Circuit Breaker: Learn the Purpose, Cost, and Lead Time to Procure

Circuit Breaker

Purpose of circuit breaker

  • Break the power flow
  • Contain the arcing within its chamber and extinguish it

Where you install the circuit breakers and the quantity depends on the bus configuration, as seen below.

circuit breaker install location in a ring bus station
Circuit breakers (in yellow boxes) in a ring bus substation.
Circuit breakers (in yellow boxes) in a breaker and a half substation.
Circuit breakers (in yellow boxes) in a breaker and a half substation.

What happens when you break a high voltage circuit without special provisions? Take a look below. Uncontrolled arcing is destructive and unsafe.

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500KV energized circuit interrupted using a switch

Cost of circuit breaker

  • 365kV dead tank gas breaker: ~$200,000
  • 138kV dead tank gas breaker: ~$100,000
  • 69kV vacuum breaker: ~$50,000
  • 15kV vacuum breaker: ~$25,000

You may be interested in switching capacitive loads using Independent Pole Operating (a.k.a. zero crossing) circuit breaker. 365kV breakers are inherently IPO. The synchronous controller costs an additional ~$20,000. To make 138kV breakers IPO, it costs roughly double.

Lead time to procure circuit breaker

~6 months

Information on cost and lead-time are rough estimates – contact vendor with your equipment specifications for actual figures.


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Substation Major Equipment

It’s only stupid-simple, let’s begin.

You are building an interconnect station, tying wind farm generation to the power grid. At the substation, the sources are tied through a tie-breaker. Which device would you install to make sure the sources are synchronized?
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A transformer develops an internal fault. Which device would you install on the transformer high-side to interrupt fault current?
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What’s the purpose of a conventional power transformer?
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Which combination of devices would you use to implement power line carrier?
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An industrial facility is plagued with voltage flicker and poor power factor at the service entrance. Which device would you install to fix both issues?
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In a distribution substation, the available ground-fault current on the low side of the step-down transformer is excessive, over-dutying the switching equipment. What is your cost-effective solution to reducing the fault current?
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For which event should a surge arrester operate? Check all that apply.
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