OCB to SF6
Breaker Replacement
A TECO downtown Tampa area substation needed its aging oil circuit breaker replaced with a new SF6 unit. Southern Switch coordinated the crane, removed the old OCB, transported the replacement breaker from TECO’s warehouse, installed it, and ran new protection and control cable. Testing and relay work was completed by field testing partner Sigma C.
SF6 goes in.
Oil circuit breakers have been on their way out of active substations for decades. Maintenance requirements are high, oil handling adds operational complexity, and aging units eventually reach the point where replacement is more cost-effective than continued upkeep. When a TECO substation in the downtown Tampa area hit that threshold, the plan was a clean swap: old OCB out, new SF6 breaker in.
SF6 breakers have no oil to manage, require significantly less routine maintenance, and offer faster interrupting times. For an urban substation where maintenance windows are tight and access is constrained, the transition is straightforward to justify. The field work is the part that requires coordination.
One complete delivery.
A circuit breaker replacement of this type requires two distinct sets of expertise: the physical installation work and the electrical testing and relay commissioning. Southern Switch handled the installation side. Sigma C — our field testing partner for relay and protection work — handled breaker testing and relay coordination. TECO completed authorization and energization.
The partnership keeps the project under a single point of contact without overstating any one party’s scope. When a utility calls Southern Switch, they get the full delivery — not a referral.
- →Contracted and coordinated crane subcontractor
- →Rigging and removal of old OCB
- →Transported new SF6 breaker from TECO warehouse to site
- →Set and installed new SF6 circuit breaker
- →Ran new protection and control cable
- →Circuit breaker testing
- →Relay testing and coordination
- →Provided replacement SF6 breaker from spare inventory
- →Authorization and energization
this transition.
Oil circuit breakers have served transmission and distribution systems reliably for generations, but they carry maintenance demands that SF6 equipment does not. Understanding the tradeoffs is useful context for any utility planning an upgrade program.
- ■Routine oil analysis and oil changes required
- ■Contact inspection and replacement at set intervals
- ■Fire risk from flammable dielectric oil
- ■Longer interrupting times than modern SF6
- ■Parts availability declining for older models
- ■No oil — significantly reduced maintenance schedule
- ■Longer contact life, fewer inspection intervals
- ■No fire hazard from dielectric medium
- ■Faster interrupting times, better fault performance
- ■Smaller footprint on many modern designs
New wiring.
Installing a new circuit breaker without replacing the control cable it depends on is a common shortcut that creates future problems. New P&C cable was run as part of this project — clean connections from the breaker to the relay panel, no splices into aging wire.
Cable runs in an active substation require working within existing tray and conduit infrastructure, routing around energized equipment, and terminating correctly to both the breaker and the relay panel. Southern Switch ran the cable; Sigma C terminated and verified the relay connections as part of their testing scope.
Call (727) 789-0951. Southern Switch handles the physical installation; our field testing partner handles the commissioning. You get one point of contact for the full scope.