MCBs

MCBs, or miniature circuit breakers, are a type of switch used to automatically turn off electrical circuits during abnormal conditions. MCBs often replace fuses in low voltage electrical circuits as they can be more reliable, much more sensitive and are resettable.


How an MCB Works


When continuous overcurrent flows through an MCB, a bimetallic strip is heated and causes it to bend. This bending of the bimetallic strip releases a mechanical latch opening the contacts and turning off the MCB, thereby stopping the current to flow in the circuit. To restart the flow of current the MCB must be manually turned on. This mechanism protects the MCB from faults arising due to overcurrent or overload and is intended to prevent the accidental overloading of the cable in a no-fault situation. The speed of the MCB tripping will vary with the degree of the overload. This is usually achieved by the use of a thermal device in the MCB. The second characteristic is the magnetic fault protection, which is intended to operate when the fault reaches a predetermined level and to trip the MCB within one-tenth of a second. The level of this magnetic trip gives the MCB its type characteristic.


MCBs are used to perform many functions such as local control switches, isolating switches against faults and overload protection devices for installation or specific equipment or appliances.


MCB Types


MCBs have three common types for circuit protection in residential, commercial and industrial applications. The use is classified by a type, which determines the tripping characteristics of the MCB:


Type B - trips between 3 and 5 times the load current


This type will trip instantly at a rate of three to five times its rated current. These are normally used for resistive or small inductive loads where switching surges are very small. Therefore, these are suitable for residential or light commercial installations.


Type C - trips between 5 and 10 times the full load current


This type will trip instantly at a rate of five to ten times its rated current. These are normally used for high inductive loads where switching surges are high such as small motors and fluorescent lighting. In such cases, type C MCBs are preferred to handle higher value of short circuit currents. Therefore, these are suitable for highly inductive commercial and industrial installations.


Type D - trips between 10 and 20 times the full load current


This type will trip instantly at a rate of ten to twenty-five times its rated current. These are normally used for very high inductive loads where high inrush current is very frequent. These are suitable for specific industrial and commercial applications. The common examples of such applications include x-ray machines, UPS systems, industrial welding equipment, large winding motors, etc.


How to select a suitable MCB for the application?


Focus on 3 main points to choose the right MCB for the electrical circuit


  1. Ampere rating

  2. Short circuit breaking capacity

  3. Application type

...
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Description Price Number of Poles Current Rating Model Number Range Series Rated AC Voltage Tripping Characteristics Breaking Capacity Mounting Style Rated DC Voltage Breaking Capacity at Maximum Voltage Rating Length Width Depth
RS Stock No. 791-3341
Mfr. Part No.A9F54210
PHP5,404.11
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2 10A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415V Type C - DIN Rail 100 → 133V 10 kA 85mm 36mm 78.5mm
RS Stock No. 791-3332
Mfr. Part No.A9F54206
PHP5,933.96
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2 6A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415V Type C - DIN Rail 100 → 133V 10 kA 85mm 36mm 78.5mm
RS Stock No. 776-3199
Mfr. Part No.A9N61519
PHP4,710.84
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1 63A - Acti 9 C60H-DC - Type C - - 250V 20 kA - 73mm 81mm
RS Stock No. 746-7706
Mfr. Part No.S202-C6
BrandABB
PHP3,041.48
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2 6A - System M Pro S200 400V Type C - - - 6 kA 88mm 35mm 69mm
RS Stock No. 132-015
Mfr. Part No.2CDS272001R0064
BrandABB
PHP3,870.80
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2 6 A - System M Pro S200 440 V Type C 10 kA - 125V - 88mm 35mm 75.8mm
RS Stock No. 791-3225
Mfr. Part No.A9F53320
PHP8,007.81
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3 20A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415V Type B - DIN Rail 100 → 133V 10 kA 85mm 54mm 78.5mm
RS Stock No. 791-3284
Mfr. Part No.A9F54102
PHP1,941.48
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1 2A - Acti 9 iC60H 100 → 133 V, 12 → 60 V, 220 → 240V Type C - DIN Rail 72 V, 12 → 48V 10 kA 85mm 18mm 78.5mm
RS Stock No. 132-116
Mfr. Part No.2CDS272001R0204
BrandABB
PHP3,061.67
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2 20 A - System M Pro S200 440 V Type C 10 kA - 125V - 88mm 35mm 75.8mm
RS Stock No. 776-8854
Mfr. Part No.A9K24306
PHP1,571.68
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3 6A - Acti 9 iK60N 400V Type C - - - 6000 A - 54mm -
RS Stock No. 132-122
Mfr. Part No.2CDS272001R0164
BrandABB
PHP2,989.88
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2 16 A - System M Pro S200 440 V Type C 10 kA - 125V - 88mm 35mm 75.8mm
RS Stock No. 539-8251
Mfr. Part No.2CDS211001R0324
BrandABB
PHP811.65
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1 32A - System M Pro S200 440V Type C - - 60V 6 kA 85mm 17.5mm 69mm
RS Stock No. 791-3348
Mfr. Part No.A9F54220
PHP5,373.62
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2 20A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415V Type C - DIN Rail 100 → 133V 10 kA 85mm 36mm 78.5mm
RS Stock No. 776-3054
Mfr. Part No.A9N18361
PHP13,646.15
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2 80A - Acti 9 C120N 440V Type C - - ≤250V 10 kA, 20 kA - - 81mm
RS Stock No. 132-071
Mfr. Part No.2CDS272001R0104
BrandABB
PHP2,909.12
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2 10 A - System M Pro S200 440 V Type C 10 kA - 125V - 88mm 35mm 75.8mm
RS Stock No. 791-3228
Mfr. Part No.A9F53310
PHP5,266.42
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3 10A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415V Type B - DIN Rail 100 → 133V 10 kA 85mm 54mm 78.5mm
RS Stock No. 772-1303
Mfr. Part No.5SY4210-7
BrandSiemens
PHP4,690.45
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2 10A - Sentron 5SY4 400V Type C - - - 10 kA 90mm 36mm 76mm
RS Stock No. 791-3398
Mfr. Part No.A9F54332
PHP6,586.87
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3 32A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415V Type C - DIN Rail 100 → 133V 10 kA 85mm 54mm 78.5mm
RS Stock No. 776-8863
Mfr. Part No.A9K24325
PHP1,571.68
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3 25A - Acti 9 iK60N 400V Type C - - - 6000 A - 54mm -
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Mfr. Part No.5SY6106-7
BrandSiemens
PHP1,834.22
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1 6A - Sentron 5SY6 230 V, 400V Type C - - - 6 kA 89.8mm 17.6mm 76.4mm
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Mfr. Part No.5SY7106-6
BrandSiemens
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1 6A - Sentron 5SY7 230 V, 400V Type B - - - 15 kA 89.8mm 17.6mm 76.4mm