Panel Design And Equipment; Basic Structure And Variants; Enclosure And Partitioning - ABB UniGear ZS1 Instruction Manual

3. Panel design and equipment

3.1 Basic structure and variants

3.2 Enclosure and partitioning (Figure 2)
The basis for the UniGear ZS1 panel is the incoming/outgoing feeder panel with SF6 ¹) or vacuum
circuit breaker using insertion technology. It is divided into busbar compartment, circuit-breaker
compartment, cable compartment and control cabinet for the secondary equipment. Apart from this,
there are variants for all operating needs.
For busbar isolation, two panels are necessary, the coupling panel with the withdrawable circuit-
breaker part and a bus riser panel (optional with busbar metering and earthing). In equipment without
busbar isolation, a direct bar connection between the busbars will be established.
The UniGear ZS1 switchgear includes also the variant of incoming/outgoing panel with the switch-
disconnector NAL-F with the stationary mounting of switch-disconnector. The panel is divided into
busbar compartment, switch-disconnector compartment including cables and control cabinet for the
secondary equipment.
The UniGear ZS1 panels can also be set up in two rows; back to back fixed together in so-called duplex
arrangement with a double busbar system.
Further details about installation and switchgear equipment can be obtained from the documents of
relevant order.
¹) For series 550 only vacuum breaker is available.
The enclosure and internal partitions of the panels are of 2 mm thick high quality galvanised steel
sheets.
The three high voltage compartments (busbar compartment, circuit-breaker compartment and cable
connection compartment) are equipped with top-mounted and secured pressure relief flaps.
These open in the case of overpressure due to an internal arc fault.
The front of the panel is closed off by pressure resistant doors which open to an angle of 130°.
Cable and circuit-breaker compartments have their own doors.
The circuit-breaker compartments can be equipped with inspection windows made of security glass.
Neighbouring panels are partitioned from one another by the side walls of each panel and, as a result
of the design, the air cushion remains between these walls when the panels are jointed together.
The enclosure is completed above by top-mounted pressure-relief flaps which, according to the rated
branch conductor current, are made of sheet steel or expanded metal and below by means of floor
covering 17, made of sheet metal which cannot be magnetized.
The pressure-relief flaps are secured with steel screws on one longitudinal side and on the other
longitudinal side with plastic screws.
In the case of internal overpressure, the plastic screws are the point of rupture.
Arc fault current limitation can be achieved by undelayed circuit-breaker release, carried out by
auxiliary switches operated by the pressure wave.
The switchgear can be equipped with the following systems:
• Ith limiter: the auxiliary switches 11.5 (figure 28) are operated by the pressure relief flaps. For units
over 25 kA (see chapter 3-7);
• Fast recovery device: the auxiliary switches are mounted on the pressure sensors and operated by
the sensor stroke pin (see chapter 3.6).
The necessary safety measures to counteract the effects of an internal arc fault must be ensured in
relation to the ceiling height. In individual cases, this may require additional operator protection
measures on the switchgear panels.
These measures include:
1. Mounting a pressure relief duct 50 on the top of the switchgear, with further channels leading out
of the switchgear room in a form appropriate for the design of the building. The shock wave and
arc discharge are channelled off in ducts (see chapter 5.8);
2. Mounting a pressure relief duct with blow-out apertures located above the duct at the ends of the
switchgear and pointing towards the centre of the switchgear (diverter duct). The shock wave and
arc discharge then emerge in an extremely attenuated form and in a location which is not critical
for the operating personnel.
The rear wall of the busbars of busbar compartment 84, intermediate wall 9, mounting plate 12 with
shutters 12.1/12.2 and horizontal partition 20, form part of the internal partitioning.
The internal metallic partitioning makes safe access to the circuit-breaker and cable compartments
possible even when the busbars are live.
The low voltage compartment for the secondary equipment is completely protected from the high
voltage area thanks to its steel-sheet casing.
On the end sides, cover plates ensure good appearance and are mechanically and thermally arc fault
proof should such an event occur in the end panel.
Doors and rear walls as well as the cover plates are thoroughly cleaned and treated against corrosion
before receiving a high quality double coating of paint.
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