I.
B.
694C694-02
CD
Manual Charge Handle
@ Manual Charge Handle Socket
@ Front Crank Assembly
0 Pivot Pin
@ Mounting Bracket
@ Rear Crank Assembly
(j) Crank Pin
@ Manual Charge Cams (3)
@ Crank Shaft
@Claw
Stop
Figure 4-3 Manually Operated Spring-Charging
Mechanism Details
Closing springs can be charged manually by using the
short, front mounted emergency charging handle. The
length of this charging handle is significantly shorter
than its manual version. This is one way
to
quickly iden-
tify a manually
or
power operated circuit breaker. The
manual charging mechanism on a power operated cir-
cuit breaker operates on a ratchet principle, requiring 10
to 12 handle pumping operations to completely charge
the springs. When charged, a definite metallic "click" is
heard and the spring charge indicator on the front con-
trol panel will show "Spring Charged." Do not try to force
the charging handle beyond this point.
Closing of the circuit breaker is accomplished electrically
by an electromagnet (spring release device) which lifts
the closing spring release latch. Like the manually operat-
ed circuit breaker, the power operated circuit breaker can
also be closed manually by pushing the front control
panel close bar (Figure
3-3).
Effective
07
/97
Page
25
Power operated circuit breaker can be opened manually
or
electrically. Refer to paragraph 3-8.2 for details.
4-2.1 SPRING
CHARGE
MECHANISM
FOR
POWER
OPERATED
BREAKERS
The mechanism in a power operated circuit breaker is
graphically illustrated in Figure
4-4.
Figure 4-5 is a front view drawing showing the principal
parts of the spring-charging portion of this mechanism.
Some parts are omitted for clarity. Figure
4-6 shows in
greater detail the major parts of the spring-charge mecha-
nism in the two basic positions:
1.
Closing springs charged as viewed looking into right
end of crankshaft (Figure
4-6a)
2. Closing springs discharged partial view
Refer to Figure
4-5. The basic elements are mounted on
the crank shaft (8). This is a straight shaft with four flats
machined on it, and a crank arm (11) attached
to
each
end. Each crank arm connects to its closing spring (9)
by a formed spring end (10) in Figure 4-6b. The rear of
the springs anchor to the rear of the mechanism frame.
The crank arms
(11
), motor cutoff switch cam (7), close
cam (6) and two drive plates (25) have matching flats,
and are thus anchored to the crank shaft. The spring
charge indicator (12) ratchet wheel (17), oscillator (30),
and emergency charge device (26) do not have internal
flats, but are mounted on separate bushings and are
free to rotate on the crank shaft.
The motor crank shaft assembly (29), carrying a roller for
driving the oscillator, is pivoted in the right hand mecha-
nism side frame. The hold pawl (18) is mounted by means
of a pin on the mechanism side frame.
In
operation, rotation of the motor crank pushes the oscil-
lator arm counterclockwise to make the oscillator pawl
(28) push a tooth in the ratchet wheel (17), and rotate the
ratchet wheel slightly more than one tooth in the counter-
clockwise direction. The holding pawl snaps behind the
corresponding advanced tooth, and holds it against the
torque of the closing
springs while the oscillator arm
rotates back clockwise to catch another ratchet tooth.
Thus the ratchet wheel is rotated counterclockwise until
the ratchet wheel pin (21) engages the two drive plates
(25), which
in
turn rotate the crank shaft and crank arms
in the same direction until the arms are slightly past hori-
zontal dead center. Since the close cam (6) is rigidly
mounted on the crank shaft like the drive plates, it has
rotated the same amount as the plates. The close cam
carries as stop roller as shown in Figure
4-7b. Just after
Courtesy of NationalSwitchgear.com
To Next Page
Loading...
