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3.5 Interlockings
3.5.1 Interlocking principle
Purpose
Interlockings
3.5.2 Interlockings of the fixed type switchgear
3.5.2.1 Interlocking unit
General
Positions
Earthing switches
ABB
Uniswitc h Operation and
Maintenanc e Manual
The purpose of the interlocking devices is to prevent incorrect operation
of the switch-disconnector and earthing switch and thereby to ensure
personnel safety. The interlocking is in operation even if the doors to the
cable and control compartments are open.
Interlocking includes:
•
Normal interlocking which is fitted as standard in every cubicle.
•
Additional interlocking devices which are optional and to be chosen
by the customer.
Permitted control operations of the Uniswitch switchgear and the three-
position SFG switch-disconnector are defined by the position of the
selector of the interlocking mechanism.
The interlocking selector has four positions:
Position 1: Operation
SFG switch-disconnector can only be operated close-open. The cable
compartment door cannot be opened.
Position 2: Padlock
SFG
switch-disconnector
compartment door cannot be opened.
Position 3: Test and earthing
SFG switch-disconnector can only be operated open-earthed. The cable
compartment door cannot be opened.
The interlocking applies also to the earthing switches EF and EM, which
are used for earthing the bottom of the fuses and current transformers.
These switches are mechanically connected to the operating device of
SFG switch-disconnector and they are operating simultaneously with the
SFG when it is operated between open and earthed position.
Position 4: Door open
The SFG switch-disconnector is in the earthed position and cannot be
operated. The cable compartment door can only be opened if the
switch-disconnector is in the earthed position and the interlocking device
is in the 'Door open' position.
Refer to 3.5.2.2 Normal interlocking.
cannot
be
operated
and
the
cable
15
UNI S14GB 05-02
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