Patent Publication Number: US-3876909-A

Title: High speed switch

Description:
United States Patent 1 Halbach et al.  
 [ Apr. 8,1975  
 1 1 HIGH SPEED SWITCH [75] Inventors: Edward A. l lalbach, Milwaukee;  
 Paul M. Gailatin, Brookfield, both of Wis.  
 [73] Assignee: Allis-Chalmers Corporation,  
 Milwaukee, Wis.  
  22 Filed: Oct. 1, 1973 211 Appl. No.: 402,607  
 Primary Examiner-G. Harris Attorney, Agent. or FirmRobert C. Sullivan [57] ABSTRACT A high speed switch for short-circuiting the electrical output of an alternating current generator or other generator. The shorting switch includes a stationary shorting bar connected to one electrical output line to be shorted. The other output lines to be shorted are respectively connected each to a separate hairpinshaped contact carrier of spring material and having low mass and low bounce characteristics. Each contact carrier is normally engaged by a contact hold-down means to hold the respective contact carrier and its associated contact out of conductive engagement with the shorting bar. The contact holddown means is normally held in its contact hold-down (nonshorting) position by a magnetic detent device. Upon the occurrence of a fault in the electrical output system being protected, a signal is transmitted to the magnetic detent device to reduce the magnetic holding force sufficiently to permit the stored energy of the spring-like contact carriers, aided by an auxiliary spring, to rapidly move the contact hold-down means out of hold-down relation to the spring-like contact carriers, the contact carriers with their respective associated contacts moving into conductive engagement with the shorting bar. Shorting of the output lines instantaneously removes the energy source supplying fault current. In essence, the fault current is diverted from the fault to the shorting device. A motor driven relatching device is provided to move the armature which supports the contact hold-down means into magnetically latched engagement with the magnetic detent means.  
 27 Claims, 6 Drawing Figures SHEET 1 [IF 3 r 32 26 P IALTERNATOR SHORTING DEVICE I4 L. fi\ $fi:l-36  
  28 34 40 DIESEL ACTO DC ENGINE ALTERNATOR RECTIFIER f I I0 2&#39;0( 2 I2 22 4 Q 55A 1 TO TRIP COIL ON MAGNETIC DETENT DEVICE DETECTION AMPLIFIER men SPEED SWITCH BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a high speed switch such as a shorting switch for use in shorting an electrical output such as the output of an alternating current generator or other generator, and to a contact carrier means for such switch, which shorting switch is particularly useful in an emergency situation where a fault has occurred on the system to which the electrical output is connected. The switch of the invention is particularly useful although not restricted to use in the electrical system of a diesel-electric locomotive as a shorting switch to stop a flash-over on direct current traction motors which are supplied with rectified direct current power from an alternator or alternating current generator, the shorting switch being used to short the output of the alternating current generator upon the occurrence of a flash-over on the direct current traction motors.  
 2. Description of the Prior Art In diesel-electric locomotives an alternating current generator supplies electrical power through rectifiers to the direct current traction motors which drive the wheels of the locomotive. A common and troublesome problem in such systems is that particularly under certain operating conditions of the system a flash-over will occur on the commutator of the direct current motor or motors which will cause the direct current input to the direct current traction motor or motors to increase at a rate of increase of the order of magnitude of one million to two million amperes per second. Such a short circuit current on the DC. traction motors if allowed to continue would ruin the traction motors.  
  It is broadly known to provide a device for short circuiting the output of an alternating current generator or other generator, whereby to extinguish an electrical fault in the output circuit of the generator, as described, for example, in the bulletin entitled CC6 Court-Circuiteur Ultra-Rapide Hexapolaire which describes a high speed short circuiting device manufactured by Etablissements Merlin Gerin, Grenoble, France.  
 STATEMENT OF THE INVENTION It is an object of the invention to provide a high speed switch device which substantially eliminates contact bounce and maintains the contacts in a firm contactmaking position after they have been released from a spring-loaded open position.  
  It is another object of the invention to provide an improved support for carrying and supporting the contacts of a high speed switch which substantially eliminates contact bounce and insures that the contacts remain in closed position without contact bounce.  
  It is another object of the present invention to&#39;provide an improved high speed short circuiting device adapted to short circuit an electrical output, as from an alternating current generator, for example, upon the detection of an electrical fault in the output system of the generator, whereby to cause fault current to discon tinue flow through the fault point in the output system.-  
  It is still a further object of the invention to provide an improved contact carrier or support for a high speed switch which is adapted to carry an extremely high electrical current of the order of thousands of amperes for a very short period of time.  
  It is another object of the invention to provide an improved current carrying carrier or support for a movable contact, which support is self-energized to move the contact carried thereby into contact-making position with a fixed contact, with the contact carrier or support being adapted to carry an extremely high electrical current for a very short duration, permitting the contact carrier or support to have minimal mass with consequent minimal momentum and minimal contact bounce on contact closure.  
  It is another object of the invention to provide a high speed switch having a movable contact and contact support which have a low mass with consequent low momentum, hence minimal bounce on closure of the contact, yet having high contact loading when the contact is closed.  
  In achievement of these objectives, there is provided in accordance with an embodiment of the invention a high speed switch such as a shorting switch for shortcircuiting an electrical output such as the output of an alternating current generator or other generator, whereby to cut off power to a fault, such as a flashover, in the electrical system to which the electrical output is connected. The shorting switch includes a sta tionary shorting bar connected to one of the electrical output lines to be shorted. The other output lines to be shorted are respectively connected each to a separate hairpin-shaped or U-shaped contact carrier of spring material, the respective contact carriers having low mass and low bounce characteristics. Each contact carrier is normally engaged by a contact hold-down means to hold the respective contact carrier and its associated contact out of conductive engagement with the shorting bar. The contact hold-down means is normally held in its contact hold-down position, (corrresponding to nonshorting position of the shorting bar and shorting contacts) by a magnetic detent device. However, upon the occurrence of a fault in the electrical output system being protected, such as a flash-over on DC. traction motors connected in the electrical output system, a signal is transmitted to the magnetic detent device to reduce the magnetic holding force sufficiently to permit the stored energy of the spring-like hairpin-shaped contact carriers, aided by an auxiliary spring, to rapidly move the contact hold-down means out of hold-down relation to the spring-like contact carriers, the contact carriers with their respective associated contacts moving due to the stored spring energy of the contact carriers into conductive engagement with the shorting bar, thereby shorting the respective electrical output lines connected to the stationary shorting bar and to the movable shorting contacts. Shorting of the output lines instantaneously removes the energy source supplying fault current. However, the alternator short circuit current through the shorting bar, shorting contacts and associated Contact carriers will decay at a prescribed rate dependent upon the alternator characteristics. In essence, the fault current is diverted from the fault to a shorting device. A motor driven relatching device is provided to mechanically move the movable armature which supports the contact hold-down means into magnetically latched engagement with the magnetic detent means, thereby returning the contact carriers and shorting contacts carried thereby to nonshorting position.  
  Further objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a typical installation in which the shorting device in accordance with an embodiment of the invention might be installed; namely, showing the shorting device installed in the electrical power system of a diesel-electric locomotive;  
  FIG. 2 is a view in elevation, and partially in section, of the shorting device in magnetically latched position in which the shorting device is not in its shorting position;  
  FIG. 3 is a view similar to FIG. 2 but showing the shorting device in shorting position;  
  FIG. 4 is a view taken substantially along line IV-IV of FIG. 2 showing details of the hairpin spring contact carriers or supports for the shorting contacts, and the associated stationary shorting bars;  
  FIG. 5 is a view in vertical section taken along line V--V of FIG. 2, of the magnetic detent device; and  
  FIG. 6 is a side elevation view of the motor operated relatching mechanism.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is shown schematically a typicalsystem in which the high speed shorting device of the invention may be used, namely, the electrical system of a diesel-electric locomotive. A diesel engine indicated at 10 rotatably drives an alternating current generator or alternator generally indicated at 12. The alternator 12 has six output leads representing the six phase output of the alternator, these leads being indicated respectively at 14, l6, 18, 20, 22 and 24. Alternatively, the leads 14, 16, 18, 20, 22, 24 may represent the output leads of a three phase alternator having two windings per phase, in which case leads 14 and would correspond to phase 1, leads l6 and 22 would correspond to phase 2, and leads 18 and..24 would correspond to phase 3.  
  The alternator output leads l4, 16, 18, 20, 22 and 24 are connected to an AC-DC rectifier means generally indicated at 38 and the output terminals 40 of the rectifier means 38 are connected by means of conductors 55A, 55B to the direct current traction motors 42, four of the motors 42 being shown. The traction motors 42 drive the wheels of the locomotive. When driving four traction motors as shown, alternator l2 typically may have an output of 3000 horsepower.  
  As seen in the schematic diagram of FIG. 1, the high speed shorting device comprises a stationary conductor bar or shorting bar 26 which is conductively connected to the output lead 14 of alternator 12 and a pair of shorting contacts 28 and 30 which are mounted for movement toward stationary conductor bar 26 and which are respectively connected to output leads l6 and 18 of alternator 12.  
  The high speed shorting device also includes a second stationary conducting bar or shorting bar 32 which is conductively connected&#39;to alternator output lead 20. A movable shorting contact 34 adapted to be moved into engagement with stationary conductor or shorting bar 32 is conductively connected to alternator output lead 22, and a shorting contact 36 which is also adapted to be moved into contact with stationary conductor or shorting bar 32 is conductively connected to alternator output lead 24. As will be explained &#39;in more detail hereinafter, when a flash-over occurs on the DC. traction motors, the contacts 28 and 30 are adapted to be moved into electrically conductive engagement with stationary bar 26 thereby shorting alternator output leads 14, .16 and 18 together; and, simultaneously therewith, the contacts 34 and 36 are adapted to be moved into electrically conductive engagement with stationary condutor bar 32 thereby shorting alternator output leads 20, 22 and 24 together.  
  As best seen in the views of FIGS. 2, 3 and 5, the short-circuiting device includes a magnetic holding or detent subassembly generally indicated at 49 and comprising a casing 50 of nonmagnetic material such as aluminum in which are positioned a pair of spaced flat square-shaped permanent magnet plates 52A and 52B between which is interposed a flat pole plate 54 of suitable magnetic material such as soft iron. The permanent magnet plates 52A and 52B may be Indox ceramic magnets, formed of barium iron oxide. Pole plates 56 and 58 of a suitable magnetic material such as soft iron are positioned contiguous and in contact with the outwardly facing surfaces of the respective permanent magnet plates 52A and 528. The centrally located pole plate 54 is of approximately twice the thickness of the respective pole plates 56 and 58.  
  The permanent magnet 52A and 52B are permanently magnetized in a direction parallel to the thickness dimension of the plates 52A and 52B, as indicated by the arrows M in FIG. 5. The magnetic flux flows from the permanent magnet plates 52A and 52B into and upwardly, relative to FIG. 5, through center pole piece 54 and into the magnetic armature 64 in its magnetically latched position. The magnetic flux then passes from armature 64 downwardly, relative to FIG 5, into the respective magnetic pole pieces 56 and 58 and thence returns to the permanent magnet plates 52A and 523 to complete the magnetic circuit.  
  The pole plates 54, 56, 58 are vertically higher (relative to FIG. 5) than the permanent magnet plates 52A and 52B, and a trip coil 60 is wound around the upper end relative to the view of FIG. 5 of the central pole piece 54. Trip coil 60 is normally de-energized, but is momentarily energized when detection device 51 (FIG. 1) detects a predetermined rapid rate of rise of DC. current (indicative of a fault current) in one of the direct current lines supplying the DC. traction motors 42.  
  The construction and design of the magnetic structure is such that the demagnetization of the permanent magnets 52A, 52B does not take place under the demagnetizing influence of the trip coil 60. The magnetic flux through armature 64 is diverted by action of trip coil 60 and follows a leakage path between the edges of the three plates 54, 56 and 58, without demagnetizing the permanent magnets 52A and 52B. This arrangement results in simplicity of construction. The design of the magnetic detent device 49 utilizing an aluminum casting 50 as previously described is satisfactory where external magnetic influences are not a problem. However, where external magnetic fields present a problem the detent device 49 can be most effectively magnetically isolated by use of a casting 50 made of soft iron. The permanent magnet plates 52A and 52B, pole plates 54, 56, 58 (except for the upper end surfaces of the pole plates) and trip coil 60 are all encapsulated in a suitable insulating material such as an epoxy resin.  
 Conductor leads (not shown) connected to the ends of the trip coil 60 pass through an aperture in casing 50 of the magnetic detent 49 and are connected to the terminals of detection amplifier 44 which amplifies the signal from device Sl&#39;indicative of a fast-rate of rise of the DC. current input to DC. traction motors 42.  
  Detection device 51 (FIG. 1) may comprise a toroidal-shaped magnetic core 53 having a central aperture through which the DC. current conductor 55A passes. A coil 57 is wound on magnetic core 53, the output leads of coil 57 being connected to a detection amplifier 44 which in turn energizes trip coil 60 on magnetic detent device 49. Conductor 55A is inductively related to magnetic core 53 and to coil 57 in such manner that a predetermined rapid rate of rise of DC. current in conductor 55A, which might be caused by a fault current in the traction system, typically by a flash-over on one of the traction motors 42, will induce a sufficient voltage in coil 57 (which is transmitted to trip coil 60 through detection amplifier 44) to cause unlatching of the magnetic detent device 49, whereby to permit release of the shorting contacts 28, 30, 34, 36 into shorting engagement with stationary conductor bars 26, 32, as will be explained in more detail later.  
  Instead of sensing and utilizing the rapid rate of rise of current in the DC output to actuate trip coil 60 as just described, the trip coil 60 may instead be actuated upon the sensing of a predetermined current amplitude in the DC. output by a device or means which senses amplitude of current in the DC. output.  
  The shorting bars 26, 32, the shorting contacts 28, 30, 34, 36 and the contact carriers 92A, 92B, 92C, 92D (to be described) are all mounted within a housing generally indicated at 59 having a detachable cover 61. The housing 59 must be of a suitable electrically insulating material such as a suitable molded plastic to act as insulating support means for the various shorting bars and shorting contact carrier members. The cover 61 may be of steel.  
  Means generally indicated at 63 which will be described in more detail hereinafter is mounted on cover 61 for relatching the shorting contacts in nonshorting position after a fault current has been suppressed.  
  An armature 64 of suitable magnetic material such as soft iron is normally engaged with the upper end of the magnetic pole pieces 54, 56, 58 of the magnetic holding device 49, previously described. A stem member 66 of a material having suitable strength such as steel is carries by armature 64 and extends vertically upwardly (relative to FIGS. 2 and 3) through a guide bushing 67 in stationary support structure 59. As best seen in the views of FIGS. 2 and 4, a contact hold-down means generally indicated at 68 formed of electrically insulating material is provided. Contact hold-down means 68 is provided with a central passage 70 therethrough which receives stem 66 of armature 64, whereby contact hold-down means 68 is slidably mounted on armature stem 66. Contact hold-down means 68 comprises an elongated narrow body 72 including body portions 72A and 72B lying on opposite sides of the central passage 70 of the device 68. The outer ends of body portions 72A and 72B are received in guide slots 79 in housing or stationary support structure 59 to guide hold-down means 68 in its vertical movement relative the views in FIGS. 2 and 3. A pair of lug-like portions 74 project laterally outwardly from theopposite surfaces of each of the respectivebody portions 72A and 728 for a total of four lug-like portions each indicated at 74. As will be explained in more detail, the four lug-like portions serve to hold the shorting contacts 28, 30, 34 and. 36 in open nonshorting position when armature 64 is held in magnetically latched condition by magnetic detent device 49 (FIG. 2).  
  The upper portion of stem 66 is threaded as indicated at 76 and a nut 78 is located at an adjusted position on the threaded portion 76 to define the upper limiting position of contact hold-down means&#39;68. A washer 77 isv positioned betweeen the lower end of nut 78 and the upper end of contact hold-down means 68 (relative to the views of FIGS. -2 and 3). The central portion of contact hold-down means 68 bounding the axial passage bears against the under surface of washer 77, which in turn bears against nut 78 to limit upward movement of contact hold-down means 68. An auxiliary coil spring 80 is positioned beneath and in engagement with contact hold-down means 68. The lower end of coil spring 80 bears against a spring seat 82 which is coaxially positioned about stem 66 and rests on the upper surface of guide bushing 67. The upper end of spring 80 bears against the lower portion of contact hold-down means 68.  
  In addition to the magnetic holding or detent device 49, the detent means in the illustrated embodiment also comprises the armature 64, the stem 66 of the armature, and the contact hold-down means 68.  
  The stationary rigid shorting bars 26 and 32 shown schematically in FIG. 1 are physically positioned within insulating housing 59 in a substantially common horizontal plane with each other and on opposite sides of contact hold-down means 68, as seen in FIGS. 2 and 3. The longitudinal dimension of the respective shorting bars 26 and 32 extends parallel to the longitudinal dimension of contact hold-down means 68. The respective stationary shorting bars 26 and 32 are respectively conductively connected by the respective rigid conductor members 27 and 33 to terminals on housing 59 which, in turn, are respectively conductively connected to the alternator output leads 14 and 20 (FIG. 1). Contacts A, 90B are carried in spaced relation to each other by the under surface of stationary shorting bar 26; and contacts 90C, 90D are carried in spaced relation to each other by the under surface of stationary shorting bar 32.  
  In accordance with an important feature of the invention, the shorting contacts 28 and 30 which are respectively engageable with contacts 90A, 90B carried by the under surface of shorting bar.26 are each respectively fixed to and supported by the upper surface of the upper leg of a hairpin-shaped or U-shaped contact carrier 92A, 92B of a spring or spring-like material such as beryllium copper; and in a similar manner, contacts 90C and 90D carried by the under surface relative to the view of FIGS. 2, 3 and 4 of shorting bar 32 are adapted to be engaged by contacts 34 and 36 fixed to and carried by the upper surface of the upper leg of the respective hairpin or U-shaped contact support members or carriers 92Cv and 92D, respectively. The  
 vbutton-like contacts such as 28, 30, 34, 36 and 90A,  
  Each button-like contact 28, 30, 36, 90A, etc. is formed of a refractory contact material known for antiweld properties. Such contact materials are well-known in the art and are commercially available. Each buttonlike contact 90A, 90B, 90C, 90D is fixedly secured to the under surface (relative to the views in the drawings) of its corresponding conductor shorting bar 26, 32. The mating surfaces of both contacts of each pair of cooperating contacts such as 90A-28, 90C-34, etc., are each in the shape of a partial cylinder (i.e., less than 360 arc), the two partial cylinders of each pair of contacts lying on axes which are at right angles to each other. This arrangement of crossed cylindrical contacts at each pair of mating contact surfaces assures single point contact closure between each pair of mating contacts.  
  As best seen in the view of FIG. 2, the contact carrier 92C which supports contact 34 is formed of a springlike material such as beryllium copper and is fixedly secured at one of its ends by screw 94 to the horizontal portion of a rigid terminal conductor 96C, to which output lead 22 of alternator 12 is connected. In a similar manner, contact carrier 92A which supports contact 28 is secured to rigid terminal conductor 96A; contact carrier 92B and its contact 30, to rigid terminal conductor 96B; contact carrier 92D and its contact 36, to rigid terminal conductor 96D. The respective conductors l6, 18, 24 are in turn connected to the rigid terminal conductors 96A, 96B, 96D.  
  The hairpin-shaped or U-shaped contact carriers 92A, 92B, 92C and 92D each respectively having minimal mass in a self-contained, self-energized contact system, the minimal mass substantially preventing rebound or bouncing of the shorting contacts 28, 30, 34, 36 after-these shorting contacts have been moved into conductive relation to stationary shorting bars 26 and 32by&#39;tripping of magnetic detent device 49, as&#39;will be explained in more detail hereinafter.  
  As best seen in FIG. 2, when the armature member 64 is in magnetically held engagement with the upper end of the magnetic detent or holding device 49, the contact hold-down means 68 which is carried by the armature shaft or stem 66 is in engagement with the free ends of the four spring-like contact carriers 92A, 92B, 92C and 92D and is forcing the free ends of the respective contact carriers toward the fixed ends thereof against the natural tendency of the free ends of the contact carriers to move away from the fixed ends thereof, thereby storing energy in the respective contact carriers 92A-92D, inclusive. In the FIG. 2 position just described, the contacts 28 and 30 carried by the respective contact carriers 92A and 92B do not engage the stationary contacts 90A and 90B carried by the stationary shorting bar 26 and the contacts 34 and 36 carried by the respective contact carriers 92C and 92D do not engage the corresponding fixed contacts 90C and 90D carried by the stationary shorting bar 32.  
  Also, in the magnetically latched position of FIG. 2, the auxiliary coil spring 80 is compressed and has energy stored therein which, when released to the position of FIG. 3, will move spring 80 to the expanded position shown in FIG. 3 in which it will hold armature 64 and contact hold-down means 68 at a position in which any possible rebounding of members 64 and 68 in the shorted position of FIG. 3 will be out of range of the shorting contacts 28, 30, 34, 36. Thus, due to the action of auxiliary spring 80, possible rebounding of armature 64 and of contact hold-down means 68 when these members are in the shorted position of FIG. 3 will be ineffective to cause reopening of the shorting contacts 28, 30, 34 and 36.  
  Auxiliary spring also supplements the spring force provided by contact carriers 92A, 92B etc. to aid in raising armature 64 and contact hold-down means 68 from the latched position shown in FIG. 2 to the position shown in FIG. 3 in which armature 64 engages stop member 73.  
  Typically, when the contacts 28, 30, 34, and 36 are in the nonshorted latched position of FIG. 2, each contact carrier 92A, 92B, 92C and 92D pushes upwardly on the magnetically held armature subassembly (i.e., armature 64, armature stem 66 and contact holddown device 68) with a force of approximately 50 pounds, for a typical total upward force exerted by the four contact carriers 92A, etc. in the illustrated example of approximately 200 pounds. In addition, in the nonshorted, latched position of FIG. 2, the auxiliary spring 80 typically may push upwardly on the armature subassembly with a force of approximately 50 pounds. Thus, in the example just given, the four contact carriers 92A, etcl, and the auxiliary spring 80 exert a cumulative upward force of approximately 250 pounds on the armature subassembly. This force is counteracted in the&#39;magnetically latched position of FIG. 2 by the magnetic pull exerted on the armature subassembly by the magnetic detent device 49, which magnetic pull typically might be approximately 500 pounds before the demagnetizing trip pulse is applied to detent device 49.  
  As best seen in the view of FIG. 3, when a trip pulse of the proper polarity and magnitude from the detection amplifier 44 is received by the trip coil 60 of the magnetic detent device generally indicated at 49, the magnetic force holding armature 64 is sufficiently reduced by the trip pulse on coil 60 to permit the stored energy in the hairpin-shaped contact carriers 92A-92D, inclusive, aided by auxiliary spring 80, to force the armature assembly upwardly with a very rapid motion, moving contact hold-down means 68 and its lugs 74 vertically upwardly in the same motion, permitting the contacts 28, 30, 34 and 36 carried by the respective spring contact carriers 92A-92D, inclusive, to be moved very rapidly by the stored spring energy of contact carriers 92A etc. into shorting engagement with the respective contacts A, 90B, 90C and 90D carried by the stationary shorting bars 26 and 32. Typically, when the contacts 28, 30, 34 and 36 are in the shorted position of FIG. 3 each contact carrier 92A, 92B, 92C and 92D forces its associated contact into engagement with the cooperating contact carried by the stationary shorting bar 26 or 32 with a force of approximately 40 pounds due to the stored energy still remining in the contact carriers 92A, etc., thereby providing high contact loading, even after some of the stored energy in the contact carriers 92A, 92B, etc., has been expended in moving the contacts 28, 30, 34, 36 to the shorted position of FIG. 3. In the shorted position of FIG. 3, the movable free leg of each respective hairpinshaped contact carrier 92A, etc., still has not expanded to its natural unstressed position and in fact is still far from its unstressed position.  
  It will be understood that the various values of forces exerted by the contact carriers 92A, etc., by the auxiliary spring 80, and by magnetic detent device 49 are given only by way of example.  
  Typically, armature 64 is releasedfrom magnetic engagement with magnetic detent device 49 approximately 0.002 second after detection device 51 transmits a signal pulse to trip coil 60 of the detent device 49, and the shorting contacts have finished moving to the shorting position of FIG. 3 approximately 0.003 second after armature 64 is released.  
  It should be emphasized that it is the stored spring energy in the U-shaped contact carriers 92A, 92B, etc. which moves the shorting contacts 28, 30, 34, 36 into the shorted position of FIG. 3.  
  After the shorting contacts 28, 30, 34, and 36 carried by contact carriers 92A, etc., have moved into shorting engagement with the fixed contacts carried by shorting bars 26, 32, armature 64 continues to move upwardly under the influence of auxiliary spring 80, as well as under the influence of its kinetic energy until the upper surface 65 of armature 64 engages the under surface 73 of a stop member in the form of an elastomeric or rubber pad or the like 71 mounted on the stationary support structure 59 in the path of movement of armature 64. Member 71 serves as an upper limit for the movement of armature 64, the elastomeric character of member 71 also serving to absorb the kinetic energy of the upwardly moving armature 64.  
  It can be seen that the vertical travel of armature 64 from its magnetically latched position in engagement with magnetic detent 49 (FIG. 2) to its unlatched position in abutting relation to under surface 73 of stop member 71 (FIG. 3) is greater than the travel of the shorting contacts 28, 30, 34 and 36 from open (or nonshorting) position (FIG. 2) to closed (or shorting) position (FIG. 3). Hence, in they shorting position (FIG. 3)  
 the contact hold-down means 68 is at a vertical height such that the under surfaces of the respective lug-like elements 74 of the contact hold-down means 68 are positioned above and out of contact with the free ends of the spring-like contact carriers 92A, 92B, 92C and 92D. When the apparatus is in the shorted position of FIG. 3, the auxiliary spring 80maintains the contact hold-down means 68 in the position just described in which lug elements 74 of contact hold-down means 68 do not engage the contact carriers&#39;92A, 92B, 92C and 92D, so that any rebound movement of the contact hold-down means 68 and/or armature 64 in the FIG. 3 position will be out of range of shorting contacts 28, 30, 34 and 36, thereby insuring against any reopening of the shorting contacts due to possible rebounding of the hold-down means 68 and/or armature 64.  
  The direct current field of alternator 12 is opened by appropriate means (not shown) substantially simultaneously with the movement of the shorting device to shorting position when a fault current is sensed by sensing device 51. This is done to expedite decay of the shorted current.  
  Upon the application of the short circuit to the output leads of alternator 12 as just described, and particularly with the field of the alternator being opened substantially simultaneously with the application of the short circuit, the voltage output of the alternator drops to substantially zero in a very short time due to the well-known inherent characteristics of alternators under short circuit conditions, with the result that the total watt-seconds of energy consumed in the shorting device during short circuit is small enough to allow the use of low mass shorting members. This is of significance particularly in connection with the movable contact carrriers 92A, etc., and the respective contacts 28, etc., carried by the contact carriers, since the low mass of these members minimizes contact closing momentum and hence minimizes contact bounce.  
  The time required for the output voltage of the alternator 12 to drop to substantially zero, with consequent substantially zero short circuit current through the shorting contacts and contact carriers varies depending upon the short circuit characteristics of the particular alternator 12. However, the duration of short circuit current flow through the shorting contacts and contact carriers will always be of very short duration.  
  The short duration of the short circuit current through the contacts 28, 30, 34 and 36 and the associated spring-like current carrying contact carriers 92A, 92B, 92C and 92D permits the contact carriers 92A-92D, inclusive, and their associated contacts to be of low mass as compared to the mass which would be required for current carrying members carrying an equal amount of current for a longer period of time. Typically, the short circuit current carried by the respective shorting contacts 28, 30, 34 and 36 and the associated contact carriers 92A-92D, inclusive, may have an instantaneous value of approximately 16,000 amperes. As previously mentioned, the low mass of the contact carriers 92A-92D, inclusive, minimizes contact bounce when the shorting contacts move into the shorting position of FIG. 3.  
  Shorting the alternator output conductors removes the energy source for the fault current, whether it be flash-over in a traction motor or a fault in other electrical components. Fault current drops to zero almost instantly while alternator shorting current in the shorting device may continue for a fraction of a second or for a few seconds dependent upon alternator characteristics.  
  After the alternator 12 has been shorted by the movement of the shorting contacts into the position shown in FIG. 3, and the alternator voltage has dropped to substantially zero after a short time lapse depending on alternator characteristics under open field conditions, the shorting contacts may then be returned to the nonshorting position of FIG. 2 by means of the relatching mechanism generally indicated at 63 in FIGS. 2, 3 and 6.  
  As seen in FIGS. 2 and 3, the upper end of the armature stem 66 projects through a passage in the cover 61, the upper end surface of the stem 66 projecting a distance above the upper surface of cover 61 by an amount in FIG. 3 greater than that in FIG. 2 equal to the travel of the armature stem 66 from its latched position of FIG. 2 to its unlatched position in FIG. 3. The relatching mechanism 63, as best seen in FIGS. 6, 3 and 6. comprises a pair of generally rectangular-shaped leaf springs and 102, respectively. The leaf springs 100 and 102 are loosely mounted on an upstanding stud or bolt member 104 which is secured to the cover 61. The inner ends of the leaf springs 100 and 102 (i.e., the lefthand ends relative to FIG. 6) overlie the upper end of the armature stem 66 which projects through the cover 61. The lower leaf spring 100 is bent or has a set about a bend line 106, whereby the right-hand portion of spring 100 (relative to FIG. 6) is bent downwardly about bend line 106; and the upper leaf spring 102 has its inner or left-hand portion thereof bent upwardly relative to the view of FIG. 6 about a bend line 108. The two bend lines 106 and 108 lie in substantially vertical alignment with each other.  
  A coil spring 110 has the lower end thereof received in a recess in the upper surface of cover 61 with the upper end of spring 110 bearing against the under surface of the lower leaf spring 100 whereby to normally bias both the leaf springs 100 and 102 in an upward direction relative to the view of FIG. 6 to a position in which springs 100 and 102 are normally out of contact with armature stem 66 in both the FIG. 2 and FIG. 3 positions of armature 64.  
  A vertical abutment 107 prevents lateral displacement of springs 100 and 102, and a horizontal abutment 109 limits the vertical upward movement of springs 100 and 102.  
  The relatching mechanism 63 also includes a motorreduction gear assembly generally indicated at 112 having an output shaft 114 to which is secured a cam member 116, whereby cam member 116 rotates with shaft 114. Cam member 116 has secured to the laterally inner surface thereof (relative to FIGS. 2 and 3), and eccentrically located relative to the axis of the drive shaft 114, a roller member 118 which is free to revolve independently about its own support axis.  
  Assume that the upper end of the armature stem 66 is in the elevated position shown in FIG. 3 corresponding to the shorted position of the shorting contacts and that it is desired to relatch the armature 64 in the magnetically latched position shown in the nonshorted position of FIG. 2. A reset pushbutton is actuated to energize the motor-gear drive 112 to initiate rotation of cam member 116 from the neutral position in which it is shown in FIG. 6, through an angle of rotation sufficient to carry the roller member 118 through and beyond a position in which it engages the upper end of the spring 102 to force the springs 102 and 100 in a downward direction relative to the view of FIG. 6, thereby causing the under surface of the lower spring 100 to engage the upper end of the armature stem 66 to push the armature stem 66 andthe connected armature 64 in a downward direction relative to the views in the drawings for a distance such that armature 64 engages the upper end of the pole pieces 54, 56 and 58 and is magnetically held thereto, as seen in FIG. 2.  
  The downward movement of stem 66 in the relatching operation carries the contact hold-down device 68 downwardly until the stem 66, armature 64, hold-down device 68, and shorting contacts 28, 30, 34, 36 all assume the magnetically latched position shown in FIG. 2.  
  Cam 1 16 cooperates with a switch 120 to de-energize the reset motor at the proper angular rotation so the roller 118 will not interfere with subsequent motion of the armature-stem assembly 64-66 druing the shorting operation.  
  The use of the interposed springs 100, 102 to transmit the motion of relatching roller 118 to the upper end of armature stem 66 provides a safety factor which prevents breakage of the parts which might occur in the case of overtravel of roller 118 if there were a direct contact between the roller 118 and stem 66.  
  A suitable signal means (not shown) is provided to advise the locomotive operator or the like that the shorting device has been actuated and shorted the alternator 12. The operator may then, after waiting for at most a few seconds to in sure that the current through the shorting contacts has decayed to substantially zero, depress the reset pushbutton to initiate cam rotation for a reset cycle in which the shorting contacts are again magnetically latched in nonshorting position (FIG. 2) as previously described.  
  From the foregoing detailed description of the invention, it has been shown how the objects of the invention have been obtained in a preferred manner. However, modifications and equivalents of the disclosed concepts such as readily occur to those skilled in the art are intended to be included within the scope of this invention.  
  The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
  1. A high speed switch for short circuiting at least two electrical output lines of an alternating current electrical generator upon the occurrence of a predetermined condition, comprising a first electrical conductor member adapted to be conductively connected to one of said electrical output lines, a second electrical conductor member of spring material, said second conductor member being adapted to be conductively connected to the other of said electrical output lines, detent means for normally holding said second conductor member against the spring force of said second conductor member out of conductive relation with said first conductor member, said detent means being adapted to release said second conductor member upon the occurrence of said predetermined condition, said second conductor member upon release by said detent means moving due to its own spring energy into conductive relation with said first conductor member, whereby to short circuit said electrical output lines to each other, the short circuit current through said second conductor member decaying from X amperes to substantially zero amperes in a short time interval determined by the short circuit characteristics of the alternating current electrical generator upon opening ofits field circuit whereby said second conductor member may have a mass which is substantially less than the mass which would be required for said second conductor member for a continuous current rating of X amperes.  
  2. A high speed switch as defined in claim 1 in which said first conductor member is a rigid bar-like member having an electrical contact element thereon, said second conductor member being a contact carrier and having an electrical contact carried thereby which is movable into engagement with said electrical contact carried by said first conductor member when said second conductor member is released by said detent means.  
  3. A high speed switch as defined in claim 1 in which said second conductor member is a spring of substantially hairpin (i.e., U-) shape, one leg of said hairpinshaped conductor member being anchored in fixed position, the other leg of said hairpin-shaped conductor member being normally engaged by said detent means to store spring energy in said hairpin-shaped conductor member, said other leg being movable toward and into conductive relation with said first conductor member when said other leg is released by said detent means.  
  4. A high speed switch as defined in claim 1 in which said detent means comprises magnetic means, an armature magnetically engageable with said magnetic means, means carried by said armature for normally holding said second conductor member against the spring force of said second conductor member out of conductive relation with saidfirst conductor member, and trip coil means associated with said magnetic means and effective upon the occurrence of said predetermined condition to permit release of said armature from said magnetic means whereby to permit movement of said second conductor member under its own spring force into conductive relation with said first conductor member. m  
  5. A high speed switch as defined in claim 1 in which the short circuit current carried by said conductor member has a maximum value of the order of magnitude of thousands of amperes, and said short circuit current decays to substantially zero ina short time interval as determined by the short circuit characteristics of said-alternating current generator upon opening of its field circuit, whereby the mass of said second conductor member may be made substantially less than the mass of a conductor member having a continuous or steady state current rating of said maximum value.  
  6. A high speed switch as definedin claim 1 including means for relatching said detent means subsequent to the release of said second conductor member, whereby said detent means again holds said second conductor member against the spring force of said second conductor member out of conductive relation with said first conductor member.  
  7. A high speed switch as defined in claim 4 including relatching means adapted to move said armature into magnetic engagement with said magnetic means whereby to again hold said second conductor member against the spring force of said second conductor member out of conductiverelation with said first conductor member.  
  8. A high speed switch as defined in claim 1 compris ing a hold-down means forming part of said detent means for normally, engaging said second conductor member to hold said second conductor member against the spring force of said second conductor member out of conductive relation with said first conductor member, and an auxiliaryspring engaging said hold-down means, said auxiliary spring being effective to maintain said hold-down means at a position in which any bouncing movement of said hold-down means subsequentto movement of said second conductor-member into conductive relation to said first conductor member will be out of range of said second conductor member, whereby any bouncing movement of said hold-down means will be ineffective to move said second conductor member out of conductive relation with said first conductormember. Y  
  9. A high speed switch. as defined in claim 4 comprising an auxiliary spring engageable with said means carried by said armature, said auxiliary spring being effective to maintain said-meanscarried by said armature at a position in which any bouncing movement of said means carried by said armature after said second conductor member has been actuated into conductive relation with said first-conductor member will be out of range of said second conductor member, whereby any bouncing movement of said means carried by said armature will be ineffectiveto movesaidsecond conductor memberout of conductive relation with said first conductor member. e  
  10. A high speed switch, comprising a;;first electrical conductor member -a second electrical}, conductor memberof spring material, detent means for normally holding said second conductor member against the spring force of said second conductor member. out of conductive relation with saidfirst conductor member, said detent means being adapted to release said second conductor member upon actuation of said detent means to a release condition, said second conductor member upon release by said detent means moving due to its own spring energy into conductive relation with said first conductor member.  
  11. A high speed switch as defined in claim 10 in which said secondconductor member is a spring of substantially U-shape,one leg of saidhairpin (i.e. U-) shape conductor membeer being anchored in fixed position, the other leg of said U-shaped conductor member being normally engaged by said detent means to store spring energy in said U-shaped conductor member, said other leg being movable toward and into conductive relation with said first conductor member when said other leg is released by said detent means.  
  12. A high speed switch as defined in claim 10 in which said second conductor member when in conductive relation to said first conductor member is adapted to carry a current which decays from a maximum value of X amperes to substantially zero amperes in a short time interval whereby said second &#39;conductor member may have a mass which is substantially less than the mass which would be required for said second conductor member for a continuous current rating of X amperes.  
  13. A high speed switch as defined in claim 10 in which the current carried by said second conductor member has a maximum value of the order of magnitude of thousands of amperes, and said current decays to substantially zero in a time interval of the approximate order of magnitude of a few seconds or less whereby the mass of said second conductor member may be made substantially less than the mass of a conductor member having a continuous or steady state current rating of said maximum value.  
  14. A high speed switch as defined in claim 10 in which said first,conductor member is a rigid bar-like membei&#39; having an electrical contact element thereon, said second conductor member being a contact carrier and having an electrical contact carried thereby which is movable into engagement with said electrical contact carried by said first conductor member when said second conductor member is released by said detent means. i H  
  15. A high speed switch as definedin claim 10 includ; ing means for relatching said detent means subsequent to the release of saidsecond conductor member, whereby said detent means again holds said second conductormember against the, spring force of said second conductor member outof conductive relation with said first conductor member.  
  16. A high speed switch as defined in claim 10 in which said detent means comprises magnetic means, an  
 armature magnetically engageable with said magnetic means, means carried by said armature for normally holding said second conductor member against the spring force. of said second conductor member out of conductive relation with said first conductor member, and trip coil means associated with said magnetic means and effective upon the actuation of said trip coil means to release condition to permit release of said armature from said magnetic means whereby to permit movement of said secondconductor member under its own spring force into conductive relation with said first conductor member.  
  17. A high speed switch as defined in claim 16 including relatching means adapted to move said armature into magnetic engagement with said magnetic means whereby to again hold said second conductor member against the spring force of said second conductor member out of conductive relation with said first conductor member.  
  18. A high speed switch as defined in claim 10 comprising a hold-down means operatively associated with said detent means for normally engaging said second conductor member to hold said second conductor member against the&#39;spring force of said second conductor member out of conductive relation with said first conductor member, and an auxiliary spring engaging said hold-down means, said auxiliary spring being effective to maintain said hold-down means at a position in which any bouncing movement of said hold-down means subsequentto movement of said second conductor member into conductive relation to said first conductor member will be out of range of said second conductor member, whereby any bouncing movement of said hold-down means will be ineffective to move said second conductor member out of conductive relation with said first conductor member.  
  19. A high speed switch as defined in claim 16 comprising an auxiliary spring engageable with said means carried by said armature, said auxiliary spring being effective to maintain said means carried by said armature at a position in which any bouncing movement of said means carried by said armature after said second conductor member has been actuated into conductive relation with said first conductor member will be out of range of said second conductor member, whereby any bouncing movement of said means carried by said armature will be ineffective to move said second conductor member out of conductive relation with said first conductor member.  
  20. A high speed switch for short-circuiting in excess of two electrical lines to each other, comprising a first electrical conductor member adapted to be conductively connected to one of said electrical lines, said first conductor member being a rigid bar-like member, a plurality of additional electrical conductor members each respectively adapted to be conductively connected to the respective other electrical lines, each conductor member of said plurality of additional conductor members being of spring material, a detent means common to all of said additional conductor members for normally holding the plurality of additional conductor members against the spring force of the respective additional conductive members out of conductive relation with said first conductor member, said detent means being adapted to simultaneously release said plurality of additional conductor members upon actuation of said detent means to release condition, said plurality of additional conductor members upon release by said detent means moving due to the spring energy of the respective additional conductor members into conductive relation with said first con ductor member.  
  21. A high speed switch as defined in claim &#39;20 in which each of said plurality of additional conductor members is a spring of substantially hairpin (i.e., U-) shape, one leg of each said hairpin-shaped conductor member being anchored in fixed position, the other leg of each said hairpin-shaped conductor member being normally engaged by said detent means to store spring energy in said hairpin-shaped conductor member, said other leg of each said additional conductor member being movable toward and into conductive relation with said first conductor member when said other leg is released by said detent means.  
  22. A high speed switch as defined in claim 20 comprising a hold-down means forming part of said detent means for normally engaging said plurality of additional conductor members to hold said plurality of additional conductor members against the spring force of said additional conductor members out of conductive relation with said first conductor member, and an auxiliary spring engaging said hold-down means, said auxiliary spring being effective to maintain said hold-down means at a position in which any bouncing movement of said hold-down means subsequent to movement of said plurality of additional conductor members into conductive relation to said first conductor member will be out of range of said plurality of additional conductor members, whereby any bouncing movement of said hold-down means will be ineffective to move any of said plurality of additional conductor members out of conductive relation with said first conductor member.  
  23. A high speed switch as defined in claim 20 in which said detent means comprises magnetic means, an armature magnetically engageable with said magnetic means, means carried by said armature for normally holding said plurality of additional conductor members against the spring force of said additional conductor members out of conductive relation with said first conductor member, and trip coil means associated with said magnetic means and effective upon the actuation of said trip coil means to release condition to permit release of said armature from said magnetic means whereby to permit movement of said plurality of additional conductor members under their own spring force into conductive relation with said first conductor member.  
  24. A high speed switch for electrically connecting a plurality of electrical conductor members to each other, comprising a rigid member of electrically conducting material, a plurality of electrical conductor members each made of spring material, a detent means common to said plurality of electrical conductor members for normally holding said plurality of electrical conductor members against the spring force of the respective conductor members out of conductive relation with said rigid member, said detent means being adapted to simultaneously release said plurality of electrical conductor members upon actuation of said detent means to release condition, said plurality of conductor members upon release by said detent means moving due to the spring energy of the respective conductor members into conductive relation with said rigid member.  
  25. A high speed switch as defined in claim 24 in which each of said plurality of conductor members is a spring of substantially hairpin (i.e., U-) shape, one leg of each said hairpin-shaped conductor member being anchored in fixed position, the other leg of each said hairpin-shaped conductor member being normally engaged by said detent means to store spring energy in said hairpin-shaped conductor member, said other leg of each said plurality of conductor members being movable toward and into conductive relation with said rigid member when said other leg is released by said detent means.  
  26. A high speed switch as defined in claim 24 comprising a hold-down means forming part of said detent means for normally engaging said plurality of conductor members to hold said plurality of conductor members against the spring force of said plurality of conductor members out of conductive relation with said rigid member, and an auxiliary spring engaging said holddown means, said auxiliary spring being effective to maintain said hold-down means at a position in which any bouncing movement of said hold down means subsequent to movement of said plurality of conductor members into conductive relation to said rigid member will be out of range of said plurality of conductor members, whereby any bouncing movement of said holddown means will be ineffective to move any of said plurality of conductor members out of conductive relation with said rigid member.  
  27. A high speed switch as defined in claim 24 in which said detent means comprises a magnetic hold- &#39;down means, an armature magnetically engageable with said magnetic hold-down means, means carried by said armature for normally holding said plurality of conductor members against the spring force of said plurality of conductor members out of conductive relation with said rigid member, and trip coil means associated with said magnetic hold-down means and effective upon the actuation of said trip coil means to a release condition to permit release of said armature from said magnetic hold-down means whereby to,permit movement of said plurality of conductor members under their own spring force into conductive relation with said rigid member.  
 (5/69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Patent No. 3,876,909 Dated April 8,1975  
 Inventor-( Edward A. Halbach and Paul M. Gallatin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
 The cover sheet should be corrected to read as follows: [75] Inventors: Edward A. Halbach, Milwaukee;  
 Paul M. Gallatin, Brookfield, both of Wis.  
 Column 13, line 11, after &#34;said&#34; second should be inserted. Column 14, line 13, &#34;membeer&#34; should be member ignrd and fiealcd this eleventh Day of May 1976 [SEAL] Arrest:  
 RUTH C. MASON AINSNHX Officer C. MARSHALL DANN (mnmisxl&#39;unvr 01&#39; Parents and Trademarks mg UNlTED STATES PATENT OFFICE QERHFICATE 0F CURRECHON Patent NO. I I D t d Inventor(s) Edward A. Halbach and Paul M. Gallatin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
 The cover sheet should be corrected to read as follows:  
 [75] Inventors: Edward A. Halbach, Milwaukee;  
 Paul M. Gallatin, Brookfield, both of Wis.  
 Q Column 13, line 11, after &#34;said&#34; second should be inserted. Column 14, line 13, &#34;membeer&#34; should be member fiagntd and ficalrd this 0 eleventh Day of May 1976 [SEAL] Arrest.  
 RUTH C. MASON C. MARSHALL DANN Alluring Officer (&#39;unzmissimu&#39;r (IfItJIUIIIS and Trademarks