Automatic transfer switch utilizing back-to-back mounted molded case circuit breakers or molded case switches to connect a load to a normal power source and a standby power source

Abstract

An automatic transfer switch (ATS) utilizing molded case circuit breakers (MCCB) or molded case switches (MCS) to connect and disconnect an electrical load to a Normal power source and a Standby power source. The ATS comprising two MCCB or MCS mounted back-to-back one connected to a Normal power source and the other to a Standby power source. Bus bars electrically connect the poles on the load side of the MCCB or MCS connecting the ATS to a load. A rotating cam drive mechanism drives Toggle Levers with attached stored energy opening springs toggles to open and close the MCCB or MCS through the leverage of fulcrum points. A ratchet mounted on the output shaft of a unidirectional gear motor rotates the cam drive mechanism. An interlock bar prevents both MCCB from closing at the same time.

Claims

1. An automatic transfer switch (ATS) utilizing molded case circuit breakers (MCCB) or molded case switches (MCS) to connect and disconnect an electrical load to a Normal power source and a Standby power source, said ATS comprising: two molded case circuit breakers (MCCB) or molded case switches (MCS) mounted back-to-back to connect a load to a Normal power source and a Standby power source; bus bars electrically connecting the poles on the load side of the MCCB or MCS connecting the ATS to a load; a rotating cam drive mechanism driving toggle levers with attached stored energy opening springs to toggle open and closed the MCCB or MCS through the leverage of fulcrum points; a ratchet mounted on the output shaft of a unidirectional gear motor to rotate the cam drive mechanism and declutch from the motor shaft when the cam drive mechanism is manually operated; a fixed length non-conducting interlock bar located between movable elements of each MCS or MCCB to prohibit the opposite switch from closing at the same time; and a safety lock that blocks operation of the cam drive by manual transfer handle and also signals an ATS controller to disconnect electric power to a gear motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A & 1B front views illustrating an automatic transfer switch of the prior art;

(2) FIG. 2 an example of an interlock mechanism of the prior art FIG. 3 is a perspective view illustrating an embodiment of the present invention using 3-pole MCCB;

(3) FIG. 4 is a three-dimensional, exploded view of the current invention;

(4) FIG. 5 is a partial, exploded view illustrating the connection between the gear motor, ratchet, cam drive mechanism, and manual transfer handle

(5) FIGS. 6 A & 6B perspective views showing MCCB 1 (6A) and MCCB 2 (6B) mounted in their Bases, their Toggle Levers and Fulcrum Points, Rear Crossbars and Opening Springs;

(6) FIGS. 7 to 10 schematic views illustrating operation of the Cam Drive Mechanism and Stored Energy Opening Springs on the toggle levers;

(7) FIG. 11 is a perspective view of the Controller and MCCB position micro switches in the invention;

(8) FIGS. 12 to 14 are schematic diagrams illustrating the operation of the Mechanical interlock bar and MCCB 1 and MCCB 2;

(9) FIGS. 15 & 16, top views illustrating the locking device of this invention,

(10) FIGS. 17 & 18 are schematic views showing operation of the Toggle Levers closing MCCB position Micro Switches

DETAILED DESCRIPTION OF CURRENT INVENTION

(11) Referring to FIG. 3 the present invention is an automatic transfer switch (ATS) with two MCCB or MCS mounted back-to-back for connecting a load to a Normal power source 31 and Standby power source 32.

(12) MCCB provide over current and short circuit trip protection. MCS are without overload protection or short circuit trip protection. Because the structure of the MCCB and MCS used in this embodiment have the same shape and dimensions, are toggled in exactly the same way, and use the same interlock device, this description and drawings will refer to both MCCB and MCS as “MCCB” to avoid unnecessary repetition of these terms for the same operation and structures.

(13) Continuing to refer to FIG. 3, a Controller 8 is integrated with the ATS in this embodiment to monitor Normal power source 31 and Standby power source 32 and execute automatic transfer of power when Normal power fails and retransfer to the Normal power source when it is restored. Controller 8 has a Controller Display screen 81 for displaying position of each MCCB and the status of each power source. The ATS has a Front Cover 5 which also covers the Controller Display Screen 81.

(14) Structure

(15) Referring to FIG. 3 and FIGS. 6A & 6B, MCCB 1 41 and MCCB 2 42 are mounted in separate Bases 70, 71 respectively. These Bases for each MCCB attach to a Mounting Plate 75 in a back-to-back orientation with the toggles of both MCCB facing outward.

(16) Referring to FIGS. 3 & 4, Lugs 46 at the top of MCCB 1 41 are for connecting the ATS to a Normal Power source 31. Lugs 47 at the top of MCCB 2 42 are for connecting to a Standby power source 32.

(17) The poles on the load sides of MCCB 1 41 and MCCB 2 42 are electrically connected by horizontally-mounted Bus Bars 45 with 2-pole, 3-pole, or 4-pole models of MCCB. Three-pole MCCB are shown in the drawings FIGS. 3 & 4. Lugs 48 on the bus bars are to connect the ATS to a load.

(18) With Reference to FIG. 4 and FIGS. 6A & 6B, rectangular-shaped Toggle Levers 63, 66 extend around MCCB 1 41 and MCCB 2 42 to contact the toggle on the front of each MCCB. Roller followers 61, 64 on Rear Crossbars 631, 632 on the Toggle Levers 63, 66 extend to make contact with a Cam Drive Mechanism 52. Toggle Levers 63, 66 transmit the closing force of Cam Drive Mechanism 52 through the leverage of Fulcrum Points 62, 65 located on the sides of MCCB Bases 70, 71 respectively. Toggle levers 63, 66 differ only in location of roller follower on the rear crossbar and are identical in function.

(19) With reference to FIG. 6A, Toggle Lever 1 63 for MCCB 1 41 consists of a Rear Crossbar 631 with attached Roller Follower 61, a set of Stored Energy Opening Springs 43, a set of Fulcrum points 62 on each side of the its MCCB Base 70, and the Toggle Lever 63 contacting the toggle of MCCB 1 41.

(20) With reference to FIG. 6B, MCCB 2 42 is shown. The same type of structures used to toggle MCCB 1 41 are used to toggle MCCB 2 42 and are arranged in a mirror image of the cam driven structures from MCCB 1 41. Mechanical Interlock Device 7 is also shown in FIG. 6B.

(21) With Reference to FIG. 5 the Cam Drive Mechanism 52 consists of two Snail/drop cams 520, 521, which drive Roller Followers 61, 64 extending from rear crossbars of Toggle Lever 1 63 and Toggle Lever 2 66 respectively. Snail/drop cams 520, 521 are identical in shape and have a lower surface that rises to a peak surface when rotated in the clockwise direction before dropping sharply back to a lower surface. Snail/Drop Cams 520, 521 are installed coaxially but opposite in orientation with the peak surfaces of the two cams 180 degrees out of phase.

(22) The orientation of the peak surfaces of Snail/Drop Cam 1 520 and Snail/Drop Cam 2 521 prevents both Toggle Levers 63, 66 from transmitting a closing input to MCCB 1 41 and MCCB 2 42 at the same time and connecting both Normal power 31 and Standby power source 32 at the same time. The orientation of the peak surface cams also provides both MCCB open positions in the fixed transfer sequence (see FIGS. 7 & 9). The both MCCB open positions are between the Normal power MCCB closed position (FIG. 8) position and the Standby power MCCB closed position (FIG. 9) in the fixed transfer sequence.

(23) Roller follower 61 on the rear crossbar of Toggle Lever 1 63 is in contact with the surface of Snail/drop Cam 1 520 in the Cam Drive Mechanism 52. Roller follower 64 on the rear crossbar of Toggle Lever 2 66 is in contact with the surface of Snail/Drop Cam 2 521 in the Cam Drive Mechanism 52.

(24) With reference to FIG. 5, Cam Drive Mechanism 52 can be rotated manually with a Manual Transfer Handle 54 or automatically by a Motor 53 that is operated by Controller 8.

(25) Motor 53 is a unidirectional gear motor with a Motor Shaft 531 that inserts into Ratchet 51 to rotate the Cam Drive Mechanism 52.

(26) Ratchet 51 is a one-way ratchet with multiple Ratchet gear teeth 511 that engage the Cam Drive Mechanism 52 when turned clockwise by the Motor 53. The arrangement and direction of the Ratchet Gear Teeth 511 declutches the Ratchet 51 from the Motor Shaft 531 when Cam Drive Mechanism 52 is rotated by the Manual Transfer Handle 54. This declutching allows manual operation of the Cam Drive Mechanism 52 without engaging the Gear Motor Shaft 531 and thereby rotating the Gear Motor 53.

(27) Operation

(28) FIGS. 7, 8, 9, and 10 reveal in detail the operation of the Cam Drive Mechanism 52 and the Stored Energy Opening Springs 43, 44 to operate Lever Toggles 63, 66 to open and close MCCB 1 and MCCB 2 through the fixed sequence of four positions:

(29) 1) Both MCCBs open position (FIG. 7)

(30) 2) Normal power MCCB closed position (FIG. 8)

(31) 3) Both MCCBs open position (FIG. 9)

(32) 4) Standby power MCCB closed position (FIG. 10)

(33) Further Rotation returns the ATS to Position 1) to repeat this sequence.

(34) FIG. 7 shows Position 1) Both MCCBs open position

(35) Roller follower 61 on the Rear Crossbar 631 of Toggle Lever 1 rests on the lower surface of Snail/drop Cam 1 520 and no closing force is transmitted through Toggle Lever 1 63. Roller follower 64 on the Rear Crossbar 661 of Toggle Lever 2 66 rests on the lower surface of Snail/drop Cam 2 521 and no closing force is transmitted to Toggle Lever 2 66. Both sets of Stored Energy Opening Springs 43, 44 on Toggle Lever 1 63 and Toggle Lever 2 66 are in a contracted state and both MCCB 1 41 and MCCB 2 42 are open.

(36) FIG. 8 shows Position 2) Normal power MCCB closed position When Cam Drive Mechanism 52 rotates clockwise from Position 1) Roller Follower 61 on the rear crossbar of Toggle Lever 1 63 rotates to the Peak surface of Cam 1 520 raising Rear Crossbar 632 on Toggle Lever 1 providing a closing force to the toggle on MCCB 1 41 through the leverage of Fulcrum points 62.

(37) The Stored Energy Opening Springs 43 on the Rear Crossbar of Toggle Lever 1 63 expand and store energy in this closing process. Roller follower 64 on the Rear Crossbar 661 rotates to a further point on the surface of Cam 2 521 but no closing force is transmitted to Toggle Lever 2 66. Opening springs 44 on rear crossbar of Toggle Lever 2 remain in a contracted state. MCCB 1 41 is closed and MCCB 2 42 is open.

(38) FIG. 9 shows Position 3) both MCCBs open position When Cam Drive mechanism 52 rotates clockwise from the Normal power MCCB closed position Roller Follower 61 on the rear crossbar of Toggle Lever 1 drops sharply to the lower surface of Cam 1 520 removing any closing force through Toggle Lever 1 63. The Stored Energy Opening Springs 43 connected to the Rear Crossbar 631 of Toggle Lever 1 contract releasing stored energy and pulling open MCCB 1 41 through the leverage of Fulcrum points 62. Roller follower 63 on the rear crossbar rotates to a further point on the surface of Snail/Drop Cam 2 521 and no upward force is given to Toggle Lever 2. Stored Energy Opening springs 44 on the rear crossbar of Toggle Lever 2 66 remain in a contracted state. MCCB 1 and MCCB 2 are both open.

(39) FIG. 10 shows Position 4) Standby power MCCB closed position When Cam Drive Mechanism 52 rotates clockwise from the previous both MCCB open position in FIG. 9 Roller Follower 64 on the rear crossbar of Toggle Lever 2 66 rotates to the peak surface of Snail/drop Cam 2 521 raising the rear crossbar of Toggle Lever 2 66 providing a closing force to the toggle on MCCB 2 through the leverage of Fulcrum points 62.

(40) Stored Energy Opening Springs 44 on the Rear Crossbar 661 of Toggle Lever 2 expand to store energy in the closing process. Roller follower 61 on the rear crossbar rotates to a further point on the surface of Snail/Drop Cam 1 520 and no upward force is given to Toggle Lever 1. Stored Energy Opening Springs 43 on rear crossbar of Toggle Lever 1 remain in a contracted state. MCCB 1 41 is open and MCCB 2 42 is closed.

(41) Further rotation of the Cam Drive Mechanism 52 from the Standby power MCCB closed position will return the ATS to the first both MCCB open position in FIG. 7 and this cycle will repeat as the Cam Drive Mechanism 52 is rotates either electrically by the gear motor or manually with the Manual Transfer Handle.

(42) Referring to FIG. 11, an electronic Controller 8 is integrated with the transfer switch in this embodiment. The Controller 8 monitors the status of Normal Power Source 31 and Standby power source 32, controls the automatic transfer process and provides electric power to the Gear Motor 53. Controller 8 has a Controller Display screen 81 for displaying position of each MCCB and the status of each power source.

(43) Mechanical Interlock

(44) With reference to FIGS. 12, 13, & 14, a Mechanical Interlock Bar 7 made of a non-conductive material inserts into openings on the rear side of each MCCB. Mechanical Interlock Bar 7 is pushed outward by a mechanical element connected to the contacts when an MCCB closes. Mechanical Interlock Bar 7 is pushed outward by a closing MCCB and into the opposite MCCB physically preventing that switch from closing and preventing Normal and Standby power sources from connecting at the same time.

(45) With reference to FIGS. 5, 15 &16, a Manual Transfer Handle 54 manually rotates the Cam Drive Mechanism 52 clockwise direction to open and close MCCB 1 and MCCB 2 in the fixed sequence shown in FIGS. 7, 8, 9, & 10.

(46) Motor Shaft 531 inserts into a Ratchet 51 to transmit rotating force to Cam Drive Mechanism 52. The orientation of Ratchet Teeth 511 allows the Manual Transfer Handle 54 to rotate the Cam Drive Mechanism 52 without engaging Motor Shaft 531. When Cam Drive Mechanism 52 is rotated by Manual Transfer Handle 54 the direction of the Ratchet Teeth 511 causes the Ratchet 51 to declutch from the Motor Shaft 531 preventing manual rotation of the Gear Motor 53.

(47) With Reference to FIGS. 15 & 16, a Locking Device 55 prevents any changes from any position by either manual or automatic operation. Locking Device 55 can lock the ATS in any of the four positions in the fixed transfer sequence (see FIGS. 7, 8, 9, and 10)

(48) Locking Device 55 consists of a Locking Clip 551 to block rotation of the Manual Transfer Handle 54. Pushing in the Locking Clip 551 compresses a spring mechanism that pushes the clip outward. Locking Clip 551 has a hole to attach a padlock to block the return of the clip by two studs extending from the Front Cover 5 of the ATS.

(49) Pushing Locking Clip 551 inward opens a Locked Position Micro Switch 552 to signal the Controller 8 that the switch is locked and prevent automatic operation. The opening of Locked Position Micro Switch 552 will cause Controller 8 to remove power to the Gear Motor 53 and ignore any inputs through buttons on the Controller 8.

(50) When the padlock is removed or Locking Clip 551 is released the compressed spring mechanism expands pushing Locking Clip 551 outward, unblocking the Manual Transfer Handle 54. The Locked Position Micro Switch 552 closes in this process enabling power to the Gear Motor 53 and inputs to Controller 8 for automatic operation of the ATS.

(51) With reference to FIGS. 11, 17 & 18, a pair of MCCB Position Micro switches 82 are associated with MCCB 1 41. A second pair of MCCB Position micro switches 83 are associated with MCCB 2 42. These micro switches are located on Controller 8 to detect the open or closed position of each MCCB respectively. Controller 8 has a Display screen 81 for displaying position of each MCCB and the status of each Normal power source 31 and Standby Power Source 32.

(52) One micro switch in each pair 82, 83 provides MCCB position information to Controller 8. The other micro switch in each pair provides an auxiliary output of MCCB position for use by external devices.

(53) Both pairs of MCCB Position Micro switches 82, 83 are normally open and provide a closed signal when compressed by the rear crossbar of Toggle Lever 1 63 or Toggle Lever 2 66 as shown in FIGS. 17 & 18.

(54) FIG. 17 shows ATS in a both MCCB open position.

(55) FIG. 18 shows the MCCB 1 41 closed position. The rear crossbar Toggle Lever 1 63 closes MCCB Position Micro Switches 82. Toggle Lever 2 remains in the open position and MCCB Position Micro Switches 83 remain open.

LIST OF REFERENCE NUMERALS

(56) 1 . . . prior art ATS (side-by-side mounting of MCCB) 11 . . . Bi-directional Motor Shaft (prior art) 12 . . . Bi-directional Toggle lever (prior art) 13 . . . Normal Power MCCB (prior art) 14 . . . Standby Power MCCB (prior art) 15 . . . Bus bar (prior art) 16 . . . Bus bar (prior art) 21 . . . Normal Power source (prior art) 22 . . . Standby Power source (prior art) 31 . . . Normal Power source 32 . . . Standby Power source 41 . . . MCCB 1 (Normal Power MCCB) 42 . . . MCCB 2 (Standby Power MCCB) 43 . . . Stored Energy Opening Springs for Toggle Lever 1 44 . . . Stored Energy Opening Springs for Toggle Lever 2 45 . . . Bus bars connecting load sides of MCCB 1 and MCCB 2 46 . . . Lugs connecting ATS to Normal power source 47 . . . Lugs connecting ATS to Standby power source 48 . . . Lugs connecting bus bars to load 5 . . . Front Cover of ATS 51 . . . Ratchet 511 . . . Ratchet gear teeth 52 . . . Cam Drive Mechanism 520 . . . Snail/drop Cam 1 521 . . . Snail/drop Cam 2 53 . . . Motor 531 . . . Gear Motor shaft 54 . . . Manual Transfer Handle 55 . . . Locking Device 551 . . . Locking Clip 552 . . . Locked Position Micro Switch 61 . . . Roller follower on Toggle Lever 1 62 . . . Fulcrum points for Toggle Lever 1 63 . . . Toggle Lever 1 631 . . . Rear Crossbar of Toggle Lever 1 64 . . . Roller Follower of Toggle Lever 2 65 . . . Fulcrum points for Toggle Lever 2 66 . . . Toggle Lever 2 661 . . . Rear Crossbar of Toggle Lever 2 7 . . . Mechanical Interlock Bar 70 . . . Mounting Base for MCCB 1 71 . . . Mounting Base for MCCB 2 75 . . . Mounting Base Plate for MCCB Bases 8 . . . Controller 81 . . . Controller Display Screen 82 . . . Position Micro switches for MCCB 1 83 . . . Position Micro switches for MCCB 2 D Direction of rotation of cam mechanism