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 Prix Number of Poles Current Rating Model Number Range Series Tripping Characteristics Rated AC Voltage Rated DC Voltage Breaking Capacity Mounting Style Length Width Depth Application
N° de stock RS 776-6707
Référence fabricantA9N21557
35,65 €
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1 + N 16 A - Acti 9 iDPN Type C 230 V - 10 kA - - 70mm 80mm -
N° de stock RS 734-9131
Référence fabricantA9F74202
98,04 €
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2 2 A - Acti 9 iC60N Type C 100 → 130 V, 12 → 60 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - 36mm - -
N° de stock RS 776-2698
Référence fabricantA9N21555
38,00 €
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1 + N 6 A - Acti 9 iDPN Type C 230 V - 10 kA - 18mm - 80mm -
N° de stock RS 776-2685
Référence fabricantA9N21553
41,70 €
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1 + N 2 A - Acti 9 iDPN Type C 230 V - 10 kA - - 70mm 80mm -
N° de stock RS 776-2691
Référence fabricantA9N21556
38,00 €
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1 + N 10 A - Acti 9 iDPN Type C 230 V - 10 kA - 18mm - 80mm -
N° de stock RS 734-9220
Référence fabricantA9F74204
98,04 €
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2 4 A - Acti 9 iC60N Type C 400 V, 440 V, 100 → 130 V, 12 → 60 V, 220 → 240 V, 380 → 415 V 12 → 144V 6 kA - - - - -
N° de stock RS 776-6732
Référence fabricantA9N21600
144,00 €
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3 + N 32 A - Acti 9 iDPN Type C 400 V - 10 kA - - - 80mm -
N° de stock RS 776-6726
Référence fabricantA9N21597
121,50 €
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3 + N 16 A - Acti 9 iDPN Type C 400 V - 10 kA - - 70mm 80mm -
N° de stock RS 734-9264
Référence fabricantA9F74203
98,04 €
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2 3 A - Acti 9 iC60N Type C 400 V, 440 V, 100 → 130 V, 12 → 60 V, 220 → 240 V, 380 → 415 V 12 → 144V 6 kA - - 36mm - -
N° de stock RS 776-6741
Référence fabricantA9N21601
172,00 €
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3 + N 40 A - Acti 9 iDPN Type C 400 V - 10 kA - 54mm 70mm 80mm -
N° de stock RS 776-6700
Référence fabricantA9N21558
39,45 €
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1 + N 20 A - Acti 9 iDPN Type C 230 V - 10 kA - 18mm 70mm 80mm -
N° de stock RS 734-9661
Référence fabricantA9F75210
68,89 €
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2 10 A - Acti 9 iC60N Type D 400 V, 440 V, 100 → 130 V, 12 → 60 V, 220 → 240 V, 380 → 415 V 12 → 144V 6 kA - - - - -
N° de stock RS 776-2689
Référence fabricantA9N21554
51,43 €
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1 + N 3 A - Acti 9 iDPN Type C 230 V - 10 kA - - 70mm 80mm -
N° de stock RS 776-6738
Référence fabricantA9N21599
134,00 €
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3 + N 25 A - Acti 9 iDPN Type C 400 V - 10 kA - - 70mm 80mm -
N° de stock RS 776-2682
Référence fabricantA9N21552
51,43 €
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1 + N 1 A - Acti 9 iDPN Type C 230 V - 10 kA - 18mm - 80mm -
N° de stock RS 776-6735
Référence fabricantA9N21598
91,07 €
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3 + N 20 A - Acti 9 iDPN Type C 400 V - 10 kA - - 70mm 80mm -
N° de stock RS 734-9664
Référence fabricantA9F75216
68,89 €
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2 16 A - Acti 9 iC60N Type D 100 → 130 V, 12 → 60 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - 36mm - -
N° de stock RS 734-9652
Référence fabricantA9F75206
84,16 €
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2 6 A - Acti 9 iC60N Type D 100 → 130 V, 12 → 60 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - - - -
N° de stock RS 776-6729
Référence fabricantA9N21596
127,50 €
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Unité
3 + N 10 A - Acti 9 iDPN Type C 400 V - 10 kA - - 70mm 80mm -
N° de stock RS 734-9686
Référence fabricantA9F75332
118,73 €
Each
Unité
3 32 A - Acti 9 iC60N Type D 100 → 130 V, 12 → 60 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - 54mm - -