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Jinsi ya kukokotoa Circuit Breaker Sizing

Circuit Breaker Sizing ni nini?

Selects appropriate circuit breaker to protect circuits from overcurrent while allowing normal operation. Wrong sizing causes nuisance trips or fire risk.

Fomula

Typical breaker = current × 1.25 (non-motor) or × 2.5 (motor)

Mwongozo wa Hatua kwa Hatua

  1. 1Calculate circuit maximum current
  2. 2Breaker must exceed running current for motor inrush
  3. 3Typical breaker = current × 1.25 (non-motor) or × 2.5 (motor)
  4. 4Match breaker to wire ampacity (wire must handle breaker rating)
  5. 5Select trip curve (A, B, C, D) for application

Mifano Iliyotatuliwa

Ingizo
40A circuit, #8 wire
Matokeo
50A breaker

Makosa ya Kawaida ya Kuepuka

  • Oversizing breaker to avoid nuisance trips (creates fire hazard)
  • Using undersized wire for breaker rating

Maswali yanayoulizwa mara kwa mara

Why not just use larger breaker?

Oversized breaker won't protect from short circuits, creating fire/electrocution risk.

What's the difference between breaker curves?

A: sensitive (electronics), B: general, C: motors, D: high inrush; choose for application.

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