Siemens RL Instruction Manual page 6

Fuse Carriage
ment is indicated by movement of its reset handle to a
horizontal position.
The breaker-mounted open-fuse trip attachment holds the
circuit breaker in its tripped position, and the circuit breaker
cannot be reclosed until the open-fuse trip attachment is reset
manually. The trigger fuses should also be replaced when
replacing the main power fuses if open-phase indication is
desired. The system will function normally if the trigger fuses
are not replaced. However, phase indication will not be
provided.
Use only Chase-Shawmut Type Tl-600 trigger fuses in the
indicator.
Key Interlock Syste m (See Figures
Each fuse carriage is equipped with an integral key-operated
interlock for a particular cubicle location. Interlocks prevent
racking the fuse carriage in or out of the connected position
if its associated circuit breaker is not in its locked open
position.
Once the circuit breaker is open the key can be rotated,
lowering the locking bar to prevent closing the circuit breaker.
The key can then be removed from the circuit breaker lock
and transferred to the lock on the fuse carriage. The fuse
c a r r i a ge lock operates the slide interlock cover over the
racking screw of the fuse carriage. Once the racking screw
is exposed. the fuse carriage can be racked in or out using
the racking handle. The key is retained in the lock when the
fuse carriage is between the TEST and CONNECTED positions.
Key !nter!ock Mounted in
Figure 12.
Com;Jartment
12 13)
and
Circuit Breaker
T esting Open Fuse Trip Attachment
The open fuse trip attachment is operated by the voltage
developed across the open fuse. This voltage is applied to a
transformer and rectifier combination. The output of the rec­
tifier is connected to the coil of the trip attachment on the
circuit breaker through the secondary disconnects of the two
devices. For testing, voltage is applied to the input of the
transformers. To do this. the fuses must be open. or the
transformer disconnected from the fuse. Otherwise, the fuse
will short out the test source. For safety, the following proce­
dure is recommended.
A
1 Hazardous voltage.
1 Can cause death, severe personal injury,
el e ctrical s ho c k bu r n s or property
damage.
!
Line voltage may be present inside trigger
fuse assembly. Do not remove trigger fuse
cover when circuit breaker is in CONNECT
osition.
1.
Open the circuit breaker and rack it to its TEST position.
Open the circuit breaker compartment door. remove the
key from the interlock.
2. Use the key to unlock the fuse carriage racking
mechanism. Rack the fuse carriage to its TEST position.
At this point. the main disconnects are clear of the power
circuit. while the secondary disconnects are still
engaged. The key can now be rotated and removed from
the fuse carriage racking mechanism lock.
Fuse Carriage Key Interlock
13.
Figur e
WARNING
21
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