Kaip apskaičiuoti Circuit Breaker Sizing
Kas yra Circuit Breaker Sizing?
Selects appropriate circuit breaker to protect circuits from overcurrent while allowing normal operation. Wrong sizing causes nuisance trips or fire risk.
Formulė
Typical breaker = current × 1.25 (non-motor) or × 2.5 (motor)
Žingsnis po žingsnio vadovas
- 1Calculate circuit maximum current
- 2Breaker must exceed running current for motor inrush
- 3Typical breaker = current × 1.25 (non-motor) or × 2.5 (motor)
- 4Match breaker to wire ampacity (wire must handle breaker rating)
- 5Select trip curve (A, B, C, D) for application
Worked Examples
Įvestis
40A circuit, #8 wire
Rezultatas
50A breaker
Common Mistakes to Avoid
- ✕Oversizing breaker to avoid nuisance trips (creates fire hazard)
- ✕Using undersized wire for breaker rating
Frequently Asked Questions
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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