Fused unitized combination starter

A multipole unitized motor starter is constructed of a common base having mounted thereon a disconnect switch, an electromagnetic contactor and a fuse unit connected in electrical series between the switch and contactor. The fuse unit is a plug-in device which is readily removable for service access and when operatively mounted is positioned to permit direct viewing of the switch contacts.

This invention relates to electrical switching apparatus in general, and 
more particularly, relates to a fused unitized combination motor starter. 
Pending U.S. application Ser. No. 681,243, filed Apr. 28, 1976 by F. W. 
Kussy et al. for a UNITIZED COMBINATION STARTER, discloses a compact 
unitized switching means, including a multipole electromagnetic contactor 
in series with a multipole circuit breaker having fault current responsive 
trip means. 
Pursuant to the instant invention, a unitized combination starter includes 
the series-connection of a multipole electromagnetic contactor, a 
multipole disconnect switch and a multipole fuse unit all mounted on a 
molded insulating base. The fuse unit is a plug-in device, which may be 
conveniently removed to gain access to the contact structure of the 
contactor. However, when the fuse unit is operatively mounted, it is 
positioned so that there may be direct viewing of the switch contacts. 
Each pole of the disconnect switch is provided with a movable contact arm 
that is mounted at one of its ends to a stationary pivot. The arm extends 
through a transverse aperture in an insulating tie-bar, which in turn is 
connected to a contact operating mechanism. The tie-bar encircles each 
contact arm to provide the only connection between the contact arms and 
their operating mechanisms. 
Accordingly, a primary object of the instant invention is to provide a 
novel construction for a combination motor starter. 
Another object is to provide a motor starter of this type in which a 
multipole electromagnetic contactor, a multipole disconnect switch, and a 
multipole fuse unit are arranged as a compact unitized structure. 
Still another object, is to provide a combination unit of this type having 
a removable plug-in fuse unit. 
A further object is to provide a combination unit of this type having novel 
means for connecting the movable contacts to the contact operating 
mechanism.

Now referring to the Figures. Enclosed electric switching apparatus 10 
(FIG. 1) includes generally rectangular enclosure 11 having an open front 
and provided with front cover 12 mounted on hinges 13 along cover edge 14. 
Disposed within enclosure 11 and secured to rear wall 14a thereof is 
unitized combination motor starter 15, including the series combination of 
disconnect switch 16, fuse unit 17, and electromagnetic contactor 18. The 
end of contactor 18 remote from switch 16 is connected in series with an 
array of three overloaded relays 19 (FIG. 2). 
Combination unit 15 is a three pole device having substantially identical 
current paths through each pole. With reference to FIG. 2 it is seen that 
the current path through each pole is from wire grip 42 on line terminal 
strap 43 to stationary switch contact 44, through movable contact arm 45 
to contact clip 46 at the end of contact arm 45 remote from stationary 
contact 44, through strap 47 having plug-in contact 48 at its free end in 
engagement with plug-in contact 49 at one end of strap 50 whose other end 
is connected to fuse clip 51, through fuse 52 to fuse clip 53 mounted at 
one end of strap 54 whose other end is provided with plug-in contact 55 in 
engagement with plug-in contact 56 at one end of strap 57, to stationary 
contactor contact 58, through bridging contact 60 and the other stationary 
contactor contact 59 to load terminal strap 61. The latter is connected to 
terminal 62 of overload relay 19. 
Disconnect switch 16 and electromagnetic contactor 18 are positioned in 
end-to-end relationship, and elements thereof are operatively positioned 
within cavities of common molded insulating base 65. Contactor 18 is 
provided with removable insulating front cover 66 having internal cavities 
at the rear thereof wherein contact means 58, 59, 60, together with arc 
extinguishing magnetic members 67 are disposed. U-shaped bail 68 is 
provided with inwardly turned ends 69, 69 which extend into complementary 
aligned apertures in opposite sides of cover 66 to pivotally mount bail 68 
to cover 66. As seen in FIG. 2, when cover 66 is in its operative 
position, the web 71 of bail 68 rests against the forward edges of reset 
plungers 72 for all three poles of overload relay 19. Reset rod 73 of 
handle mechanism 35 is positioned so that upon actuation thereof, its rear 
end engages bail arm 74 to pivot bail 68 counterclockwise with respect to 
FIG. 2 so that web 71 depresses all three overload relay reset plungers 
72, thereby resetting overload relay 19. 
Fuse unit 17 includes three fuses 52 mounted side by side to the front of 
molded insulating carrier 75 having longitudinally extending partitions 
176 disposed between fuses 52 (FIG. 4). Spring clips 51, 53 for holding 
the ferrules at opposite ends of fuses 52 are disposed on the front 
surface of carrier 75. Screw 76, 77 secure clips 53, 51, respectively, and 
straps 54, 50, respectively, to carrier 75 (FIG. 6). The latter is also 
provided with elongated aperture through which the plug-in contact 
formations 49, 55 of the respective straps 50, 54 extend to the rear of 
carrier 75. Apertures 78 through partitions 76 provide clearances for two 
screws 79 (FIG. 4) which are received by threaded apertures (not shown) in 
stationary contact carrier 79 for removably securing fuse unit 17 in its 
operative position of FIG. 2. In this position fuse unit plug-in contacts 
49, 55 are in operative engagement with the respective plug-in contacts 
48, 56 of switch 16 and contactor 18, respectively. Carrier 79 also 
provides clearance apertures 102 through which plug-in contact blades 48 
extend. Forward protrusions 103 of carrier 79 provide clearances between 
the pairs of contacts 48, 56 when fuse unit 17 is dismounted. 
The movable and stationary contact structures for each pole of disconnect 
switch 16 are very similar to the switch constructions shown in U.S. Pat. 
No. 3,684,849, issued Aug. 16, 1972 to M. V. Zubaty for a Heavy Duty 
Switch. More particularly, stationary contact clip 44 (FIG. 9) is a 
U-shaped member constructed of conducting spring material. The free ends 
of the U-arms 44a are reversely and inwardly bent, and are provided with 
apertures 44b which receive lips 81a protruding inwardly from the arms of 
U-shaped pressure spring 81 and surround clearance apertures 81b thereof 
(FIG. 12). Contact arm sections 44a are disposed between the arms of 
pressure spring 81 so that arm sections 44b are biased toward one another 
to firmly engage opposite sides of movable contact arm 45 at end 45a 
thereof (FIG. 10) when disconnect switch 16 is closed. The other end of 
contact arm 45 is provided with an aperture wherein hollow spring pin 82 
is snuggly fitted (FIG. 11). 
Contact clip 46 is of the same construction as stationary contact clip 44, 
and pressure spring 83 for contact clip 46 is of the same construction as 
pressure spring 81. The ends of pin 82 extend through the aligned 
apertures in pressure spring 83 to pivotally mount movable contact arm 45 
to contact clip 46, with the inwardly turned arms 46a of the latter firmly 
engaging opposite sides of contact arm 45. The outer sections of the arms 
for contact clip 46 are provided with apertures 46b which are aligned with 
the apertures in pressure spring 83 to permit insertion of pivot pin 82 
after contact arm 45 is entered between clip arm sections 46a. 
Each of the contact arms 45 projects through an individual transverse 
aperture 84, of elongated rectangular cross-section, extending through 
insulating tie bar 85 (FIG. 15). The end of rod 85 shown in FIG. 16 is 
adjacent to overcenter toggle contact operating mechanism 20 and is 
provided with threaded apertures 86 which receive screws 105 (FIG. 3) 
securing metal plate 87 (FIG. 18) to the end of tie bar 85 shown in FIG. 
16. Plate 87 is provided with arcuate slot 88 that is aligned with arcuate 
depression 89 in tie rod 85, and plate 87 is also provided with circular 
bearing aperture 91 that is aligned with circular depression 92 in tie bar 
85. For a reason which will hereinafter be seen, pins 25, 28 of contact 
operating mechanism 20 extend through apertures 91, 88, respectively, of 
plate 87. 
Auxiliary switch actuator member 93 (FIG. 4) is provided with arcuate slot 
94 through which the threaded portion of screw 95 extends into tapped hole 
96 in the end of tie bar 85 shown in FIG. 16. This end also includes 
bearing recess 97 coaxial with bearing recess 92. Recess 97 is aligned 
with a similar bearing recess (not shown) in actuator 93 and these 
recesses receive bearing pin 98 (FIG. 3) protruding from bracket 99 
secured to base 65. Thus, pins 25 and 98 constitute bearings for tie bar 
85. As will hereinafter become evident, screw 95 is tightened only enough 
to mount actuator 93 to permit relative movement of actuator 93 with 
respect to tie bar 85, about bearing pin 98 as a center. This assures that 
actuator 93 will not operate its associated axuiliary switches (not shown) 
until contacts 44, 45 are fully engaged. 
Manually operable spring power overcenter toggle contact operating 
mechanism 20 (FIG. 5) of disconnect switch 16 includes frame 21 extending 
forward from rear wall 14a of housing 11 and being secured thereto by 
fasteners (not shown) extending through frame leg 22. Mechanism 20 also 
includes actuator 23 mounted to frame 21 on stationary pivot 24 and having 
arcuate slot 126 which provides clearance for fixed pin 25. The latter is 
a pivot 25 for both tie-bar 85 and triangular toggle member 26. The other 
toggle member 27 is elongated and is pivotally connected at pin 28 to 
member 26. The end of member 27 remote from knee 28 extends through a 
guide aperture in bracket 29 which is pivoted to frame 21. Bracket 29 also 
provides a bearing surface for one end of coiled compression spring 31 
whose other end bears against shoulder 32 of member 27 so as to bias knee 
28 away from bracket 29. Elongated notch 33 at the rear of actuator 23 and 
pin 34 protruding from the side of member 26 into notch 33 combine to form 
a lost motion connection between toggle member 26 and actuator 23. Link 36 
extends rearward from handle mechanism 35 and is connected to actuator 23 
at pivot 37. 
As will hereinafter be seen, with operating mechanism 20 in the position of 
FIG. 5, the contacts 44, 45 of switch 16 are closed. The latter are opened 
by moving pin 28 forward or upward with respect to FIG. 5. This is 
accomplished by moving link 36 upward to pivot actuator 23 
counterclockwise. Actuator 23, in pivoting counterclockwise, moves free of 
toggle 26, 27 until the left edge 33a of notch 33 engage with pin 34. 
Continued counterclockwise movement of actuator 23 causes counterclockwise 
movement of toggle member 26 about its fixed pivot 25, thereby moving 
toggle knee 28 forward. At the point where knee 28 moves forward of a 
straight line between the fixed pivots 25, 29 for toggle members 26, 27, 
the force exerted by spring 31 drives pin 28 forward with a snap action 
until pin 28 reaches forward notch 38 in frame wall 39. The rear or 
contact closed position for pin 28 is established by notch 37 in frame 
wall 39. Rearward operation of link 36 to move actuator 23 clockwise moves 
the toggle knee 28 rearward for closing of switch 16. Coil compression 
spring 41 wound around rod 42 extending between fixed frame formation 21a 
and pin 43 on actuator 23, biases actuator 23 clockwise when positioned as 
in FIG. 5 and biases actuator 23 counterclockwise when pin 43 is moved 
forward of a line extending between pivots 21a and 24. Thus, it is seen 
that fused unitized combination starter 11 is of extremely compact 
construction, yet it is extremely simple to gain access to internal 
elements thereof for servicing. More particularly, the mounting of fuse 
unit 17 in front of contactor 18 substantially reduces the height of the 
required enclosure without appreciably increasing its depth requirement. 
The contactor contacts 58-60 are readily accessible merely by removing 
fuse unit 17 and cover 66. In order to replace contactor coil 101, it is 
merely necessary to remove fuse unit 17, cover 66 and contact structure 79 
of contactor 18. As seen in FIG. 2, with fuse unit 17 mounted in its 
operative position, when enclosure cover 12 is open, there is nothing to 
obscure visual observation of the free ends of movable contacts 45. 
Although this invention has been described with respect to its preferred 
embodiments, it should be understood that many variations and 
modifications will now be obvious to those skilled in the art, and it is 
preferred, therefore, that the scope of this invention be limited, not by 
the specific disclosure herein, but only by the appended claims.