STANDARDS
Cable duct systems are designed to meet the
following standards:
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C.S.A. C22.2 No. 27: Busways
-
C.S.A. C22.2 No. 201: Metal
Enclosed High Voltage Busways:
-
CSA C22.2 No. 0-M1982: General
requirement - Canadian Electrical code
0.4-M1982 - Bonding and grounding of electrical equipment
27-1973 - Bonding
- A.N.S.I. C37.20 a,b,c & d. (I.E.E.E. Std. No. 27):
Switchgear Assemblies Including Metal Enclosed Bus.
-
N.E.M.A. WC7 (I.C.E.A. Stds. Publication
No. S-66-524) Cross-Linked-Thermosetting-Polyethylene Insulated
Wire and Cable for the Transmission and Distribution of Electrical Energy.
-
N.E.M.A. WC8 (I.C.E.A. Stds. Publication
No. S-68-516) Ethylene-Propylene-Rubber Insulated Wire and Cable
for the Transmission and Distribution of Electrical Energy.
-
UL-1072 Standard for Medium
Voltage Solid Dielectric Cable.
PRODUCTS
General Switchgear & Controls Ltd. manufactures
assembled or field loaded cable duct systems and necessary fittings rated
6,000A maximum, 15KVAC maximum, 2kV DC maximum, single phase or 3 phase,
600V, 3 wire 5kV, 15kV with or without neutral using insulated copper or
aluminum cables.
The cable duct enclosure may be ventilated or
totally enclosed, designed for indoor or outdoor application, maximum
distance between supports 12 Feet inside (3.65M), 10 Feet outside (3M). The
cable duct may be installed horizontally or vertically.
DESCRIPTION
The bus duct enclosures are made of fabricated
aluminium enclosure loaded with insulated cables supported and segregated by
insulated cable support assemblies fastened to the enclosure at suitable
intervals. Each straight length and necessary fitting is fully fitted at the
factory. The factory assembled parts are installed in the field in
accordance with the manufacturers instructions and hardware provided.
CONSTRUCTION
The two side walls are the main structural members
and are made of extruded aluminium 0.08 inch to 0.125 inch (2-3mm) thick
dependant on duct enclosure height. The top and bottom covers are made from
aluminium sheet 0.08 inch (2mm) thick. The covers are joined by an overlap
joint. Cable support systems and channels are provided at 36 inch (915mm)
intervals or less. The vertical channel for cable supports are placed on the
top of the lower horizontal channel and against the vertical side wall.
CABLE SUPPORTS
The cable supports are made from glass reinforced
polyester, moulded with two sets of three or six cable grooves, one set on
each of the two opposite sides. Each cable support has one through hole
approx. 7/16 inch (1mm) diameter.
The cable supports are placed in the supporting
channels in pairs. The alternate layer of cable and cable supports are
installed with the cable support alternated in direction with the grooves
facing each other. The grooves are specially designed (smaller than the semi
circles), so that the cables are clamped before the two supports touch. The
cable is thus positively clamped by the clamping channel placed on the top
block.
This top channel is bolted through the side wall
and the block channel support in the cable that can be clamped is 1 inch
(25mm) minimum and 2 inch (650mm) maximum.
COVER
The top cover is louvered aluminium sheet of 0.08
inch (2mm) thick approx. 36 inch (915mm) in length and joined by an overlap.
The top covers are fixed to the flange of the vertical walls using stainless
steel screws.
BENDS, CORNERS AND FLANGES
Flange is constructed from 3/16 inch (5mm)
aluminium sheet and sized to suit the cable duct enclosure. Adjacent to this
flange a weather seal plate in which aluminium tubes welded in place to
match the cable layout pattern of the cable duct, sealing is ensured by heat
shrinking of 8 inch (20mm) long tube between the aluminium tube in the
flange and cables in the cable bus duct.
Whenever the cable bus duct passes through walls
or ceiling an internal fire barrier (1/2 hour rated) is provided as per CE
Code Part 1. Special barriers up to 3 hours can be provided. For vertical
run cable bus duct, drainage holes are provided.
CABLE JOINTS AND SPLICES
Factory or field joints are made as follows:
CABLE JOINT INSULATION
5KV AND BELOW (INDOOR)
High density polyethylene tube 0.125 inch (3mm) thick
approx. 30 inch (762mm) length is used over the joints and is held in
position by cable support assemblies on each side of the joint.
5KV AND HIGHER (ALL OUTDOOR)
Raychem heat shrink insulation kits or equivalent as
described in manufacturer's literature are used.
GROUND BONDING
Each section of the cable bus enclosure is bonded by
the bolted joint between sections. Bolted are secured by external toothed
plated lock washers which bite into the side walls.
Each expansion joints is jumpered by a 18 inch
(457mm) length of cable on each side of the duct and size of the cable
selected in accordance to CE Part 1 table 16. The cable is terminated using
compression type lugs and fixed on each side of the cable bus ducts using
3/8-16 inch bolts and external toothed lock washers.
CABLE
Power cables of size, type, insulation and quantity
per phase will be used as shown in the manufacturers catalog. CSA approved
cables will be used
MARKING
On each finished lengths of cable bus enclosure a
Nameplate containing the manufacturer's name, type, current rating of phase
and neutral cable where applicable, BIL rating where applicable) and maximum
distance between supports 12 Feet indoor, 10 Feet outdoor is provided.
Complete instructions for making field joints is
shipped with each termination kit.
FACTORY TESTS
Each completed length of cable duct including
fittings is tested as follows:
-
Dielectric test based on CSA C22.2 No. 201-M1984
for system voltage 751V to 38kV for system.
-
Voltage between 751V, test voltage to be 24kV DC
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