7
4.2
Bolting Torque Values
BreakMaster Load Interrupter switches are furnished with medium carbon steel hardware having a high tensile
strength of 120,000 psi. SAE 5 or better hardware should be used for any additional bolting. The use of a torque
wrench is recommended to assure the following torques. These torques apply to aluminum or copper
connections. When torquing bolts the following values are nominal:
1
⁄
4
” bolts – 4 lb. ft.
5
⁄
16
” bolts – 9 lb. ft.
3
⁄
8
” bolts – 16 lb. ft.
1
⁄
2
” bolts – 39 lb. ft.
5
⁄
8
” bolts – 80 lb. ft.
Flat washers and lock washers should be used for all connections. Washers should not be included under the
heads of carriage bolts.
4.3
Electrical Clearances
The following minimum clearances should be maintained after field modifications:
2.4 kV - 5kV
7.2 kV - 15kV
Between live parts of adjacent phases:
Through air:
3
1
⁄
2
”
5
3
⁄
4
”
Over Surface:
3
1
⁄
2
”
5
3
⁄
4
”
Between live parts and grounded
metal through air over surface:
3
1
⁄
2
”
5
3
⁄
4
”
4.4
Grounding
The ground bus is bolted to the uprights of the frame structure. It is arranged so that connections to
the station ground can be made in any unit. A ground bus is included in each section for connecting the
BreakMaster equipment to the station ground.
4.5
Medium Voltage Electrical Connections
4.5.1
Connection by Cable Supplied with BreakMaster Switch
a. Cables are not factory pre-cut to proper length. Installer must cut to fit.
b. Since factory cables are unshielded, they must be properly separated from each other, from all grounded
metal parts, and from transformer bushing/terminals of other phases.
c. BreakMaster conforms to ANSI standards concerning phasing. Phases are arranged A, B, C, front to rear,
top to bottom, and left to right at connection points unless otherwise noted on the drawings. The installer
is responsible for maintaining continuity of phasing throughout the system.
d. Lugs are provided with the switchgear for terminating cable to the transformer bushings/terminals.
4.5.2
Connection by Bus Bar
a. Flexible bus straps or splice plates and hardware are furnished with the BreakMaster Load
Interrupter Switch.
b. Copper bus bar is tin or silver plated.
WARNING
It is very important that the equipment be adequately grounded to insure that all
parts of the equipment, other than live parts, need to be at ground potential.
!
BreakMaster Load Interrupter Switch
