How do I select the right circuit breaker rating?

The breaker rated current must satisfy: I_load ≤ I_breaker ≤ I_cable. Select the next standard rating above load current (6, 10, 16, 20, 25, 32, 40, 50, 63 A for MCBs). The breaker must also not exceed the cable's current carrying capacity.

What is the difference between trip curves B, C, and D?

Trip curves define the instantaneous magnetic trip threshold. B curve: 3-5× rated (resistive loads, lighting). C curve: 5-10× rated (general loads, small motors). D curve: 10-20× rated (motors, transformers with high inrush).

What is breaking capacity and why does it matter?

Breaking capacity (kA) is the maximum short-circuit current the breaker can safely interrupt. It must exceed the prospective fault current at the installation point. Typical values: 6 kA residential, 10-25 kA commercial, 36-50+ kA industrial.

What is the difference between MCB and MCCB?

MCB (Miniature Circuit Breaker): up to 125 A, fixed settings, for branch circuits. MCCB (Moulded Case Circuit Breaker): up to 2500 A, adjustable trip settings, higher breaking capacity, for feeders and main distribution.

How do I coordinate breakers for selective tripping?

Selectivity (discrimination) ensures only the breaker closest to the fault trips. Rules: upstream breaker should have higher rating, slower trip time, and the ratio of rated currents should typically be ≥ 1.6:1 for MCBs of the same curve type.

मुक्त अभियांत्रिकी साधन

Circuit Breaker Selection Calculator

MCB/MCCB रेटिंग, ट्रिप कर्व्ह (B/C/D) निश्चित करा आणि ब्रेकिंग क्षमतेची पडताळणी करा. नियम: I_भार ≤ I_{ब्रेकर} ≤ I_केबल.

IEC 60898IEC 60947B / C / D कर्व्ह

डिझाइन लोड करंट (A)

केबल करंट रेटिंग (A)

अपेक्षित शॉर्ट-सर्किट (kA)

लोड प्रकार

Quick presets

Results

शिफारस केलेले ब्रेकर रेटिंग

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ट्रिप कर्व्ह

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किमान ब्रेकिंग क्षमता

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ब्रेकर प्रकार

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समन्वय तपासणी

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निवड नियम

ट्रिप कर्व्ह (IEC 60898)

कर्व्ह	मॅग्नेटिक ट्रिप	अनुप्रयोग
B	3–5 × I_n	रेसिस्टिव्ह लोड्स, लांब केबल्स
C	5–10 × I_n	सामान्य उपयोग, लहान मोटर्स
D	10–20 × I_n	मोटर्स, ट्रान्सफॉर्मर्स, उच्च इनरश

⚠️ Note: हे साधन फक्त मार्गदर्शन देते. अंतिम निवड सर्व प्रतिष्ठापन अटी विचारात घेऊन पात्र विद्युत अभियंत्याकडून पडताळली जाणे आवश्यक आहे.