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Vehicle Description
Vehicle Function and Operational Interlocks
Type FSV vacuum circuit breakers are comprised of the
interrupter/operator module fitted to a vehicle. This inter-
rupter/operator module is an integral arrangement of op-
erating mechanism, dielectric system, vacuum interrupt-
ers, and means of connecting the primary circuit. The ve-
hicle supports the interrupter/operator module, providing
mobility and fully coordinated application in Siemens type
"F" switchgear.
This manual should be used jointly with the Circuit Breaker
Operator manual, SGIM-9918 (3AH) or SGIM-3398 (3AF)
(3AF for 3000A circuit breakers).
Alignment
All aspects of the circuit breaker structure which impact
alignment and interchangeability are checked at the fac-
tory. Field adjustment will not normally be required, but
variations in existing switchgear may require field adjust-
ment.
Hazardous voltages and high-speed
moving parts. Will cause death, serious
injury, and property damage.
De-energize before working on this equip-
ment.
Do not by-pass interlocks or otherwise make
interlocks inoperative.
Elements of the vehicle structure, which are assembled
under fixture control and then are secured and pinned in
place, include the following (no adjustments are required):
• Side channels which provide support to the interrupter/
operator sub-assembly are fixtured square (90) to the
wheel axle holes in the vehicles base.
• The primary circuit conductors are fixtured to appropri-
ate elevation, phase spacing and alignment to the in-
side surface of the guide bar. The guide bar, is set in
the fixture firmly secured and then pinned in place.
• Secondary disconnects are fixtured and pinned in place.
• Shutter cam which raises and lowers protective primary
bushing barriers, is fixtured firmly secured and pinned.
• Circuit breaker grounding contacts, are aligned and se-
curely bolted in place.
• Closing spring discharge roller is located and secured.
• The hinged protective barrier is aligned, adjusted verti-
cally and then pinned in place.
Thus, all those features which must align with elements
of the switchgear "draw out" enclosure, are precisely set,
firmly secured and pinned while the complete circuit
breaker is located in a rigid fixture.
Recommended Tools
• Racking Crank: Original circuit breaker racking crank may
be used.
Interlocks
Inoperative or by-passed interlocks will
cause death, serious personal injury and
property damage.
Mechanical and electrical interlocks are
provided as integral components of this
equipment to ensure safe use. Interlocks
must be in operation at all times. Read this
instruction manual. Know and understand
correct interlock function. Check interlock
function prior to inserting circuit breaker into
switchgear cubicle.
Circuit Breaker Racking Interlock (Lever Type)
Reference: Figure 1
The racking interlock functions to block movement of the
circuit breaker from the connected or test positions when-
ever the circuit breaker is closed, and to maintain the cir-
cuit breakers mechanism in a "trip free" state whenever
the circuit breaker is "released".
• The circuit breaker is closed whenever the primary cir-
cuit is completed through the vacuum interrupter con-
tacts. This closed condition is caused by rotation of the
circuit breaker shaft, to the position shown in Figure 1.
• The circuit breaker is released (free to rack) when the
plunger shown in Figure 1 is elevated sufficiently to clear
the slot in the cubicle rail.
Function of the closed circuit breaker racking release is ini-
tiated by elevating the racking release handle. This action
causes the interlock bell crank (1) to attempt CCW rotation.
If the circuit breaker were closed, the bell crank will rotate
incrementally causing the "push rod" (2) to rise through
the action of the bell crank (1) and the link (3). This action
will be immediately blocked, because the push rod (2) is
blocked by the circuit breaker shaft mounted interlock le-
ver (4). With motion blocked after this short movement, it
is not possible to raise the plunger above the cubicle rail.
Thus, The Circuit Breaker Can Not Be Released For Rack-
ing When The Primary Contacts Are Closed.
If the circuit breakers primary contacts were open, the cir-
cuit breaker shaft interlock lever will have rotated allow-
ing the push rod (2) to rise freely.
As the push rod rises, its "mushroom" headed append-
age, within the circuit breakers mechanism enclosure,
causes the "interlock" levers to rotate, elevating the "trip
free push rod and cam". This cam encounters the "trip
latch lever", and after typically 8 to 12mm (0.3 to 0.5 inches)
of motion forces the mechanism, through the "trip latch
lever", to the "trip free" state shown in Figure 2.
4
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