MCB is widely used in the electrical distribution system for ON/OFF Electrical supply and it also gives over current and short circuit protection. The selection of MCB involved technical, Mechanical parameters. Some parameters are important but some parameters are confusing and mislead to wrong selection of MCB.
Types of MCB based on Number of Poles
Single Pole (SP) MCB
Double Pole (DP) MCB
Triple Pole (TP) MCB
Four Pole (4P) MCB
Three Pole with Neutral [TPN (3P+N) MCB]
Tripping Mechanism in Miniature Circuit Breaker
Thermal Tripping
Magnetic Tripping
MCBs are classified into different types
Type B MCB
Type B MCB mainly used in residential applications or light commercial applications where connected loads are primarily lighting fixtures, domestic appliances with mainly resistive elements.
computers and electronic equipment with very low inrush loads (PLC wiring) Protection and control of the circuits against overloads and short-circuits;
Type C MCB
MCB trips between 5 and 10 times full load current.
Used in a commercial or industrial type of applications where there could be chances of higher values of short circuit currents in the circuit.
loads are mainly inductive in nature induction motors or fluorescent lighting. small transformers, lighting, pilot devices, control circuits, and coils.
Protection and control circuits against overloads and short-circuits; protection for resistive and inductive loads with low inrush current.
Type D MCB
MCB trips between 8 and 12 times full load current.
Suitable for inductive and motor loads with high inrush currents.
The K and D curve breakers are both designed for motor applications where ampacity rises quickly and momentarily during “start-up.”
protection and control of the circuits like motors, transformer, and auxiliary circuits, against overloads and short-circuits.
Type K MCB
Tripping in the case of functional peak currents up to 8xIn, depending on the series; through its highly sensitive thermostatic bimetal trip, the K-type characteristic offers protection to damageable elements in the overcurrent range; it also provides the best protection to 2 cables and lines.
Used in commercial and industrial.
Type Z MCB
MCB trips between 2 to 3 times full load current.
MCBs are highly sensitive to short circuits and are used for the protection of highly sensitive devices such as semiconductor devices.
protection and control of the electronic circuits against weak and long duration overloads and short-circuits.
Used in Commercial and industrial uses.
Before the connection check mcb marking tag for input and Load connection
MCB Characteristic/Trip Curves
MCB Characteristic/Trip Curves
Select appropriate MCB
(A) Current Related:
Frame Size (Inm): Amp
Rated current (In/ Ie): Amp
Ultimate short circuit breaking capacity (Icu): KA
Rated short-circuit breaking capacity (Ics): % of Icu
(B) Voltage Related:
Rated voltage (Ue): Volt
Rated Insulation Voltage (Ui): Volt
Rated impulse withstand voltage(Uimp): KV
No’s of Pole: SP, DP, TP, TPN, FP
(C) Application Type:
Utilization Category/ Characteristic :
B, C, or D curve
(E) Protection Type:
Protection: Over current / Short circuit
Trip Mechanism: Thermal / Magnetic
Trip Mechanism adjustment: Fixed / Adjustable
(F) Others:
Frequency;
Reference temperature:
(if different from 30°C)
Pollution degree:
Suitability for isolation:
Type of Mounting arrangement
Electrical Life Cycles:
Mechanical Life Cycles:
Dimension: mm
Weight: Kg
MCB RATING
1A
2A
4A
6A
10A
16A
20A
25A
32A
40A
50A
63A
Technical Data required for the selection of MCB
Type
Magnetic Release Setting
No. of Poles
Rated Current (In)A
Rated Voltage (Ue)V~
Rated Frequency (f)Hz
Rated Short Circuit Breaking Capacity
Service Short Circuit Breaking Capacity
Energy Limitation
Tripping Mechanism
Normal Ambient Temperature
Power Loss
Rated Impulse Voltage
Dielectric Strength
Protection Class
Mounting
Connections
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