Unitized Transmission Switches – Concept and Benefits

Utilities are choosing to outsource transmission line construction projects to contractors, as in-house resources have dwindled due to retirements and attrition of personnel.  With the departure of the personnel went considerable knowledge and experience and while line contractors are proficient in T-Line construction methods and procedures, that knowledge is typically skewed towards general line work, not the more nuanced brand and product specific procedures needed for proper disconnect switch adjustment

To address this challenge, SEECO supplies a full array of unitized transmission line switches, which are designed to simplify installation and reduce total overall installation time and cost.  SEECO unitized transmission switches are fully assembled and adjusted on a common tube or truss and include factory adjustment of the interphase pipe and associated levers, cranks, clevises, along with synchronous operation of all three phases and switch closed ‘toggle’.  As a result, the line crew’s scope of work is reduced to simply mounting the unitized assembly to the pole structure, hanging the vertical control pipe, and landing and tensioning the conductors. 

Customers that purchase our unitized transmission switches receive a consistently uniform product that is factory adjusted to proper specification, eliminating field adjustment steps that can confuse and sometimes frustrate less experienced line personnel.  Long term reliability and switch performance issues are eliminated, delivering the lowest total cost of ownership and higher customer satisfaction.

Major Benefits

• Reduced installation time, typically 4-5 hours total time
• Reduced total installation cost – typically 30% or greater, due to reduced crane hours, crew time and overheads
• Elimination of field adjustment errors – brings critical field adjustment procedures back into the factory, where factory trained personnel make these adjustments
• Smoother operating effort, fewer maintenance issues and longer operating life compared to non-unitized switches that may not be properly field adjusted per manufacturer’s installation and adjustment specifications

Additional Benefits

• For wood pole structures, the galvanized steel unitizing tube acts as a stiffener, greatly reducing or eliminating problems associated with twist, deflection or contraction in the critical section of the pole where the switch single phases are located; restores wood pole structures as a viable option for switch pole applications, reducing overall application cost
• Unitized switches can be supplied for any customer structure and mounting application requirement, including phase-over-phase, H-frame and pole top

To complete your project requirements, SEECO unitized switches can be supplied with SEECO motor operator, interrupter and line sensor devices.