4.3 Interlock/ protection against incorrect
operation
4.3.1 Panel internal interlocking (4/12)
To prevent hazardous situations and erroneous
operation, there is a series of interlocks to protect
both personnel and equipment.
•
The withdrawable part can only be moved
from the test/disconnected position (and
back) when the contactor and earthing switch
are off (i.e. the switch must be off beforehand).
In the intermediate position, the contactor is
mechanically and electrically interlocked and
the earthing switch is mechanically interlocked
•
The contactor can only be switched on when
the withdrawable part is in the ISOLATED or
SERVICE position. In the intermediate position,
the contactor is mechanically and electrically
interlocked
•
The contactor cannot be switched on if an HV
fuse has ruptured
•
In panels with digital control technology,
prevention of malfunction of the apparatus
can also be achieved by means of the panel
software
A
B
C
D
Busbar compartment
Vacuum contactor compartment
Cable compartment
Low voltage compartment
Enclosure
Pressure relief flap
Pressure relief flap
Branch conductor
Busbar
Earthing switch
Current transformers
Voltage transformer
Removable partition
Control wiring
plug connector
Mounting plate
Top shutter
Lower shutter
Withdrawable part
Earthing switch
operating
mechanism
Gland plate
Main earthing bar
Ventilation grid
Emergency
opening
pushbutton
Cable tags
A
B
C
D
•
In the SERVICE or ISOLATED positions, the
mechanically latched contactor can only be
switched off manually when no control voltage
is applied
•
The earthing switch can only be switched on if
the withdrawable part is in the ISOLATED
position or outside of the panel (mechanical
interlock)
•
If the earthing switch is on, the withdrawable
part cannot be moved from the ISOLATED
position to the SERVICE position (mechanical
interlock)
•
Details of other possible interlocks, e.g. in
connection with a locking magnet on the
withdrawable part and/or earthing switch
drive, can be obtained from the relevant
order documents
•
The voltage transformer secondary winding,
when fitted, is isolated when the withdrawable
fused contactor is moved from the SERVICE
position
P A N E L D E S I G N A N D E Q U I P M E N T
15
—
4/12 Example of
UniGear ZVC feeder
unit
—
4/12