What is toggle?
Toggle is the positioning of the rotating insulator
reach rod, crank arm and clevis assembly into a bind at the end of the
closing operation. The benefit of toggle is that it prevents the
accidental or unintended opening of the switch due to conditions such as
excessive pole deflection or vibration, galloping conductors, insulator
deflection and torque or distortion of the switch support structure.
Toggle is a simple mechanical convention to insure reliability without the
use of blade locks or other latching devices.
Toggle is required for
proper operation of all SEECO switches. Field installation and
switch adjustment are not complete until the switch has been adjusted for
toggle. A more complete description of the toggle adjustment
procedure can be found on pages 14-15 of our
installation instructions for phase-over-phase switches.
2. What is the recommended maintenance for SEECO
Our recommended maintenance is minimal. We recommend
that all switches be operated at least once each year to insure the
freedom of movement of mechanical components and linkages. If this
frequency cannot be met, then operate the switch as often as conditions
permit. Visually inspect all moving components for significant wear
or signs of damage. Male and female contacts should be wire brushed
lightly to restore a clean contact surface area. We do not recommend
the use of contact grease. Observe switch operation and compare the
engagement of live parts, interrupting devices and over toggle components
to the recommended operation as described in the installation
instructions. Operation of the switch should be smooth, with minimal
operating effort to open or close the switch. No slamming is ever
If you have questions after visual inspection and operation,
please do not hesitate to contact SEECO for additional information or
3. Will SEECO coordinate the switch mounting details
with the pole supplier?
Yes. It is a standard procedure for our
application engineers to coordinate the details of switch mounting with
the suppliers of engineered pole structures (steel, concrete, laminated
wood). We forward framing details to the pole supplier and we review
the pole structure drawings submitted to us by the supplier to confirm
correct hole patterns, including number, location and sizes.
We do not review the
design specifications for the pole. This is the responsibility of
the customer or the customer's consultant.
4. Can phase-over-phase
switches be mounted on wood poles?
unique design of SEECO's phase-over-phase GOABS®
withstands changes to wood pole structures more readily than other brands of
phase-over-phase switches, especially those utilizing blade latching type
devices. The "tulip" design of our female jaw contacts is very
forgiving and allows for a significant amount of switch insulator
displacement without loss of contact pressure between male and female
contacts. The toggle
adjustment insures that the rotating insulator stays locked in the
completely closed position, irrespective of the degree of pole structure
and switch frame deflection or switch insulator displacement.
All SEECO phase-over-phase switches rated 69 kV and below can be mounted
on wood pole structures. One-way switches rated 115 kV and up can
also be mounted on wood pole structures. We strongly recommend that
two and three-way switches rated 115 kV and up be mounted on engineered
structures (steel, concrete, laminated wood), designed for the specific
loads and line tensions of the application.
5. Can I dead-end tap and through line conductors directly to the
switch support structure? Won't this cause future maintenance and
For general guidance, you should have no hesitation to dead-end conductors
and strain insulator assemblies directly to the switch frames, unless you
have very severe angular pull-offs or unbalanced line tensions. As
long as through line tensions are equal and balanced, the aluminum or
steel pull-offs provide an economical and convenient means for locating
strain insulator assemblies. Dead-ending conductors directly to the
switch frames also serves to stabilize the support structures.
Unlike other switch designs, which employ blade locks and latching
devices, SEECO's over-toggle adjustment and unique live parts design will
readily accommodate the inevitable twist and deflection of the switch
support structure and insulators that occur with galloping conductors and
pole deflection. And for most ratings and configurations, SEECO's
aluminum frame structures are designed and fabricated utilizing larger
members and thicker material cross sections than the support
structures of our competitors, providing a more rigid and stable platform.
For questions about angular pull-offs and unbalanced line tensions, or
other application specific questions, please contact the factory.
6. What are the ratings or limitations for line tensions?
For general guidance, pull-offs are rated for 10,000 lbs line tension
(working) on a straight line pull, which is 180 degrees on the thru lines
and 90 degrees on the tap. When angular pull-offs are anticipated,
the 10,000 lb line tension allowance must be de-rated. Please
contact SEECO for a table of allowable tensions at various angles or for
guidance on line tension requirements that exceed 10,000 lbs. High
line tension requirements can be accommodated but must be coordinated with
our application engineering personnel.
7. Do you provide installation
Yes. SEECO personnel can provide assistance with
assembly, erection and final product adjustment. Please refer to the
Installation Center for additional
information on commissioning, training or other field support services.
8. Can you provide phase-over-phase switches factory pre-assembled?
Yes. Factory pre-assembled phase-over-phase switches can save
significant field installation time and cost. Factory pre-assembly
also insures that critical assembly and adjustment is made by highly
knowledgeable and experienced personnel.
9. Can you provide live parts for a Turner phase-over-phase switch?
Yes. Live part conversion kits are available for most Turner switch
configurations. SEECO conversion parts replace the existing Turner
components and the modified switch can then be adjusted for toggle.
This is a quick and economical way to eliminate Turner blade locks and the
adjustment problems attendant with them.
10. Can SEECO provide arcing horns for interruption of line charging
SEECO has two styles of arcing horns for transmission switching
applications. Our traditional horn, which is standard on all
phase-over-phase switches, is a tapered beryllium rod that provides
interruption of line charging current comparable to other available arcing
horns. SEECO has also recently developed a spring loaded, high
velocity whip (HVW) that provides substantially higher levels of
interruption than traditional horns. Consult the factory for
assistance in determining which style of horn will best accommodate your
10. Can I close
your switch to pick-up load?
Many customers choose to use the switch to
pick-up load. Though this is not an uncommon industry practice,
please note that the switch is not rated for load make and there may be some
pitting or burning of auxiliary or main switch contacts; the degree of
pitting and burning will depend largely on the line amperage and closing
[It is generally accepted by industry practitioners that the
severity of an arc is substantially less in switch closing than in switch
opening. When closing the switch, the distance between energized
male and female contacts is reduced at a brisk rate and does not present
as favorable an opportunity for an arc to develop as when opening.]
Weighing the operational advantages, disadvantages and safety
considerations, each customer must formulate their own policy for picking
11. Can I close in on a fault?
The answer is
essentially the same as the answer to the previous question. The
switch is not rated for fault closing though some customers choose to do
so. Expect pitting or burning of auxiliary and main switch contacts
proportional to closing speed and the amount of fault current.
Again, each customer must formulate their own policy.
12. What happens if I open your (airbreak) switch to drop load?
You will draw an arc, with the length and duration in proportion to the
speed of opening, the amperage of the line, and the point in the sine wave
where contact separation occurred. Other factors that will affect
the severity of the arc include, ambient temperature, humidity and wind
direction and speed. In severe cases, an elongated or extended arc
may pose a safety hazard to utility personnel and equipment.
If frequent load dropping is anticipated, we recommend the use of SEECO's
Monoruptr(r) vacuum interrupter for arc-less switching.