LTC Expertise

Load Tap Changer (LTC) Kits, Overhauls and Upgrades

When design, manufacturing and testing of new components have all been completed and the product hits the market, that’s when our work begins—manufacturing replacement parts, evaluating performance of original designs and redesigning components to improve performance and enhance reliability. In addition to being the OEM for the field-proven and dependable Waukesha® UZDvac® load tap changer, Prolec GE Waukesha is committed to becoming the industry’s preferred supplier of replacement parts and service for all LTCs, utilizing design and reverse-engineering skills, quality control and value-added manufacturing processes.

Contact Kits, Tool Kits & Components

Prolec GE Waukesha offers an extensive selection of make/model replacement contacts, including low resistance contacts. Many of these are available in our extensive selection of maintenance parts kits available for most major and obsolete load tap changers. These kits, designed based on customer feedback, include most parts that wear out or need replacement. Standard maintenance kits include all respective movable and stationary contacts for all three phases of the equipment. We maintain a large inventory of these kits for emergency deliveries.

Unique maintenance tool kits help provide for faster, easier servicing of load tap changers. Each kit contains custom tools specific to a given LTC make/model along with instructions to aid in installation and calibration/adjustment of replacement contacts.

We currently offer tool kits designed specifically for use on the following LTCs: Waukesha® UZD®; RMV-II; FPE TC-546, TC-525, TC-523, TC-25, TC-46; McGraw 550, 550B, 550C; GE LRT200 Series.

In addition to contacts and tool kits, our Components Group offers a variety of “non-standard” parts, such as tap head castings, gasket kits and drive shafts, while leading the industry in the ability to reverse-engineer and manufacture insulating barrier boards and phase panels on short notice from a customer-supplied sample for single and three-phase load tap changers. Our large inventory of barrier board materials in a variety of thicknesses and sizes allows us to support our customers’ emergency needs.

Overhauls & Upgrades

Our company defined the standards for high quality and reliable load tap changer overhauls/upgrades, starting with our industry-leading conversion and overhaul of the GE LRT200 in 1994. This overhaul and the many years of experience gained since then have given Prolec GE Waukesha the knowledge and expertise to develop thorough and comprehensive LTC refurbishment programs for the following models:

  • General Electric LRT200, LRT200-2, LRT68, LRT72, LRT38/48
  • McGraw 500, 550B, 550C
  • Siemens TLF, TLG, TLH20, TLH21, TLS
  • Moloney MA/MB, MA1/MB1, MA2/MB2
  • Westinghouse UTS, UTS-A, UTT, UTT-A, UTT-B
Our Standard Rebuilt Scope Includes the Following Steps:
  • Preparation of a written scope of repair specific to make/model of LTC being overhauled.
  • Thorough receiving inspection documents condition and assist in determining most probable failure mode.
  • Complete disassembly of the entire mechanism and evaluation of all parts for wear condition and probable failure damage.
  • Inspection and cleanup of all drive gears and LTC assembly frame (most are reused on the rebuilt LTC).
  • Replacement of all locking hardware, springs and pivot bushings.
  • Hi-pot and wear evaluation of vacuum interrupters (if present).
  • Inspection and cleanup of all control wires and terminations, limit switches and motor drive/spring charge mechanism.
  • Electrical testing and verification of operation of drive motors and limit switches.
  • During rebuild, all newly installed contact assemblies are adjusted and calibrated to ensure proper operation.
  • After rebuild and timing, all spring-loaded contact assembly pressures and contact resistance measurements are recorded and evaluated to ensure contacts are mating properly on all positions.
  • Depending on the model, a final verification of operation is performed in a tank under transformer oil for up to 25,000 mechanical operations across the entire tap range.
  • Each unit overhauled by our Components Group is warranted for 12 months from defects in materials and workmanship.
  • Final repair report details all items replaced/reused and a failure analysis showing “as received” condition and mode of failure is available upon request.

Prolec GE Waukesha also stocks completely rebuilt LRT200-2 LTCs in Dallas, Texas, for quick delivery.

Waukesha® UZDvac® Load Tap Changers

After more than 50 years of offering the Waukesha UZD® load tap changer, the time has come to replace it with the Waukesha UZDvac®. The Waukesha UZDvac® is a high speed, resistive bridging on-tank tap changer utilizing vacuum interrupter technology.

Key features and benefits of the UZDvac®:

  • All arcing takes place inside the vacuum interrupters
  • Eliminates the main cause of contact erosion and oil contamination
  • Eliminates the need for an oil filtration system
  • Reduces maintenance costs
  • Extends service life
  • No by-pass switches required – resulting in a simpler and more reliable design
  • Preventive autotransformer not required due to use of a transition resistor for bridging
  • Spring driven mechanism ensures UZDvac® is not left in the off position if control power is lost during a tap operation
  • Modular design allows for quick field repairs and reduces parts inventory
  • In the unlikely event of a vacuum interrupter failure, the UZDvac® will safely and automatically revert to arcing in oil – allowing for seamless voltage regulation, thus enabling the user to take a planned outage for repairs.
  • Mechanically and electrically tested to over 1,000,000 operations and compliant with IEEE C57.131-2012 Standard Requirements for Tap Changers

For applications greater than 750A, Prolec GE Waukesha will utilize power-class series transformers to reduce current levels passing through the contacts, thereby limiting arcing intensity and duration and extending LTC life. Power-class design means the series transformer will have circular core/coil construction with disc or helical type windings.

Warranty and aftermarket support for the UZD® will continue to be provided through the Waukesha Components Group based in Dallas, TX. Our Service teams can provide field support and may also help with field retrofits to the UZDvac®.

Man working on LTC in Manufacturing Facility Man using a PDA Material Analyzer LTC Spring with Computer Analysis Waukesha UZDvac with door open

Contact Us

For product specific questions or concerns, please call 800-338-5526 or fill out our Components Request Form. You can also browse our easy-to-use 3D Components Catalogs that will help you quickly locate and purchase that hard-to-find LTC part, oil circuit breaker component or Transformer Health Product® you’ve been meaning to source.