-switch attached to the card injector/ejector, or to an integrated hot swap connector pins arrangement  180 , can give an early-warning signal to the system that an operator is about to remove a card. Software and hardware disconnect processes follow the switch activation. The enumeration interrupt can also inform the operating system of the electrical system  100  of the impending event. After the OS has terminated the board&#39;s functions, the interrupt signals to the operator that the board/module can be removed. On the other hand, when a new board is installed, the OS can automatically configure the system software of electrical system  100 . This signaling method allows the operator to install or remove boards/modules without reconfiguring the system at the console. 
         [0089]    During highly available hot swap, a hot swap controller with capacity to reconfigure software in a running system in electrical system  100  is used. Software and hardware components can be reconfigured automatically under application control. Console commands or ejector-switch activation and board/module removal usually unload the driver or install a new driver. By allowing software to control the board&#39;s state, both performance and system complexity of electrical system  100  are increased. Control lines to the CPU of electrical system  100  can inform the operating system (OS) that a board/module is present. The OS can then apply power to the board/module. Next, the hardware connection layer indicates that the board is powered up. The master system controller then signals to release the board/module from reset and connects it to the bus. Individual boards/modules can be identified and shut down, and others can be brought up in their place. 
         [0090]    The integrated hot swap connector pins arrangement  180  and the apparatuses presented in  FIGS. 1 ,  2 ,  3 ,  4 ,  5 , and  6  achieve soft-switching, soft-start/soft-power-up and soft-stop/soft-power-down to eliminate arcing, random pin arcing, etc., and AC or DC current and v/i transients during the MAKE or BREAK process; eliminate in-rush currents during initial insertion of a board/module with all bulk/bypass capacitors at zero volts; mitigate bus contentions; prevent current chopping when a board is pulled-out when there is a load current (in a normal or fault situation); achieve controlled di/dt or dv/dt transients, for transient currents i(t)=C(dv/dt) and transient voltages v(t)=L(di/dt); eliminate large transient voltages due to v(t)=L(di/dt) and current chopping causing excessive voltage/current transients resulting in severe safety consequences during failure modes; can incorporate circuit breaker functions for additional safety considerations; provide fault tolerance for safety considerations; can be implemented with sequencing control; can be implemented with diagnostics and health monitoring/reporting; mitigate fault challenges including ESD protection; can be integrated into electrical system  100  with a high level of integration in hardware, software and in the operating system; and properly detect the process of a board/LRM insertion or extraction so that S/W is gracefully shut-down to prevent abnormal operation and/or physical damage to sensitive interface circuitry. This type of “prior-to-event” detection prevents disturbance to various discrete signal/control data lines or communication bus activities. Also, proper power sequencing is presented for boards/LRMs with multiple logic power supply voltages and low and high DC voltages and AC sources of power. For proper operation of control circuitry, logic power is connected first and disconnected last. 
         [0091]    Although some aspects of the present invention have been described in the context of aerospace applications, it should be realized that the principles of the present invention are applicable to other environments.