Phase reversal switch mechanism

Phase reversal switch apparatus for a three-phase high-current isolated phase bus circuit includes a non-reversing phase switch, and two groups of two reversing phase switches. The apparatus also includes a phase reversal mechanism having a rotatable operating shaft with a drive lever, a non-reversing lever, and two reversing levers coupled thereto. Locking and drive couplings are selectively engaged with the levers and operated by a shift actuator and a switch actuator to selectively operate the non-reversing switch and the first and second reversing switches to effect a phase sequence reversing operation in a secure and efficient manner.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to multi-phase electrical switch apparatus and, more 
particularly, to apparatus utilizing multi-phase electrical switches for 
providing phase reversal of associated multi-phase electrical circuits. 
2. Description of the Prior Art 
Certain applications in the generation, transmission, distribution, and 
utilization of electrical energy require the reversal of phases of a 
multi-phase electrical circuit. For example, pumped-storage electrical 
generation projects utilize a dual mode dynamoelectric machine in the 
motor mode to pump water into a reservoir to increase the head behind a 
dam. This pumping occurs during off-peak hours when the total load on the 
utiliy grid is low. When the demand for electrical energy on the grid 
increases, the reservoir is drained to drive the dynamoelectric machine in 
the generator mode to produce electric power which is supplied to the 
grid. The transformation between motor mode and generator mode is 
accomplished by reversing the phase connections to the machine. To provide 
this phase reversal in a three-phase system generally requires a five-pole 
switch and a mechanism for operating the poles in the proper sequence. 
Such a mechanism must meet a variety of requirements. The mechanism must be 
adaptable to accommodate variations in the phase-to-phase spacing 
encountered in various mounting configurations and it should be positively 
linked o all switches at all times and at all positions of travel of the 
switches from the fully opened position to the fully closed position. This 
is to prevent accidental opening or closing of the switches due to 
vibrations or gravity. During the phase-reversal cycle, one of the 
switches must open fully and reclose fully. Furthermore, all five switches 
should be completely open at the mid-point of the phase reversal cycle; 
that is, no switches should be opening while the others are closing. It is 
desirable to provide a mechanism which meets these requirements in an 
efficient, economical manner. 
SUMMARY OF THE INVENTION 
In accordance with the principals of the presen invention, there is 
provided a phase reversal switch assembly which includes first and second 
groups of reversing phase switches, a non-reversing phase switch, a 
rotatable operating shaft, and switch actuator means operable between open 
and closed positions to provide motive power to open and close the 
switches. A drive lever is connected to the switch actuator means and is 
movably coupled to the shaft so as to permit torque to be transmitted to 
the shaft at all times. A non-reversing switch lever is connected to the 
non-reversing phase switches and is movably coupled to the shaft so as to 
permit torque to be transmited from the shaft to the non-reversing switch 
lever at all times. First and second reversing switch levers movably 
coupled to the shaft are also provided to respectively operate the first 
and second groups of reversing switches between open and closed positions. 
Drive coupling means are provided for selectively engaging with the first 
and second reversing switch levers and are operable when engaged to 
transmit torque in the shaft to one of the reversing switch levers. 
Locking coupling means also selectively engageable with the first and 
second reversing switch lever means are provided which are operable when 
engaged to lock one of the reversing switch levers in an open position. 
The relative positions of the drive and locking couplings prevents 
reversing the engagement during the switching operation. Link means are 
coupled to the locking and drive coupling means and to the first and 
second reversing switch lever means and are operable between first and 
second positions by a shift actuator to cause the locking coupling means 
to engage one of the reversing switch lever means and the drive coupling 
means to engage the other of the reversing switch lever means. Operation 
of the link means to the first position is operable to cause the drive 
coupling means to engage the first reversing switch lever means and the 
locking coupling means to engage a second reversing switch lever means 
such that subsequent operation of the switch actuator to the closed 
position is operable to cause the operating shaft to transmit torque to 
the first reversing switch lever means and cause the first group of 
reversing phase switches and the non-reversing phase switch to move to the 
closed position. 
Operation of the link means to the second position is operable to cause the 
drive coupling means to engage the second reversing switch lever means and 
the locking coupling means to engage the first reversing switch lever 
means such that subsequent operation of the switch actuator means to the 
closed position is operable to cause the second group of reversing phase 
switches and the non-reversing phase switch to move to the closed position 
.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, in which corresponding reference characters 
refer to corresponding elements, there is shown in FIG. 1 an 
electromechanical schematic diagram of a three-phase five-pole switch 
assembly in the CLOSE position, normal phase sequence configuration. The 
assembly 10 includes five identical phase switches 12, 14, 16, 18 and 20 
which may be, for example, the type disclosed in copending application 
Ser. No. 219,716, filed Dec. 24, 1980 by Zwillich et al. now U.S. Pat. No. 
4,339,635 and assigned to the assignee of the present invention. These 
switches are telescoping disconnect switches adapted to be connected in 
isolated phase bus configurations to carry continuous current levels on 
the order of 25,000 amperes at a potential of approximately 16,000 volts. 
Although the assembly 10 is described in connection with disconnect 
switches of the type described in the aforementioned Zwillich et al. 
application, it is contemplated that other types of disconnect switches 
could be utilized. 
The switch assembly 10 includes three input terminals 22, 24, and 26 
carrying input phases A, B, and C, respectively. The assembly 10 also 
includes three output terminals 28, 30, and 32 which in the normal 
configuration of the switch will supply phases A, B, and C, respectively. 
In the reverse configuration of the switch, the output terminals 28, 30, 
and 32 will supply phases B, A, and C, respectively; that is, the phases 
of output terminals 28 and 30 are interchanged. 
Terminal 32 connected to switch 16 always supplies phase C whenever switch 
16 is closed. Thus, the switch 16 is referred to as the non-reversing 
switch. The other switches 12, 14, 18, and 20 are referred to as reversing 
switches and are separated into two groups; switch 12 and switch 14 being 
referred to collectively as the first group of reversing switches and the 
switches 18 and 20 being referred to collectively as the second group of 
reversing switches. Correspondingly, phase C is referred to as the 
non-reversing phase whereas phases A and B are referred to as the 
reversing phases. Each group of reversing switches is actuated in common, 
that is, switch 12 and switch 14 are either simultaneously open or 
simultaneously closed. Similarly, switches 18 and 20 are either 
simultaneously open or simultaneously closed. Each group of reversing 
switches is thus actuated together. 
A complete phase reversal cycle of the assembly 10 is illustrated by the 
FIGS. 1, 2 and 3. In FIG. 1, the non-reversing phase switch 16 and the 
first group of reversing phase switches 12 and 14 are all closed, whereas 
the second group of reversing switches 18 and 20 is open. To initiate a 
phase reversal cycle, a switch actuator, shown schematically as 34, 
operates upon a mechanism 36. The mechanism 36 includes a combination 
drive and non-reversing switch lever 38 rigidly connected to an operating 
shaft 40. Operation of the switch actuator 34 to produce a rectilinear 
motion causes the combination lever 38 to rotate and transmit torque to 
the operating shaft 40. Rotation of the combination lever 38 is also 
operable to actuate the non-reversing switch 16 between open and closed 
positions. Separate drive and non-reversing switch levers could be 
provided to perform the functions of the combination lever 38. 
The mechanism 36 also includes first and second reversing switch, or phase, 
levers 42 and 46, respectively, which are also coupled to the shaft 40. 
Unlike the combination lever 38, however, they are not coupled to the 
shaft 40 so as to permit torque to be transmitted from the shaft to the 
levers at all times. Rather, a shift actuator 48 operates a shift link 
shown schematically at 50 between NORMAL and REVERSE positions to 
selectively engage for torque transmission one or the other of the 
reversing switch levers 42 and 46 with the operating shaft 40, but not 
both of the levers 42 and 46. The lever 42 or 46 not so engaged is locked 
so as to maintain its corresponding group of reversing switches in the 
OPEN position. 
As can be seen in FIG. 2, the mid-point of the phase reversal cycle results 
in all switches 12, 14, 16, 18, and 20 being placed in the OPEN position, 
by operation of the switch actuator 34. The shift actuator 48 is then 
operated to the REVERSE position to engage the second reversing phase 
lever 46 with the operating shaft 40 and disengage and lock the first 
reversing phase lever 42. Thus, subsequent operation of the switch 
actuator 34 to the CLOSE position as shown in FIG. 3 results in rotation 
of the second reversing switch lever 46 and the combination lever 38 
(which is continuously engaged with the shaft 40) to cause the switches 
16, 18 and 20 to be operated to the CLOSE position while the switches 12 
and 14 remain locked in the OPEN position. It can thus be seen that the 
phase sequence configuration appearing at the output terminals 28, 30 and 
32 has been reversed. 
The operating mechanism 36 of the assembly 10 is shown more clearly in FIG. 
4A. As can be seen, the operating shaft 40 is free to both rotate and 
translate axially in a vertical direction as seen in the drawings. The 
shaft 40 extends through the combination drive and non-reversing switch 
lever 38. A spline 52 rigidly attached to the shaft 40 passes through a 
keyway in the combination lever 38 to ensure that the combination lever 38 
rotates with the shaft 40 at all axial positions thereof. 
The shaft 40 also extends through a pair of locking couplings 54a and 54b, 
and is free to rotate therewithin. The locking couplings 54a and 54b are 
connected by a link member 56 which rigidly supports a bearing 58 
surrounding the shaft 40. Attached to either side of the bearing 58 are a 
pair of drive couplings 60a and 60b fixedly attached to the operating 
shaft 40 to rotate and axially translate along with the shaft 40. Each of 
the levers 42, 46, and 38 are free to rotate but are constrained by 
portions of the connecting mechanism (not shown) to prevent movement in a 
vertical direction as shown in the drawing. Thus, the operating shaft 40, 
the locking couplings 54a and 54b, the bearing 58, the drive couplings 60a 
and 60b, and the link member 56 all move as a unit in the vertical 
direction when so operated by the shift actuator 48. Rotation of the 
operating shaft 40 causes corresponding rotation of the combination lever 
38, the drive couplings 60a and 60b, and either the first reversing switch 
lever 42 or the second reversing switch lever 46, depending on which of 
these levers is engaged by one of the drive couplings 60a and 60b as 
determined by the axial position of the operating shaft 40. 
FIG. 5A is a sectional view of the drive coupling 60 taken along the line 
V--V of FIG. 4A. As can be seen, the coupling 60b includes three 
symmetrically disposed teeth 61. The teeth 61 mate with corresponding 
recesses in the second reversing switch lever 46 to allow the drive 
coupling 60b to engage the lever 46 as shown in FIG. 4B. Operation of the 
switch actuator 34 to the CLOSE position rotates the drive coupling 60b 
90.degree. to the position shown in FIG. 5b. 
The locking couplings 54a and 54b and lever 42 also have corresponding 
teeth and recesses similar to those described. It can be seen that since 
there are an odd number of teeth and recesses and that the switch 
positions are 90.degree. apart, the drive couplings 60a and 60b cannot 
engage a reversing switch lever unless both the drive coupling and 
reversing switch lever are in the same position (either OPEN or CLOSE). 
Different rotation angles and teeth arrangements could, of course, be 
used, but more secure operation is provided if the arrangements are such 
as to provide the lock-out feature as described above. 
The operation of the mechanism 36 in effecting a phase reversal cycle will 
now be described in relation to FIGS. 4A and 4B. FIG. 4A shows the 
condition of the mechanism 36 when all of the switches 12, 14, 16, 18, and 
20 are open prior to closing to produce a normal phase output on the 
terminals 28, 30, and 32. As can be seen, the lower locking coupling 54b 
is engaged with the second reversing switch lever 46. The upper drive 
coupling 60a is engaged with the first reversing switch lever 42. 
Operation of the switch actuator 34 (FIG. 1) produces a linear force on 
the combination drive and non-reversing switch lever 38 which in turn 
produces a torque upon the operating shaft 40 through the spline 52. The 
shaft 40 then rotates under the action of the switch actuator 34 
approximately 90.degree.. Since the lower locking coupling 54b is engaged 
with the second reversing switch lever 46, this lever remains locked in 
the same position as shown in FIG. 4A, causing the corresponding second 
group of reversing switches to remain locked in the OPEN position. The 
upper drive coupling 60a rotates with the shaft 40, and since the drive 
coupling 60a is engaged with the first reversing switch lever 42, this 
lever also rotates about 90.degree. with respect to the operating shaft 
40. This causes the first connecting rod 43 (FIG. 1) to actuate the first 
group of reversing switches 12 and 14 to the CLOSED position. Since the 
lever 38 actuates the non-reversing switch 16, this switch is also 
operated to the CLOSE position simultaneously with the switches 12 and 14. 
The assembly 10 then corresponds to the configuration shown in FIG. 1. 
To effect a reversal of the phases appearing on the terminals 28, 30 and 
32, the switch actuator 34 is operated to the OPEN position rotating the 
operating shaft 40 and causing the mechanism 36 to once again assume the 
positions shown in FIG. 4A. All of the switches 12, 14, 16, 18 and 20 are 
now in the OPEN position, as shown in FIG. 2. Next, the shift actuator 48 
is operated to the REVERSE position to move the shaft 40 axially in a 
downward direction as shown in FIG. 4A to assume the configuration shown 
in FIG. 4B. As can be seen therein, the upper locking coupling 54a engages 
the first reversing switch lever 42 and the lower locking coupling 54b 
disengages the second reversing switch lever 46. Correspondingly, the 
upper drive coupling 60a disengages the first reversing switch lever 42 
and the lower drive coupling 60b engages the second reversing switch lever 
46. The lever 38 remains engaged with the operating shaft 40 since the 
spline 52 is of sufficient length to maintain engagement at all axial 
positions of the shaft 40. 
To complete the phase-reversal operation, the switch actuator 34 is now 
operated to the CLOSE position. This causes the combination lever 38 to 
rotate and close the non-reversing switch 16. Rotation of the lever 38 
also transmits torque through the spline 52 to rotate the shaft 40. Since 
the first reversing switch lever 42 is engaged by the upper locking 
coupling 54a it remains locked in the OPEN position. The second reversing 
switch lever 46, however, is engaged by the lower drive coupling 60b. 
Since this coupling is rigidly connected to the shaft 40, rotation of the 
shaft 40 causes rotation of the second reversing switch lever 46 
simultaneously with rotation of the combination lever 38. The lever 46 
operates the second connecting rod 45 to move the second connecting rod 45 
to move the second group of reversing switches 18 and 20 to the CLOSE 
position simultaneously with the switch 16. The assembly 10 thus assumes 
the condition shown in FIG. 3, wherein the terminals 28, 30, and 32 now 
supply phases B, A, and C, respectively. This completes a phase reversal 
operation. 
FIGS. 6A and 6B are similar to FIGS. 4A and 4B, but illustrate a first 
alternative embodiment 36a of the operating mechanism 36. In the mechanism 
of 36a, the operating shaft 40 is free to rotate, but is prevented from 
moving in the axial direction. The locking couplings 54a and 54b are 
fixedly mounted to structure (not shown) to prevent both rotational and 
axial motion. Similarly, the combination drive and non-reversing switch 
lever 38 is supported by a connecting linkage (not shown) to permit 
rotational movement but prevent any motion in the axial direction. The 
first and second reversing switch levers 42 and 46 are rigidly connected 
by the shift link 56 and are operated on by the shift actuator 48 to move 
in an up and down direction as shown in FIGS. 6A and 6B. In a manner 
similar to the previously described embodiment, a normal phase 
configuration on the terminals 28, 30 and 32 of FIG. 1 is achieved by 
operation of the switch actuator 34 to the CLOSE position with the shift 
actuator 48 in the NORMAL configuration positioning the first and second 
reversing switch levers 42 and 46 and the shift link 56 in the position 
shown in FIG. 6A. Such operation of the switch actuator 34 will result in 
rotation of the combination lever 38 and first reversing switch lever 42 
to close the switches 12, 14, and 16. The switches 18 and 20 which are 
driven by the second reversing switch lever 46 remain locked in the OPEN 
position due to the engagement of the switch 46 with the lower locking 
coupling 54b as shown in FIG. 6A. 
To perform a phase reversal operation, the switch actuator 34 is operated 
to the OPEN position returning the mechanism 36a to the configuration 
shown in FIG. 6A. The shift actuator 48 is then operated to move the 
mechanism 36a from the NORMAL condition shown in FIG. 6A to the REVERSE 
condition shown in FIG. 6B. As can be seen therein, the first and second 
switch levers 42 and 46 and the shift link 56 have been moved in an upward 
direction to the position shown. The first reversing switch lever 42 is 
now engaged by the upper locking coupling 54a and the second reversing 
switch lever 46 engaged by the lower drive coupling 60b connected to the 
combination drive and non-reversing switch lever 44. Subsequent operation 
of the switch actuator 34 from the OPEN to the CLOSE position will result 
in rotation of the lever 44 and the second reversing switch lever 46 to 
close switches 16, 18, and 20. The first reversing switch lever 42 remains 
in the position shown in FIG. 6B, resulting in the switches 12 and 14 
being locked in the OPEN position. 
A second alternative embodiment of the invention may be implemented using a 
mechanism 36b as shown in FIGS. 7A and 7B. Mechanism 36b operates 
according to the same principles as the mechanisms 36 and 36a, but in a 
slightly different manner. A stationary shaft 70 is mounted parallel to 
the operating shaft 40. Retaining rings 72 secured to the shaft 70 support 
the combination drive and non-reversing switch lever 38 and the first and 
second reversing switch levers 42 and 46, permitting these levers to 
rotate but preventing up and down motion as seen in FIGS. 7A and 7B. The 
operating shaft 40 is axially movable in an up and down direction in 
response to operation of the shift actuator 48. Attached to the shaft 40 
are the locking couplings 54a and 54b which are prevented from rotating by 
sliding collars 74a and 74b which slide up and down along the shaft 70. 
The operating shaft 40 is, however, free to rotate within the locking 
couplings 54a and 54b. Also attached to the shaft 40 is a drive spline 76 
which performs the function of the drive couplings 60a and 60b of the 
mechanism 36 and 36a. The spline 76 is engageable with keyways formed in 
the levers 42, 38, and 46. As can be seen in FIGS. 7A and 7B, the spline 
76 is engaged with the keyway of the lever 38 in all positions of the 
operating shaft 40. When the shift actuator 48 is in the NORMAL position, 
the drive spline 76 engages the first reversing switch lever 42. When the 
shift actuator 48 is in the REVERSE position, the drive spline disengages 
the lever 42 and engages the lever 46. A phase reversal operation can be 
accomplished in the manner similar to that described with regard to the 
mechanisms 36 and 36a. It can be seen therefore that the present invention 
provides a phase reversal switch assembly which achieves the stated 
requirements in an efficient and economic manner.