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ProductsSK-B Type Compact High-Voltage Bus Duct with 7.2-kV Rating

Conventionally, air-insulation bus ducts comprising bareconductors supported by porcelain or epoxy insulators
were generally used for high-voltage power feeders.
Furukawa Electric also has been manufacturing andmarketing this type of product as a regular lineup under
the name of “K-B type nonsegregated-phase bus duct”
with rated voltage of 3.6 kV~36 kV and rated current of
600 A~3000 A. Recently, however, use of bus ducts aresometimes avoided due to their large footprints inevitably
resulting from their structures. With the recent upgrades in
power demands, moreover, power feeder systems tend to
shift to high-voltage trunk line systems, creating, year byyear, the needs for installation space saving and weight
reduction.
Against this background, we have been successful indeveloping a high-voltage bus duct of reduced footprint.
The developed product comprises newly developed
supporting insulators of three-phase-integrating type on
which the conductors are placed endways.

1.

Enclosure

Figure 1

STANDARD SPECIFICATIONSStandard: In conformity with JEM 1425Installation place: Indoor
Number of phase: Three-phase, three-wire
Rated voltage: 7.2 kV
Rated current:
Aluminum conductor: 400 A~2000 ACopper conductor: 600 A~2500 A
Insulation class: 6-A
Impulse withstand voltage: 60 kVPower-frequency withstand voltage: 22 kV
Material:
Enclosure: Steel
Conductor: Aluminum or copper
Surface treatment:
Enclosure: Melamine or epoxy paintColor: 5Y7/1, 50 % gloss
Contact surface: Tin plated
Insulating material:
Conductor sheath: Heat-resistant PVC
Supporting insulator: Epoxy
Interphase barrier: Polypropylene

Insulating supporter

ConductorPhoto 1

2.

Cross-section.

Appearance of SK-B feeder.

STRUCTURE

The conductors are sheathed by flame-retardant, heatresistant PVC using continuous extrusion, and are placed
endways on epoxy supporting insulators of three-phaseintegrating type, and are accommodated in a steel duct
enclosure. See Figure 1 and Photo 1.

3.

FEATURES

1) Compared with the K-B type nonsegregated-phasebus duct, the new product has been reduced to about
one-third in cross-sectional area and to about 75 %in weight, realizing the most compact and lightest bus
duct in the business quarter. See Figure 2.
2) The epoxy supporting insulators of three-phaseintegrating type has been developed to enable theconductor arrangement with minimal insulation
distance, resulting in downsizing of the bus duct.

Furukawa Review, No. 24

2003

102

SK-B Type Compact High-Voltage Bus Duct with 7.2-kV Rating

Generator
SK-B compact
high-voltage bus duct

Transformer

K-B type

Figure 2

SK-B typeComparison between K-B type and SK-B type.

Interphasebarrier

Figure 4

Details of joint.

Example of bus duct system.

3) The enclosure adopts a plate-assembly structurevirtually eliminating welding and welding flexure, sothat an attractive appearance has been achieved.
4) A cost reduction of about 15 % has been achieved
over the K-B type nonsegregated phase bus duct.
5) The joint has a large inspection opening, permitting
easy maintenance work such as additional fasteningof bolts.
6) Dimensional adjustment of ±3 mm is allowed per
one joint, enabling accommodation of architecturaldimensional errors.
7) The interphase barrier to be installed on theexposed conductors at joints is designed to have sucha structure that the barrier is inserted in the grooves
on the epoxy supporting insulators, enabling easy
installation. See Figure 3.

4.

Figure 3

H-P low-voltage
bus duct

Distribution board

APPLICATION EXAMPLE

Using miscellaneous parts such as elbow, the SK-B bus
duct can be configured to adapt to any equipment layoutthat is given. Moreover, combination with low-voltage
bus ducts results in reduced footprint of the entire feedersystem, ensuring open space indoors. Thus, a smart
feeder system can be proposed using this product.
For more information, please contact:
Electric Feeder Dept., Industrial Machinery andMaterials Div.
TEL: +81-463-24-8365
FAX: +81-463-24-8367

Furukawa Review, No. 242003103