Upgrading your UTT, UTT-A or UTT-A70 to the UTT-B Style Selector Switch
In this installment, we will discuss upgrades for the selector switch assembly of your Westinghouse UTT Series load tap changer (LTC). These upgrades address areas of the selector switch that are prone to failure due to overheating and carbon buildup and are applicable to the UTT, UTT-A and UTT-A70 models.
Each phase of a 3-phase LTC contains a selector switch. Below are 3-D models of individual phase panels for each of the different UTT Series LTC models. Red arrows indicate areas where overheating and coking typically occur. These arrows also help visually identify areas where there are differences in the designs of the individual models.
Figures 1 and 2 below depict the flip side of the moving contact arm assembly in which the contacts are clearly visible. Arrows indicate areas of the moving contact arm assembly where overheating and carbon buildup are most likely to occur. Figure 1 depicts the UTT model and Figure 2 depicts the UTT-A/UTT-A70 models.
By upgrading the moving contact assembly of the UTT, UTT-A, UTT-A70 to the UTT-B design, the risk of overheating and carbon buildup in the contact areas is fundamentally reduced. Figure 3 below depicts the contact arm assembly of a UTT-B with the contacts exposed. The upgrade to the UTT-B design reduces the number of contact fingers from four (4) to two (2) and the number of non-wiping fingers from four (4) to zero (0).
In addition to the upgraded contact configuration, the collector rings on the UTT-B design are offered in an improved “split” design for phases A and B. Figure 4 below indicates the position of the collector rings. The split design allows for worn collector rings on phases A and B to be replaced in the field without untanking the LTC.
Form, fit and function are exactly the same between the different designs, but the selector switch upgrades presented above offer the following benefits:
- 50% reduction in spring-loaded contact fingers, reducing risk of overheating and coking
- Elimination of all non-wiping spring-loaded contacts, reducing risk of overheating and coking
- Significant reduction in time required for collector ring replacement without untanking the unit
Each upgrade kit from SPX Transformer Solutions’ Components Group comes with detail ed instructions for installing the upgraded designs. We also offer standard and customized component kit cases. These cases offer the following unique set of benefits:
- Parts are easier to pull from inventory and issue to the maintenance jobs
- All key parts are included for easy and safe transport to the work location
- No need for field personnel to keep lists of components consumed during maintenance
- Cases provide a better means of protection and storage for the components
- Quick and easy to replenish after completion of field maintenance
Our 30 year history of providing replacement parts for the majority of OEM LTCs has allowed us to develop the capability to confidently engineer, manufacture and support a myriad of design-enhanced replacement parts. You can be confident that the SPX Transformer Solutions’ version of the UTT-B style selector switch components will match the performance of the OEM part at a fraction of the cost.
Similar upgrades are available for the UTT, UTT-A and UTT-A70 transfer switches. These other upgrades will be covered in detail in the third installment of this three-part Tech Tip series.
To learn more about all upgrades available for the UTT Series LTC contact a member of our sales team at 1-800-338-5526. Also, don’t forget about our library of easy-to-navigate, 3D catalogs designed to help you quickly identify and locate hard-to-find components for LTCs and oil circuit breakers, while also including one for the SPX Transformer Solutions’ line of Transformer Health Products®.Download Now