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 Length Width Depth Application
RS Stock No. 791-3341
Mfr. Part No.A9F54210
PHP3,389.29
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2 10 A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415 V Type C 10 kA DIN Rail 100 → 133V 85mm 36mm 78.5mm -
RS Stock No. 791-3332
Mfr. Part No.A9F54206
PHP3,743.18
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2 6 A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415 V Type C 10 kA DIN Rail 100 → 133V 85mm 36mm 78.5mm -
RS Stock No. 776-3199
Mfr. Part No.A9N61519
PHP4,503.78
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1 63 A - Acti 9 C60H-DC - Type C 20 kA - 250V - 73mm 81mm -
RS Stock No. 791-3225
Mfr. Part No.A9F53320
PHP4,099.01
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3 20 A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415 V Type B 10 kA DIN Rail 100 → 133V 85mm 54mm 78.5mm -
RS Stock No. 791-3284
Mfr. Part No.A9F54102
PHP1,649.81
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1 2 A - Acti 9 iC60H 100 → 133 V, 12 → 60 V, 220 → 240 V Type C 10 kA DIN Rail 72 V, 12 → 48 V 85mm 18mm 78.5mm -
RS Stock No. 776-8854
Mfr. Part No.A9K24306
PHP1,571.68
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3 6 A - Acti 9 iK60N 400 V Type C 6000 A - - - 54mm - -
RS Stock No. 791-3348
Mfr. Part No.A9F54220
PHP3,309.06
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2 20 A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415 V Type C 10 kA DIN Rail 100 → 133V 85mm 36mm 78.5mm -
RS Stock No. 776-3054
Mfr. Part No.A9N18361
PHP15,741.22
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2 80 A - Acti 9 C120N 440 V Type C 10 kA, 20 kA - ≤250V - - 81mm -
RS Stock No. 791-3228
Mfr. Part No.A9F53310
PHP4,475.88
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3 10 A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415 V Type B 10 kA DIN Rail 100 → 133V 85mm 54mm 78.5mm -
RS Stock No. 791-3398
Mfr. Part No.A9F54332
PHP4,962.20
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3 32 A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415 V Type C 10 kA DIN Rail 100 → 133V 85mm 54mm 78.5mm -
RS Stock No. 776-8863
Mfr. Part No.A9K24325
PHP1,571.68
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3 25 A - Acti 9 iK60N 400 V Type C 6000 A - - - 54mm - -
RS Stock No. 776-8968
Mfr. Part No.A9F74106
PHP295.51
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1 6 A - Acti 9 iC60N 230 V, 400 V Type C 6 kA - 72V - 18mm - -
RS Stock No. 776-3058
Mfr. Part No.A9N18362
PHP17,421.30
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2 100 A - Acti 9 C120N 440 V Type C 10 kA, 20 kA - ≤250V - - 81mm -
RS Stock No. 776-9015
Mfr. Part No.A9F74225
PHP1,329.80
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2 25 A - Acti 9 iC60N 440 V Type C 6 kA - 144V - 36mm - -
RS Stock No. 776-3430
Mfr. Part No.A9F74103
PHP2,987.98
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1 3 A - Acti 9 iC60N 240 V Type C 10 kA - 72V - - 85mm -
RS Stock No. 776-3436
Mfr. Part No.A9F74102
PHP2,986.41
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1 2 A - Acti 9 iC60N 240 V Type C 10 kA - 72V 18mm 78.5mm 85mm -
RS Stock No. 776-8826
Mfr. Part No.A9F84310
PHP2,142.46
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3 10 A - Acti 9 iC60H 440 V Type C 10 kA - 144V - 54mm - -
RS Stock No. 776-8829
Mfr. Part No.A9F84316
PHP2,142.46
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3 16 A - Acti 9 iC60H 440 V Type C 10 kA - 144V - 54mm - -
RS Stock No. 791-3427
Mfr. Part No.A9F54410
PHP7,336.52
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4 10 A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415 V Type C 10 kA DIN Rail 220 → 250V 85mm 72mm 78.5mm -
RS Stock No. 791-3338
Mfr. Part No.A9F54204
PHP4,116.49
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2 4 A - Acti 9 iC60H 440 V, 12 → 133 V, 220 → 240 V, 380 → 415 V Type C 10 kA DIN Rail 100 → 133V 85mm 36mm 78.5mm -