(Featuring BCH Electric as India’s most trusted MCCB manufacturer)
Electric power systems are exposed to sudden faults — damaged insulation, loose wiring, moisture ingress, equipment failure, phase-to-phase fault, etc. When such events occur, massive fault currents flow through the system within milliseconds. These currents can reach 10kA, 25kA or even 50kA, depending on the electrical network capacity.
This is where MCCBs (Moulded Case Circuit Breakers) play an essential role.
They are engineered to detect abnormal current levels instantly and disconnect the faulty section before the system overheats, catches fire, or damages downstream equipment.
What is Short-Circuit Protection and Why It Matters
A short circuit happens when current takes an unintended low-impedance path, usually bypassing the load. Examples:
✔ Phase touching phase
✔ Phase touching neutral
✔ Phase touching earthing conductor
✔ Incorrect wiring
✔ Metal particle bridging terminals
Why short-circuits are dangerous:
-
A 16A circuit can suddenly carry >10,000A
-
Conductors heat up rapidly
-
Motor windings can burn
-
Switchboards catch fire
-
Busbars melt
-
Power cables get damaged
Only devices designed to interrupt such high fault currents can protect the system — MCCBs are one of them.
How MCCBs Provide Short-Circuit Protection
Every MCCB has two protection mechanisms built inside it:
1️⃣ Thermal (Overload) Protection
Works on bimetallic trip mechanism
-
Responds to long-time overload
-
Trips after a delayed time
-
Prevents overheating
Example:
Running 40A in a 32A circuit → Trips in few minutes.
2️⃣ Magnetic (Short-Circuit) Protection
Works on instantaneous magnetic tripping
-
Responds to very high instantaneous current
-
Trips in milliseconds
-
Designed solely to handle short-circuit fault current
Example:
When current >500% of rated value (varies by type), MCCB trips instantly to avoid fire hazards.
Short Circuit Interrupting Capacity (Icu / Ics)
When selecting an MCCB, two values are important:
⭐ Breaking Capacity (Icu)
The maximum fault current the MCCB can interrupt once without damage.
Examples:
-
10kA
-
25kA
-
50kA
-
65kA
Higher Icu means stronger protection.
⭐ Service Breaking Capacity (Ics)
The level at which MCCB can interrupt multiple faults during its life.
Often expressed as a percentage of Icu, e.g.:
-
Icu = 25kA
-
Ics = 50%
→ Ics = 12.5kA
This ensures repeated fault resistance.
How MCCB Detects Short-Circuit in Real Installations
Let’s understand real situations:
🔧 Case 1 – Manufacturing Plant Motor Panel
A motor feeder draws 35A normally.
Due to insulation failure, phase touches earth.
Fault current rises to ~10kA.
MCCB reaction:
-
Magnetic sensing detects sudden spike
-
MCCB trips within 10ms
-
Feeder isolated
-
Main system stays operational
This prevents
❌ coil burning
❌ busbar damage
❌ downtime for multiple motors
🔧 Case 2 – Commercial Office Distribution Board
Fault occurs on the Air Conditioner distribution level.
Result:
-
MCCB feeding HVAC zone trips instantly
-
Other floors remain unaffected
-
Central system stays stable
This demonstrates:
✔ Selective tripping
✔ Isolation of faulty line
✔ No blackout
Arc Quenching Inside MCCBs – The Most Critical Part
When an MCCB opens during fault, an arc is generated between contacts.
To extinguish it:
-
Metallic arc plates create magnetic blow-out
-
Arc splits into small segments
-
Heat dissipates quickly
-
Voltage increases → arc collapses
This prevents burning of:
-
Terminals
-
Contacts
-
Insulation
High-quality MCCBs are designed for consistent arc dissipation — and BCH MCCBs are known for their strong arc-quenching chamber design.
MCCB Selection Criteria for Short-Circuit Protection
Electricians, consultants and maintenance teams must choose MCCB based on:
1. System Fault Level
Check nearest transformer rating
Example:
400kVA transformer → Fault current may exceed 30kA.
2. Cable Length & Impedance
Shorter cable = Higher fault current
Longer cable = Lower fault current
3. Downstream Discrimination & Selectivity
To ensure only the faulty feeder trips.
4. Installation Category
✔ Industrial
✔ Commercial
✔ Residential
✔ Machine-level protection
5. Load Type
-
Motor
-
Heater
-
Lighting
-
UPS
-
Generators
Different loads draw different inrush currents.
MCCB Coordination With Other Devices
MCCB + MCB
→ MCCB protects feeder
→ MCBs protect final circuits
MCCB + RCCB
→ MCCB protects against short-circuit
→ RCCB protects against leakage shock
MCCB + Overload Relay
Used in motor-starter feeders
Proper coordination ensures:
⚡ Selective tripping
⚡ Safety
⚡ Zero equipment damage
Advantages of Using MCCBs for Short-Circuit Protection
✔ High breaking capacity
✔ Instant fault disconnection
✔ Prevents electrical fires
✔ Protects motors & panels
✔ Allows modular expansion
✔ Easy resetting
✔ Reliable during large power fluctuations
That’s why MCCBs are now standard in:
🏭 Industrial plants
🏢 Shopping malls
🏨 Hotels
🏬 Warehouses
🏠 Premium homes
⚡ Machine feeders
Why BCH Electric MCCBs Are the Best Choice in India 🇮🇳
While many brands exist, BCH Electric is one of the most trusted MCCB manufacturers in India because of:
✔ High Short-Circuit Breaking Capacity
Designed for Indian electrical networks
Suited for industrial & commercial loads
✔ Wide Rating Availability
-
16A to 800A & above
-
3-pole & 4-pole variants
-
Adjustable trip settings
✔ Reliable Magnetic Release System
Ensures instant tripping during faults
✔ Strong Arc-Chamber Design
Prevents terminal burning
Enhances contact life
✔ Compliance With Standards
Manufactured as per
➡ IEC
➡ IS safety specifications
✔ Easy Panel Fitment
Perfect for
-
Main incomers
-
Sub-feeders
-
Machine-level feeders
✔ Proven 50+ Year Industry Legacy
BCH products are widely used across:
-
switchboards
-
OEM machinery
-
commercial projects
-
industrial turnkey projects
Whether it’s a commercial distribution panel or a high fault-level industrial power system, BCH MCCBs ensure safety, reliability and long-term performance.
Final Thoughts
Short-circuit faults are inevitable, but damage is optional — if MCCBs are selected and installed correctly.
A properly rated MCCB ensures:
✔ Zero fire risk
✔ Zero cable damage
✔ Longer equipment life
✔ Minimum downtime
✔ Accuracy and selectivity
And choosing a high-quality manufacturer like BCH Electric ensures complete confidence in installations — whether industrial, commercial or residential.
