BZO 63kA uprate


Substation equipment life extension solutions


Aging infrastructure, changing workforce demographics and an increasing emphasis on reliability present new challenges for the modern utility organization. Based on recent transmission planning studies, many utilities are finding that their future substation fault duty requirements may exceed the maximum fault duty of their current high-voltage breakers.

Siemens has designed an uprate solution for BZO6 115 – 138kV and BZO 242-3kV high-voltage oil circuit breakers to increase fault duty rating from 40/50kA to 63kA. To perform the uprate, the existing moving and stationary contacts assemblies are removed. The aluminum cylinder is replaced with a manganese bronze cylinder. The eight-finger contact assembly is replaced and upgraded to a 10-finger assembly to provide additional contact surface.


Turnkey maintenance


Siemens can perform the uprate on a turnkey basis. We provide a field service
project engineer, all labor, tools, and test equipment to perform major maintenance and uprate per OEM specifications. Customers receive a new 63kA nameplate and 12 month limited warranty.

  • Place additional lock and tag on disconnect switch to isolate breaker

  • Perform “as found” tests on the breaker (timing, ductor, and oil analysis)

  • Remove and store oil from the circuit breaker onsite

  • Remove stationary and moving interrupter assemblies for inspection

  • Perform site inspection to ensure the stationary interrupter shells can be reused and moving contact assembly structures are satisfactory for refurbishment

  • Inspect operator assembly and pump/reservoir for leaks

  • Change oil in reservoir and replace hydraulic filter as applicable

  • Replace moving and stationary interrupter assemblies excluding resistors

  • Check auxiliary switch and lightly lubricate bearings and coupling linkage

  • Test insulating oil before refilling

  • Filter press insulating oil before refilling breaker tanks

  • Complete uprate checklist per OEM specifications

  • Complete all operational and electrical tests

  • Submit maintenance and uprate reports.