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4.5 Interlocks/locks
W ARNING
The operations must be carried out by applying
normal force (not more than 450 N), only using the
special tools. Should they be prevented, do not
force the mechan ical interlocks and check that the
operating sequence is correct.
The
mechanical
locks,
switchgears, are "preventive locks", which prevent a
certain operation from being performed unless the
conditions required for service are observed. In any
case, do not force the mechanical locks and check
that the operating sequence is correct.
Main interlocks fitted are as follows:
1 – Mechanical interlocks:
a) As the three-position disconnector does not have
any making capacity, it can only be operated with the
circuitbreaker open.
b)
Operation
of
the
performed
if
the
selector
disconnector is in the central position.
For ENA version only:
c) The cable test access cover can on ly be opened
with the three-position disconnector in the EARTH
position and the circuit-breaker closed.
d) The voltage transformer cover can only be opened
with
three-position
position and the circuit-breaker closed (interlock by
means of keys).
2 – Key locks (optional)
A. Key free only with the three -position disconnector
switch in the OFF position and the circuit -breaker
open (key A).
B. Key free only with the three -position disconnector
switch in the EARTH position and the circuit -breaker
closed (key B).
Key B is also used to allow access to the VT
compartment (ENA version only).
W ARNING
In order to be certain that earth will not be
inadvertently removed, a padlock must be applied
onto the circuit-breaker opening button.
For Bus-section unit only:
C. The three-position disconnector can be moved to
EARTH position only if the key is engaged.
20
fitted
in
UniGear
circuit -breaker
can
of
the
three -position
disconnector
in
the
(Figure 42)
3 – Padlocks:
Using of padlocks is optional for the following:
a) Circuit-breaker opening
b) Circuit-breaker closing
c) Operation with three -position disconnector (from
ON to OFF and vice versa; from EARTH to OFF and
vice versa)
4 – Padlocks (ENA version):
Using of padlocks is mandatory for the following:
a) Circuit-breaker opening
500R
b) Operation with cable test access cover
Using of padlocks is optional for the following:
c) Circuit-breaker closing
d) Operation with three -position disconnector (from
ON to OFF and vice versa; from EARTH to OFF an d
vice versa)
Note:
It is necessary to use padlocks with 4 - 8 mm hasp
diameter.
only
be
EARTH
F i g u re 42: Key l o cks.
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