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Phase-Over-Phase GOABS®
This switch configuration is designed specifically for
mounting on a single pole structure with conductors oriented in the
vertical plane, either phase-over-phase or phase delta.
Phase-over-phase switches provide very economical
sectionalizing and circuit control at tap and tie switching points.
Mounted on a single pole structure in the line, their use can minimize
line right-of-way requirements and significantly reduce the costs of land
and equipment associated with conventional substation switching.
Phase-over-phase GOABS® utilize
side-break style switches, mounted horizontal upright on aluminum support
structures. The switch is designed for maintenance-free operation in
severe environmental and operating conditions. The operating effort
to open and close the switch is minimal, even at higher voltages; no
slamming is ever required. The switch is positively toggled when in
the fully closed position, so 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.
Tie and Tap Switching - the
economics of 'bundling'
Two-way and
three-way
phase-over-phase switches employ a multiple-switch concept where
individual switch pole units are arranged in an integral design, sharing
insulators, interrupters, and other switch components. Because
components are shared, the cost of switching becomes proportionally less
expensive when compared to other conventional switch configurations.
In addition, the combining of
two or three switches into one 'bundle' provides a single location for tap
or tie circuit control, whether local, remote, or automatic. This
facilitates the addition and use of automation equipment, such as
motor
operators, rtu's, and line sensors, which support switch operation through
supervisory control or auto-sectionalizing. Like the sharing of
switch components, the sharing of automation equipment makes the cost of
control proportionally less expensive.
Selection Criteria
System designers will typically
use some combination of the following selection criteria to choose the
configuration of phase-over-phase switch that best serves their
application requirements:
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One-way: Used for basic
sectionalizing, breaking long lines into smaller, more manageable
segments.
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Two-way: Used for circuit
control at through line tap and tie points, where switching is required on
both sides of the through line but switching the tap line is not. To
drop or isolate the tap, both switches on the through line must be opened,
breaking the feed through.
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Three-way: Used for circuit
control at through line tap and tie points, where switching is required on
both sides of the through line and the tap line. Three-way switches
allow the tap to be dropped or isolated while maintaining the feed
through.
Phase-over-phase Center Vee
Center Vee switches can also be
used for economical sectionalizing on a single pole structure, mounted
phase-over-phase or phase delta and are an alternative to traditional
one-way, phase-over-phase switches. Center Vee switches are best
used where the system designer's primary concern is to a) minimize the
height of the pole structure and b) he or she can live with more limited
interruption devices, such as arcing horns and single bottle interrupters
[where load dropping is not required now or in the future.]
Center Vee switches are
appropriate for circuits rated 46 - 138 kV. For 161 and 230 kV
applications, we strongly recommend use of the traditional
one-way,
phase-over-phase GOABS®, which have been demonstrated to be more stable
and mechanically reliable at these higher voltages.
Horizontal Cross-Arm or
Truss Mounting
Not all transmission switching
applications are phase-over-phase (vertical) on a single pole structure. For
those applications where the group operated switch is mounted on
horizontal cross-arms or a truss type structure, SEECO supplies a number
of different switch configurations depending on the required phase
spacing, clearance considerations and interrupter requirements.
For customer convenience, SEECO
can supply aluminum and galvanized steel truss structures for one, two and
three pole applications. We can also ship the group operated switch
fully assembled on the SEECO-supplied truss structure, ready for
immediate installation upon delivery.
Interruption Devices
SEECO manufactures a wide range
of interruption devices to meet your complete sectionalizing requirements.
These interruption devices are available for most transmission switch
configurations and mounting applications. Please refer to the
interrupter overview section for a
more complete description of these devices.
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High-speed, snap-out arcing
horns are standard equipment on all transmission switching applications.
Fabricated from beryllium tube, the rod is tapered for high tip speed
during the first cycle after separation. They are suitable for
interruption of limited amounts of line charging and transformer
magnetizing currents.
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For interruption of substantially greater amounts of line
charging current, SEECO has developed the High Velocity Whip (HVW),
a spring loaded, stored energy arcing horn, which achieves a very large
air gap within the first cycle after separation.
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For loop switching applications (parallel break), SEECO manufactures a single bottle interrupter. The
interrupter has a maximum interruption capability of 30 kV peak and 3000
amps.
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For maximum sectionalizing flexibility, SEECO manufactures
multi-bottle
vacuum interrupters that provide a broader range of interrupting
capability in a single device, including load dropping, line dropping and
loop splitting.
Sectionalizing Automation
In response to the
growing industry interest in transmission automation, SEECO has developed
an integrated suite of products that complement and support the automation
of group operated switches. The overall theme of these products is
to facilitate the rapid identification and isolation of faults and the
restoration of service. This can be accomplished in conjunction with an
existing supervisory control system or through independent, automatic
switch operation.
SEECO automation products are compatible with any brand or configuration of group
operated switch and include the following products operating individually
or in combination:
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Motor operators
- controlled by remote supervisory systems or by local logic devices
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Line sensors
for monitoring and reporting transmission line status and
condition, including voltage-only, current-only and combination current
and voltage units
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Local logic devices - local processing of line sensor output
signals, which are compared to stored threshold parameters; enables independent automatic sectionalizing of switches
Please refer to the
Automation and Control
Overview webpage for a more complete description of our capabilities
and devices.
Switch Construction Details
For more complete, detailed information on
transmission switch product features and functions, please view the Construction Details
page.
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