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7.2 Three-position disconnector operation
The “off-load” three-position disconnector is manually
operated by means of a manual mechanism.
A firm action is required to overcome the resistance
as the blades make contact.
If excessive resistance is experienced, stop and make
sure that the operation is correct.
An interlocked selector mechanism (Figure 90)
prevents the following: three-position disconnector
movement with the circuit-breaker closed, circuit-
breaker closing whilst the selector is in use and three-
position disconnector moving directly from ON to
EARTH positions (and vice versa).
Unless the three-position disconnector is fully in the
EARTH, OFF or ON position, circuit-breaker closing
and removal of the three-position disconnector
operating lever is mechanically limited.
The fully end position of three-position disconnector in
ON, OFF or EARTH position is achieved by final
position of operating handle in the front cover
operation slot. The operating handle after finishing the
movement should almost touch the upper or bottom
edge of operating slot (Figure 91) - variants A and C.
Not correct position of operating handle is indicated in
(Figure 91) - variants B and D.
The fully end positions of three-position disconnector
are also indicated by status indicator on the front
cover (Figure 35). To prevent dangerous or
inadvertent operations, it is possible to lock the
selector mechanism by means of two padlocks (Figure
90): one in the position OFF-EARTH of the three-
position disconnector, and the other in the position
OFF-ON of the three-position disconnector.
WARNING
The removing of operation handle before reaching
fully end position is not allowed otherwise the
functionality of interlock mechanism can be
damaged.
Figure 90: Three-position disconnector
1 Interlocked selector mechanism
2 Padlock
Figure 91: Position of operating handle.
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