Eaton Cutler-Hammer ATVSKDA30300XSU, Instructions Manual

Page: 14 / 40

I.B. ATS-V003
Page 8
Effective 6/98
3.2.1 VERTICAL DESIGN STEEL BASE PLATE
The steel base plate on the vertical design permits the
power panel to be moved vertically within the enclosure
to accommodate top or bottom cable entry (Figure 4-2).
Elongated holes on either side of the base plate insure
proper positioning. The bottom set of elongated holes
position the power panel higher in the enclosure, thus
permitting bottom cable entry. The top set of elongated
holes position the power panel lower in the enclosure for
top cable entry. Section 4 discusses equipment mount-
ing and load lug location in detail.
3.2.2 MAIN CONTACTS
The main contacts connect and disconnect the load to
and from the different power sources. High withstand
molded case switches are the main contacts for the
Normal and Emergency power sources in standard,
unmodified automatic transfer switches. Optional integral
thermal and short circuit protection in either or both
switching devices is, however, available (Figure 3-3 and
Section 3.5). These continuous duty switches are rated
for all classes of loads, open or enclosed. In addition,
they have high dielectric strength, heavy-duty switching
and withstand capabilities, and high interrupting capacity.
The switches incorporate positive, quick-make, quick-
break toggle mechanisms and De-ion arc chutes.
Vertically mounted switching devices are mechanically
and electrically interlocked to prevent the two sets of
main contacts from being closed simultaneously. The
load side contacts of each switching device are joined
with a bus bar assembly to form a common load termi-
nal location, either top or bottom (Figure 4-3).
Horizontally mounted switching devices are also
mechanically and electrically interlocked. The molded
case switches are kept trip-free in the closed position.
This permits thermal and short circuit protection to be
incorporated in either or both interrupters.
3.2.3 VERTICAL DESIGN TRANSFER MECHANISM
The transfer mechanism transfers between power
sources through a motor driven ratchet type operation.
A rotational motion is created on an indicator wheel by
the ratchet’s operation. The indicator wheel is attached
to rigid shafts which covert the rotary motion into vertical
linear motion. Opening and closing of the switching
devices is accomplished as a result of this vertical linear
motion. The transfer mechanism is mounted in front of
the molded case switches (Figure 3-1).
A solid steel shield attached to the ratchet assembly
permits viewing of the rotary switch position indicator
while restricting access to other parts of the power panel
(Figure 1-2).
3.2.4 HORIZONTAL DESIGN TRANSFER
MECHANISM
The horizontal design mechanism consists of a pivoting
rocker-arm lever which operates the switch handles as
the arm is moved by a rotating lever connected to the
transfer motor. A slide pin engaging a pivot in the rotat-
ing lever converts rotary motion to linear motion. Motor
limit switches are mounted externally to the molded case
switches and operated by the rotating lever. Each limit
switch is synchronized with its associated molded case
switch to operate when its switch closes (Figure 3-2).
Figure 3-3 Molded Case Switches Mounted in Vertical
Design (Transfer Mechanism Removed for Clarity)