Side Break Switches Type: 3D Orientation: Transmission pole mounting Ratings: 15 kV through 161 kV Ratings A: 600, 1200, 2000 Ampere Request Bulletin D001 Download PDF Catalog

With their heritage firmly entrenched in similar lines of Transmission switches, Turner "3D" switches are one of the most versatile, severe-duty, pole mounted switching products available. Referred to as "Substation-in-the-Sky" switches, three-way switches eliminate many problems for system designers and reduce construction costs by as much as 60 per cent over conventional ground substation costs.

Unlike many so-called transmission switches that are just substation switches modified for use on a pole, Turner's type "3D" is a true transmission switch. Designed and built for the harsh environmental conditions, galloping conductors and constant pole flexing inherent in severe aerial applications, "3D" switches employ a specially designed, light-weight, 6061-T6 Aluminum frame as a mounting structure. The frame eliminates the need for pole cross arms or braces.

These switches eliminate Right-of-Way and real estate issues, as well as the associated legal considerations. Also eliminated are costly ground structures and several insulator stacks. Turner's unique design requires just 12 insulators versus the 18 required for similar switch applications.

Their flexible mounting ability makes it ideal in phase-over-phase and phase-next-to-phase configurations on transmission poles. Switches rated 69kV and below will mount on any suitable structure; 115kv and above will mount on steel, concrete or laminated wood poles.

Loadbreak vacuum interruption capability is also more affordable on "3D" switch designs, with a "shared" centrally located vacuum bottle stack, instead of one per switching direction.

Transmission switches are extremely difficult and costly to remove from service, so Turner's philosophy is to design in reliability, eliminating the need for constant maintenance.

A rigid, hard-drawn copper blade with patented locking device, silver-to-copper contacts, double-spring arcing horns and sealed hinge contacts provides heavy duty construction.

Add to this Turner's more than 40 years of field proven experience in air break switches and you have maximum switching reliability.

It all adds up to what we call Switch-Ability! Turner Type "3D" switches can be used for station isolating and bypassing, transmission line sectionalizing or preferred/alternate throwovers. Switches are easily upgraded for automatic operation and load break capability.

"3D" Operating Features

Type "3D" switches are operated from ground level with a standard 2" IPS steel vertical operating pipe assembly with a manual swing handle lever. The control lever incorporates a ground shunt, is padlockable and can be supplied for clockwise or counterclockwise operation. A steel shaft with self-piercing set screw clevises is used for coupling and pinning the switch gang control pipe. Motor operators are available for remote, automatic or SCADA control.

Turning the operating lever rotates the main vertical operating shaft, which moves the insulator stack with the blade. The turning motion rotates the blade tip to facilitate a smooth, effortless positive opening motion. This action releases contact pressure within the spring jaw assembly, which helps maintain a clean contact surface, and enhances ice- or contamination-breaking action.

During closing, the main blade contacts remain in the straight or "cammed up" position, allowing effective contact cleaning action. A patented locking device holds the blade securely in the jaw.

Double-spring quick-whips interrupt limited amounts of charging or load currents when opening. Arcing is kept away from main contact surfaces. If the magnitude of the current exceeds the quick-whip capability, a TECO-Rupter full load break vacuum interrupter is available.

Hinge Mechanism
The current carrying path on the hinge end of the switch is continuous and enclosed to permanently protect it from the elements. The terminal pad is threaded to a stationary contact block; the connection is spring-loaded, silver-to-silver. As the switch rotates during the opening and closing cycle, the terminal pad is held in place by the conductor and the switch can move without restriction. Inside the hinge housing, current transfer from the stationary block to the moveable blade is through a series of silver contact fingers. Beryllium-copper backing springs apply continuous pressure around the contact shoes.

This hinge configuration assures maximum service life and minimizes maintenance.

Blade/Jaw Contacts (click for photo)
The high pressure contact shoes are of cast, heat-treated, high-conductivity Beryllium-copper. Although contact pressure is factory-adjusted, should field adjustment ever be necessary, it can easily be made. In addition, contact changeout is fast and easy.

The tubular blade is designed of hard-drawn copper to provide the proper combination of current-carrying capacity and rigidity. The blade tip is Beryllium-copper, heat treated and strato-milled to provide a machined current transfer surface. The coin silver overlay provides high pressure, silver-to-copper contact with the Beryllium-copper jaw surfaces when the tip is in the jaw.

The blade tip engages the jaw contacts in an upright position to form a high-pressure contact. The blade and jaw contacts are wiped clean during the closing action to assure a low resistance current transfer. A patented blade locking device keeps the blade closed despite temporary faults, surge currents, twisting structures or galloping conductors. Double-spring type quick-whips provide time-proven interruption of limited amounts of charging and load currents.

The opening action of the Turner switch is unique. Prior to the blade disengaging from the jaw contact, the blade contact rotates 22 degrees in the jaw. This exclusive Turner action releases all contact friction and breaks any ice or contamination in the jaw area which may impede an easy opening procedure. The Turner switch provides effortless opening regardless of environmental or time effects.

Main Bearing Assembly (click for photo)
The main pivot bearing assembly consists of two tapered Timken roller bearings, which are adjusted and lubricated at the factory and require no further attention for the life of the switch. These bearings are protected with a Neoprene seal and permanently sealed at the bottom with a Welsh-type expansion plug. This unit will accommodate cap-and-pin or post-type insulators without the use of an extra casting.

Four leveling screws are provided on the sub-base of each insulator stack, to facilitate easy alignment after assembling the insulators on the switch. Adjusting the screws raises or lowers the end of the switch blade and orients the blade to jaw contact interface correctly.

Tightening the insulator bolts holds the alignment fast. Leveling screws are also provided on all stationary insulator pedestals.

Mounting Flexibility
To accommodate the variety of transmission structures and locations, Turner offers a similar variety of operating and mounting configurations. Controls can be supplied for clockwise of counterclockwise opening if requested, or may be changed in the field as necessary.

Turners standard operating mechanisms for side-break switches consist of vertical steel operating pipe, with or without an 8-foot fiberglass insulating section; a steel or fiberglass interphase shaft, with self-piercing set screw clevises for coupling and pinning to switch crank arm and vertical pipe guides.

Full Load Vacuum Interrupters

The Turner TECO-Rupter is a vacuum circuit interrupter that is offered as an attachment to the Turner switch as well as designs of other switch manufacturers. It is offered in three (3) basic configurations and can be attached to vertical break, side break, hookstick and some center break switch designs. The configurations are as follows:

1. Loop or parallel break - Normally these are single vacuum contact devices, which can interrupt up to 2000 Amps, up to 230 kV, under paralleled conditions (i.e., rated voltage exists on both the hinge and jaw of the switch immediately after the interrupter is opened.) The transient recovery voltage must not exceed 30 kV for the single contact. More contacts can be added to address higher recovery voltages; consult factory.
2. Line/bus charging/line sectionalizing interruption/transformer magnetizing current interruption - A full voltage multiple stack interrupter may be utilized from 15 kV through 230 kV for interruption of line or bus charging currents and transformer magnetizing currents up to a value of 70 Amps at 0% power factor, capacitive or inductive. The nameplate operating current of the switch is not a factor in the application of this device.
3. Load interruption - A full voltage multiple stack interrupter may be applied from 15 kV through 230 kV for interruption of actual current at 70% power factor.

The TECO-Rupter is only in the circuit during the opening sequence, (normally one [1] to [2] seconds in duration.) Also, contact test studs on the exterior of the enclosure allow you to independently Hi-Pot each vacuum contact when the actuating arm is in the open position at 30 kV.