Plunger Position Mechanical Interlock; Automatic Closing Spring Release - Siemens 5-FSV-350 Installation Operation & Maintenance

Vehicle
Description
The breaker is closed whenever the p rimary circ u it is com­
•
pleted through the vacuum interrupter contacts. This closed
condition is caused by rotation of the breaker shaft, 63 to the
position shown in figure 24b.
The breaker is released (free to rack) when the plunger shown
•
in figure 24a is elevated sufficiently to clear the slot in the
cubicle rail .
Function o f t h e closed b reaker racking release i s initiated by
elevating the racking release handle. This action causes the
interlock bell c rank, 1, to rotate CCW The bell c rank will rotate
causing the "push rod ", 2, to rise thru the action of c rank, 1 ,
a n d l i n k , 3 .
A s t h e p u s h rod rises , i t s "mushroom" headed appendage,
within the breakers mechan ism enclosure, causes the " inter­
lock" levers to rotate, elevating the "trip free push rod and cam·:
This cam encounters the "trip latch lever", and after typically 8
to 1 2mm (0.3 to 0 . 5 inches) of motion forces the mechanism,
thru the "trip latch lever", and coupled "trip latch" to an opened
and "trip free" cond ition.
Continued full CCW rotation of the interlock bell crank causes
the pl unger to clear the cubicle rail allowing the "open trip free
breaker" to be moved from the connected position .
The lower interlock bell c rank is ret u rned to the plunger en­
gaged position, fu l ly c lockwise, by the action of double torsion
springs at each end of the bell c rank. It i s stopped and main­
tained in the position which ensu res full plunger engagement
by a spring pin of sufficient length at the top of the pl unger
which straddles the g u ide bar and g u iding channel .
The breaker may be pad locked in an "open tri p-free" state.
Provision
has been made for loop i ng a padlock t h rough the
" racking release handle" and a stationary cover mounted an­
gle. The position of the racking release handle at the point of
padlock hole alig nment ensures the breaker is t ri p-free yet the
plunger engages the rail preventing b reaker movement.
Plunger Position Mechanical
Interlock
In order to prevent the motor charging c i rcuit from " making
and breaking" as the b reaker and cubicle secondaries make
or break physical contact, an electrical switch is p rovided . This
switch i s mounted within the connection box, and is ope rated
by a lever attached to a member on the interlock bell c rank.
The switch is adjusted to ensu re the breakers charging circuit
is made u p before the racking plunger achieves full engage­
ment. Typically, the plunger will be 51 mm (2 inches) off the
floor when this switch makes the circuit.

Automatic Closing Spring Release

Reference Figures 24a, 25a and 24b
The automatic closing spring release featu re is provided to
ensure all spring energy has been discharged i n the mecha­
nism p rior to the breakers removal from the cub1cle. The open­
ing springs are d ischarged prior to the breakers release for
racking , and since automatic closing spring discharge occurs
while the breaker IS trip free and 1ts charging circuit is opened.
we can be assu red all spnng energy has been released as the
breaker exits the c u bicle.
Reference to Figure 25b reveals the essential elements of this
system . As the breaker exits the cubicle, the roller encounters
an actuating angle in the floor of the cubicle. As the roller strikes
the angle it must rise, and this change in elevation is ampl ified
thru a lever and fulcrum arrangement located above the roller.
Movement of the roller from a typical free height of 65mm (2 56
inches) to 74mm (2 91 i nches) must produce approximately
20mm (075 inches) of vertical motion at the "spring dump tube"
Reference to Figure 24b shows the spring d u m p tube tele­
scoping the trip free push rod . and thus, the spring dump tube
i s able to move against the mechanisms interlock levers inde­
pendently of the trip free function. As the dump roller ap­
proaches the actuating angle the trip free rod will be elevated ,
holding the mechanism trip free. When the rol ler strikes the
actuating angle, it overtakes the trip free push rod and moves
beyond the trip free position. This action is allowed because
the "mushroom " tip at the top of the trip push rod is not at­
tached to this push rod , but simply "floats" above it, captured
by the mechanisms interlocking levers.
T h e s p r i n g d u m p t u b e n o w m o r e ful l y e l evates the
nisms trip push rod cam and closing spring release cam (each
attached to the same push rod). The spring release cam con­
tacts and d i splaces the close latch lever causing release of
the closing springs into a t r i p free mechan ism. Thus all spring
energy is d ischarged as the breaker leaves the cubicle.
The spring dump roller must now overtravel the structu ral ac­
tuating angle, and not be al lowed any fu rther elevation. The
spring dump push rod accommodates this overtravel by em­
ploying a number of collars and bellvi lle washers. The u pper
most collar is fixed and provides a defin ite stop after approxi­
mately 22mm (0.88 inches) displacement. The additional mo­
tion of rollers and levers required to complete overtravel is
allowed by compression of the bellville washers. The collar
i mmediately above the bellville washers is fixed, and the one
below free to slide.
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