phase-over-phase GOABSŪ switches are designed for maintenance-free operation
in severe environmental and operating conditions. The switch
components are heavy-duty and rugged in their design, yet the operating
effort to open and close the switch is minimal, even at higher voltages; no
slamming is ever required.
For ultimate reliability, SEECO
phase-over-phase switches utilize a unique construction of the current
carrying components and an over-toggle adjustment (figure 1) in the control
mechanism. This combination of design features and adjustment
procedure insures that the switch stays closed under adverse conditions,
such as excessive pole deflection, vibration, and galloping conductors,
without the use of blade locks or other latching devices. For the
harsh, unforgiving conditions in transmission operating environments, it is
the most reliable switch available. It is a proven design validated by
over 40 years of successful performance.
The switch is directly connected
to the operating mechanism through the rotating insulators, inter-phase
pipe, lever arms, and crank arms (figure 2), and is in positive control
throughout the complete opening and closing operation. The control
mechanism is designed for efficient transmission of the operating force to
the rotating insulator so that opening and closing of the switch can be
effected in a smooth, continuous motion with minimal operating effort.
Assembly (Jaw) Engagement
The clip assemblies are held open
(figure 3) at approximately 40 degrees by a clutch and double spring
arrangement housed inside the base of the clip assembly. When the
blades swing closed, they engage the contact fingers, pulling the clip
assemblies into the final, closed position. This simultaneous
blade-clip assembly motion enables high-pressure, large contact
deflection to be achieved with minimum operating effort and provides
efficient leverage for breaking ice.
of the blade with the clip assembly (jaw) contact fingers is easily
accomplished with the rocker bottom feature (figure 4) of the blade-hinge
assembly. This feature insures that the blade-end engages the contact
fingers in the vertical center of the clip assembly. Compensation for
insulator tolerances is accomplished, without using shims, by loosening and
tightening two of the four bolts attaching the blade hinge assembly to the
insulators. The two bolts that align parallel with the long axis of
the blade are used for this adjustment, while the other two bolts are used
solely to secure the rocker bottom to the insulator cap.
silver-to-copper contacts give superior conductivity without contact
abrasion and provide ample mechanical and electrical security to meet
industry standard high-current test requirements. The four contact
fingers (figure 5) are hard-drawn copper with silver button-contacts.
Large contact deflection is provided by separate fatigue-resistant backup
springs to maintain high contact pressure under the extreme conditions of
outdoor service. The main current path is through the hard-drawn
copper fingers, not through the backup springs.
The in-line arrangement (figure 6)
of the contact fingers relative to the blade provides increased contact
forces when the switch is subjected to high-current surges. Each
contact finger and backup spring is attached to the jaw-hinge casting with
two bolts, which provides a means for accurately setting contact pressure in
The tubular blade is rigid, hard-drawn copper (figure 7) with a bronze
guide at the blade end. The silver contact buttons engage the blade,
allowing the current to pass directly from the jaw contact to the blade.
Straight-line current transfer from blade to clip fingers provides the
additional advantage of a blade-gripping action under high fault current
Main Bearing Assemblies
The main bearing, which supports the rotating insulator, consists of upper
and lower greaseless ball bearing assemblies, with stainless steel balls and
races. Bearing assemblies are permanently sealed and maintenance free for the life of the switch.
On switches with 3-inch bolt circle insulators (ratings 15-69
bearings are assembled in high-strength aluminum housings (figure 8). The bearing
housings for 5-inch bolt circle switches (ratings 115-161 kV) are of
galvanized steel (figure 9). The 5-inch bolt circle bearings include
four leveling screws to facilitate insulator alignment after assembly onto
Structural Aluminum Frames
Frames are rigid structural-aluminum
units, assembled and welded to form level, stable platforms for mounting the
switch components. Truss-type construction eliminates unnecessary weight and
provides the strength and rigidity to maintain alignment under the loads,
tensions, and operating forces of transmission environments.
Frames for switches rated 15 - 69 kV are of one-piece construction,
requiring no field assembly. Frames for switches rated 115 kV and up consist
of three main assemblies, which are match-marked after factory assembly and
shipped disassembled for convenience in shipping and handling.
Control components incorporate features
to minimize installation time and to maintain ease of operation. They are
designed to withstand the extra force required to break ice and to make sure
that the operating force is delivered effectively to the switch. Control
components typically include pipe couplers, outboard bearings, levers,
cranks, clevises, control rod guides, locking assemblies, swing handles, and ground straps.
Outboard bearing assemblies (figure 10), which support the vertical
pipe column, are of a greaseless, maintenance-free design and employ
stainless steel ball bearings. The number of outboard bearings supplied for
each vertical pipe column is based on the run length and weight of
unsupported pipe. At least one outboard bearing will be supplied per column,
and two may be supplied as the application warrants.
Cranks, clevises, and levers (figure 11) are heavy-duty castings of
high-strength bronze. For maximum mechanical strength and
durability, each component has a large material cross-section and many
incorporate additional ribbing and enlarged embosses.
Hardware (carriage bolts, washers, hex nuts, etc) is structural-grade
Pipe couplers (figure 12) are manufactured from thick wall mechanical
steel tube rather than thin wall pipe sleeves used by other manufacturers.
Combined with self-piercing set screws, they insure that pipe connections
are secure and that switch phases cannot slip out of synchronization.
Adjustable control rod guides are furnished between the
bottom phase and the locking assembly. The control rod guides and locking assembly are slotted for quick,
easy alignment with the vertical control rod.
The locking assembly (figure 13) is stamped with "open"
and "closed" position markings and has provisions for padlocking in either
position. The individual lock segments are heavy-duty castings of
high-strength bronze, and are slotted for easy adjustment and alignment.
A galvanized steel mounting bracket and hardware are also part of this
Ground strap assemblies (figure 14) include a flexible
tinned copper braid, a tinned ground connector, and a pipe clamp.
For more information on specific
product configurations, please select from the links below: