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Opening the earthing switch
Ensure that the circuit breaker is in test or
withdrawn position. The crank entrance is open.
Insert the operating lever. This is not possible if
the Earth switch is key locked at closed position.
Turn the lever anti-clockwise 180º to open the
earthing switch. This is not possible if electrical
interlocking coil is on. Do not force.
Withdraw the operating lever.
Close the crank entrance by turning handle
90º clockwise.
(Note: The crank entrance must be closed before
the circuit breaker can be racked into service
position)
See the open (O) position indicator from the lower
inspection window.
Key-lock if necessary the Earth switch in open
position Key-lock if necessary the CB against
racking into service position
8.3.4 Withdrawable measuring parts
Handling of the withdrawable measurement truck
(without the switching operations and
interlocking functions) in the metering switchgear
is as described in section 3.2.3.2.
Withdrawable measurement trucks in incoming
and outgoing feeder switchgears are put into the
cable compartment using ramps. They would
reach their service position immediately on
putting the trucks into the switchgear.
The potential transformer is of shrouded type
with HRC fuses.
Withdrawable measurement trucks in bus riser
and metering switchgears are racked in /out
behind closed door, similar to the circuit breaker
being racked in/out in feeder and coupler
switchgears.
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Figure 65 - Position indicator and auxiliary contacts
—
Figure 66 - Electromagnetic interlock for earthing switch
—
Figure 67 - VT in SERVICE (connected) position
—
Figure 68 - VT in TEST (disconnected) position
—
Figure 69 - VT withdrawn (removed) position view of Contact
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