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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Omschrijving Prijs Number of Poles Current Rating Model Number Range Series Tripping Characteristics Rated AC Voltage Rated DC Voltage Breaking Capacity Mounting Style Breaking Capacity at Maximum Voltage Rating Length Width Depth
RS-stocknr. 746-7706
Fabrikantnummer2CDS252001R0064 S202-C6
FabrikantABB
€ 60,55
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Aantal stuks
2 6 A - System M Pro S200 Type C 400V - - - 6 kA 88mm 35mm 69mm
RS-stocknr. 539-8346
Fabrikantnummer2CDS213001R0104 SH203-C10
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€ 56,64
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3 10 A - System M Pro S200 Type C 440V - - - 6 kA 85mm 52.5mm 69mm
RS-stocknr. 539-8352
Fabrikantnummer2CDS213001R0164 SH203-C16
FabrikantABB
€ 58,07
Each
Aantal stuks
3 16 A - System M Pro S200 Type C 440V - - - 6 kA 85mm 52.5mm 69mm
RS-stocknr. 734-9248
FabrikantnummerA9F74602
€ 89,49
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- 2 A - Acti 9 iC60N Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 230V - - - 6 kA - 36mm -
RS-stocknr. 734-9226
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€ 98,04
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2 1 A - Acti 9 iC60N Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440V 12 → 144V - - 6 kA - - -
RS-stocknr. 791-3408
FabrikantnummerA9F54340
€ 95,95
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3 40 A - Acti 9 iC60H Type C 12 → 133 V, 220 → 240 V, 380 → 415V, 440 V 100 → 133V - DIN Rail 10 kA 85mm 54mm 78.5mm
RS-stocknr. 514-0125
Fabrikantnummer2CDS251001R0377 S201-K6
FabrikantABB
€ 30,39
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1 6 A - System M Pro S200 Type K 253V 72V - - 6 kA 88mm 17.5mm 75.8mm
RS-stocknr. 746-7699
Fabrikantnummer2CDS252001R0024 S202-C2
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€ 60,55
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2 2 A - System M Pro S200 Type C 400V - - - 6 kA - 35mm 69mm
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Fabrikantnummer239158 & FAZ6-B16/3N
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€ 129,25
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- 16 A - XEffect FAZ6 Type B 230 → 400V - - - 6 kA 80mm 17.5mm 61.5mm
RS-stocknr. 734-9131
FabrikantnummerA9F74202
€ 98,04
Each
Aantal stuks
2 2 A - Acti 9 iC60N Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440V 12 → 144V - - 6 kA - 36mm -
RS-stocknr. 535-4251
Fabrikantnummer2CDS273001R0064 S203M-C6
FabrikantABB
€ 107,80
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Aantal stuks
3 6 A - System M Pro S200 Type C 440V - - - 10 kA - - 75.8mm
RS-stocknr. 734-9220
FabrikantnummerA9F74204
€ 98,04
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2 4 A - Acti 9 iC60N Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415V, 400 V, 440 V 12 → 144V - - 6 kA - - -
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€ 68,89
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2 16 A - Acti 9 iC60N Type D 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440V 12 → 144V - - 6 kA - 36mm -
RS-stocknr. 922-7099
Fabrikantnummer278674 & FAZ-C16/1N
FabrikantEaton
€ 45,22
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RS-stocknr. 539-8330
Fabrikantnummer2CDS213001R0064 SH203-C6
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3 6 A - System M Pro S200 Type C 440V - - - 6 kA 85mm 52.5mm 69mm
RS-stocknr. 131-927
Fabrikantnummer2CDS272001R0255 S202M-B25
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€ 61,88
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2 25 A - System M Pro S200 Type B 440V 125V - - 10 kA 88mm 35mm 75.8mm
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Fabrikantnummer2CDS272001R0104 S202M-C10
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2 10 A - System M Pro S200 Type C 440V 125V - - 10 kA 88mm 35mm 75.8mm
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€ 84,16
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Fabrikantnummer278869 & FAZ-C10/3
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€ 90,62
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Aantal stuks
3 10 A - XEffect FAZ Type C 400V - - - 10 kA 80mm 52.5mm 73.5mm