Switchgear Rating Calculator

Calculate switchgear and circuit breaker ratings for PV interconnection based on fault current and system voltage.

Input Parameters

Results

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Transformer Fault Contrib
kA
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Total Available Fault
kA
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Min Breaker Rating
kA
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Nominal Current
A
Note: AIC (Amps Interrupting Capacity) must exceed available fault current. PV inverters contribute limited fault current (1.1-1.5× rated).

Reference

Nominal I = kVA / (kV × √3) Transformer Fault = Nominal I / (Z%/100) Total Fault = Grid Fault + Transformer Fault Breaker Rating ≥ Total Fault × 1.1 (next std size) Standard ratings: 10, 12, 16, 20, 25, 31.5, 40, 50 kA