vents them from danger and ensure operators in a safe condition all the time.
3.3 Compartment
3.3.1 Circuit Breaker Compartment
(Figure 3/2 , 3/3)
The circuit breaker compartment is fitted with the necessary guide rails to accommodate the withdrawable
part,which can be moved betw een the service position and the test/disconnetct ed position.
If the withdrawable part is moved from the service position into the test/disconnected position, the fixed
contacts located in the connection block in busbar compartment C and cable compartment D are automati -
cally covered by metal plates which will be interloc ked mechanically or can be locked by a padlock when the
withdrawable part is moved away. In the test/disconnected position, the withdrawable part is still completely
inside the panel with the door closed. The switching operations (including manual operation) are carried out
with th e doors closed.
3.3.2 Withdrawable Part
(Figure 3/4 , 3/5)
The manually moved withdrawable part consists of a robust sheet steel structure on which the circuit breaker
poles are mounted and the breaker mechanism with relevant compo nents is installed.
Contact arms with spring-loaded contact systems are fitted to the circuit-breaker poles.These create the electri
cal connection to the switchgear when the withdrawable part is inserted into the service position. Detailed
information on the vacuum circuit breaker can be found in the corresponding instruction manual.
The signalling, protection and control wiring between the switchgear and the withdrawable part is coupled by a
multiple pin control wiring plug.
As soon as withdrawable part has been slid into the switchgear and its interlock yoke has engaged in the test /
disconnected position, it is positively connected to the switchgear panel. At the same time, it is earthed by
earthing contacts and earthing rail. The position of withdrawabl e part can be checked on the electrical positio n
indicator or through the sight glass in the door at any time. The stored -energy spring mechanism of the circuit
breaker including controls and indicators is accessible at the front of the withdrawable part. Apart from the
version with a fitted circuit breaker, withdrawable parts with other equipment such as voltage transforme r, are
available.
3.3.3 Busbar Compartment
Busbars are laid in sections from panel to panel,and are held in place by the tee-off conductors and by busbar
bushings. The conductor mat erial used is tubing with a D-shaped cross section, in eith er singl e or doubl e
configuration depending on the current rating. The connection to the flat tee-off conductor s is made withou t
any special connecting clamps. The busbars and tee-off conductors are covered with shrink-on sleeves. The
bolt connections in the busbar system are normally covered by insulating covers. In conjunction with bushings ,
panel by panel partiti oning is realised .
The main busbar can be fitt ed with either single and double form or aluminium rectangle type according to the
client s requirements.
3.3.4 Cable Compartment
(Figure 3/6)
Current transform ers and an earthing switch (with manual operating mechanisms) are located here.Installatio n
of surge arrestor is possibl e. Multipl e parallel pow er cables can also be available without difficulty. The cable
sealing ends can be fitted in particularly favourable conditions. A removeable plate for cable glands is located in
the cable entry area.
Installation of voltage transformers at cable side of the panel is in preparation and will have influence on the
depth of the panel.
The earthing switch is designed with a making capacity of 62.5 kA (design for 80 kA in preparation).
3.3.5 Low Voltage Compartment
(Figure 3/7)
The low voltag e compartm ent, tog ether with its front door, accommodat es the secondary equipment of the
switchgear panel required for the particular application.
The control wiring in the switchgear panel area is led through generously dimensioned and metal covered
ducts. The left hand duct is reserved for the incoming and outgoing control wires, and the internal wiring in the
panel is located on the right hand side.
At the top of the left hand duct, an entry for control cables is reserved with the free-cut rubber sealing which will
keep the protection class IP4X for the whole encloser of the switchgear panel.
3.4 Interlocks/Protection Against Maloperation
A series of interlocks are provided to prevent fundam entally hazardous situations and mal-operation,thus pro
tecting both personnel and the switchgear itself. The interlocks which are normally individually effective are as
follows:
The withdrawable circuit brea ker can only be moved from the test/disconnected position into the service
position (and back) with the circuit breaker open and the earthing switch open (Mechanical interlock).
The circuit breaker can only be closed when the withdrawable circuit breaker is precisely in the defined test
position or service position (Mechanical interlock).
The circuit breaker can only be opened manually in the service or test position when no control voltage is
applied, and can not be closed (Electromechanical interlock).
The circuit breaker can be only closed when withdrawable circuit breaker is in the test/disconnected position
or removable position (Mechanical interlock).
Earthing switch can only be closed when the withdrawable circuit breaker is in the test/disconnected position
or the removed position (Mechanical interlock).
The withdrawable circuit breaker cannot be moved from the test/disc onnected position into the service posi-
tion when the earthing switch is closed (Mechanical interlock).
The circuit breaker control cable plug be locked when withdrawable circuit breaker is in the service position.
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