Post on 02-Apr-2018
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HK
ABB
03-01
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Low VoltageSwitchboard design
problems in Hong
Kong
Ir C. H. Fung
Tel 29293701
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Normal switchboard design procedures !
n Read the single line diagram / schematic diagram
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Normal switchboard design procedures !
n Check the switch Room size
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n Which supplycompanies will beconnected, HEC or CLP
n Which IDMTcharacteristic will be
installed
n Check the
specifications
Normal switchboard design procedures !
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Normal switchboard design procedures !
n Code of Practice forthe electricity
(wiring) regulations
n Supply rules of theCLP / HKE
n BS, EN or IEC
standards
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Switchboard design : draft preparation
n Put all the switchgears into the
cubicles according to the
schematic diagram
n A switchboard draft finished
n Prepare the busbar routing
according to the schematic
n
Note the form of segregationof the cubicles
n Busbar size, CT chamber,
KWH location, Change Over
switch.
Switchboard Draft before prepare the formal drawings
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Switchboard design: fine tune the design
n Try to put the switchboard into
the switch room
n Clear maintenance access as
specified in the EMSDs COP(Front = 900mm, Rear =
600mm)
n Note the Cable/ Busbar from
the supply comnpanyn Note the supply cos phase
sequence
n Note the CT Chamber size
and 600mm min. 2600mm
max AFFL
C. T. Chamber
Switchboard in factory
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Switchboard design-3
n Note the size of the KWH
meters installation
n Note the incoming cable
routing and reserve enough
space and bending radius for
cable and busbar entry
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Specification-1
n 50KA 3sec for 2500A, 2000A, 1600A, and
1250A busbar and its associated components.
n 50KA 3 sec for 800A and below is impossible
n Type Tested Assembly (TTA) to IEC or BS
standard is hard to comply.n Extension of Busbar at both side of the
assembly in a small switch room is waste of the
material and not feasible
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Specification- Functional units
n Functional Units located between 400mm and
1800mm AFFL is difficult to comply if the switch
room is small
n ACB should be Solenoid operated is for OLD design
ACB. Nowadays, ACBs are motorised
n
Oil Dash-Pots overload protection is applicable tothe ancient ACB or can be found in the Museum
n Double break Isolator is hard to find in the market
n
50KA 1 sec MCCB is impossible to comply
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Specification- IEC 60439-1 Page 1
n 7 Type Tests
n Temperature rise
n Dielectric test
n Short Circuit Test
n Effectiveness of the protective circuit
n Clearance and Creepage distances
n Mechanical Operation
n Degree of Protection
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