Siemens-Allis FC-10008, Instructions Manual

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CIRCUIT BREAKER DESCRIPTION
A typical circuit breaker consists of primary dis·
connect, arc chute and operator sections. The primary
disconnect section contains the main contact which supplies
power to the load. The arc chute section dissipates the
power
arc
energy drawn during the opening of the main
contacts. The operator section contains the mechanism
used to close and open the main contacts. This mechanism
consists of a stored energy operator with Its associated
control circuitry.
ARC INTERRUPTION
Arc interruption is accomplished in free air at atmos·
pheric pressure with the aid of a self-induced, magnetic
blowout field and forced air draft. When the trip solenoid
is energized, load current is being carried by the main
contacts. As the contacts open, the main contacts part
first and the current is transferred to the arcing contacts.
When the arcing contacts part, an arc is established between
them.
The arc between the arcing contacts is transferred to
the arc runners through a transfer stack as the arcing con·
tacts
open. The transfer of the
arc to the arc runner
establishes full current
flow through the blowout coils,
setting up a strong magnetic field.
The magnetic
field,
accompanied by the
natural
t
herma
l effects
of
the h
e
a
t
e
d
arc,
tends to force the arc
upward into the ·barrier stack.
The large surfaces of the barrier stack cool
and
de-ionize the
arc,
while the V-shaped
slots in the stack reduce its
cross­
section and elongate
it, leading to rapid extinction. The arc
runners are made
of wide, heavy material for maximum
heat
dissipation
and
for minimum
metal
vapo
riza
tion
.
A puffer mechanism
provides a forced air draft
through the
main contact area. This aids the magnetic blow­
out field and natural thermal effects in
forcing the
ar
c
into
the barrier stack
for
easy e
xti
n
c
ti
o
n
.
OPERATOR
The breaker
is closed by the stored energy operator
straightening a toggle
in the four-bar linkage (Figure
7,
Item
12).
The operator
is
powered
by
pre
ch
arg
ed
springs
(stored energy).
Stored Energy Operator
The stored energy operator (Figure
3)
uses charged
springs to power the closing operation. Opening Is spring·
powered also, but not with the same springs used for closing.
A stored energy operator consists of three systems: spring
charging dr
i
v
e
,
cam and ratchet assembly, and the four bar
toggle linkage (Figure
4,
A· D). These systems
are
disengaged
·6·
from each other except while performing their specific
functions. For example, the spring charging drive and
cam-ratchet assembly are disengaged except when the cam·
ratchet arrangement is being charged. Similarly, the cam·
ratchet and four bar linkage are free of each other except
during closing.
Stored energy operated breakers normally
require
a
single commercia! relay for control. This relay is furnished
to
match the control voltage.
Reclosing Control (Optional
•
For Reclosing Applications
Only)
The trip latch check system provides the necessary
control to perform the reclosing function when the switch­
gear is equipped with reclosing relays.
The system is comprised of three elements: A mag­
netic actuator, a non-contacting magnetically operated
Hall
effect switch (sensor) and a timer module. The system
performs two distinct functions prior to enabling the
re­
closing operation.
1.
It senses that the trip latch has returned to its reset
position and is
ready to receive a reclosing
operation.
2.
Imposes a delay following latch reset to insure the
linkage assembly has fully reset and then applies power to
the spring release coil.
The
n
o
n
-
c
ontac
t
i
n
g magnetically operated Hall effect
switch and magnet actuator combine to perform proximity
detection of
the
trip latch
tail.
The speed of operation
and life expectancy of this proximity sensor system is not
limited by mechanical actuation as no
physical
contact
between
the
actuating magnet and Hall switch exist. The
switch consists of a Hall sensor,
trigger
and amplifier
integrated on a silicon chip.
Its complete
encapsulation
isolates the device from environmental
e
ff
e
cts
.
AUXILIARY EQUI PM ENT
Auxiliary Switch
Mounted on the breaker, the auxiliary switch is
normaily used to open the trip circuit when the circuit
breaker is opened.
As
this multi-stage switch operates from
the breaker disconnect blades, circuitry dependent on the
breaker, such as indicator lights, etc., is wired through this
switch. The individual stages are easily converted to ''a" or
"b" without disassembling the switch (see Figure 5).
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