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48
U N I G E A R Z S 2 I N S TA L L AT I O N , O P E R AT I O N A N D M A I N TA I N A N C E I N S T R U C T I O N M A N U A L
Fixed voltage transformer in cable compartment
CAUTION!
The cables compartment with bolted cover
shall be opened only by authorized maintenance
personnel. For replacement of primary fuses,
please refer the electrical data and article number
—
Figure 70 - VT in Cable
—
Figure 71 - VT connection (disconnected) position
8.4 Service trucks
It is possible to use service trucks for earthing the
cable and busbar side circuits.
—
Figure 72 - Earthing Truck without making capacity
Before accessing potential
transformers in cable compartment
the circuit shall be earthed.
—
Figure 73 - Earthing truck with making capacity
8.4.1 Earthing truck without making capacity
These trucks carry out the same function as the
earthing switches without 'making capacity'.
Therefore they do not have the capacity to earth
the live circuits. They are used to ensure fixed
additional earthing, as required by the plant
service and maintenance procedures, as at further
guarantee for personnel. The use of these trucks
foresees removal of the circuit breaker from the
switchgear, and its replacement with the truck.
The earthing trucks are fitted with an interlock
which, when activated, prevents their rack-in
during the presence of live voltage on the busbar
or cable section
These trucks are available as two versions:
•
Main busbar system earthing
•
Power cable earthing
During the rack-in process, the main busbar
earthing truck operates only the top shutter and
earths the busbar contacts with switchgear
earthing. Whereas, the power cable earthing
truck, during the rack-in process operates only the
bottom shutter and earths the power cable
contacts with switchgear earthing. These trucks
can also be used in the bus tie units. Wherein,
both sides of the busbar system can be earthed
by using both the types of trucks one after
another.
CAUTION!
Do not put this earthing truck to a live
circuit. Always ensure the circuit is in
OFF condition before putting earthing
truck. Ensure auxiliary supply is ON
before putting earthing truck in to test
condition. Ensure that the VDI/PT shall
be in good condition before inserting
the earthing truck into switchgear.
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