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 Length Width Depth Application
RS-stocknr. 814-7481
Fabrikantnummer60150
€ 156,94
Each
Aantal stuks
2 35 A - - C60 Type C 120 → 240 V 125V 10 kA rms @ 125 V dc, 20 kA rms @ 240 V ac - 107mm 36mm 78.5mm -
RS-stocknr. 734-9248
FabrikantnummerA9F74602
€ 94,20
Each
Aantal stuks
1 + N 2 A - Acti 9 iC60N Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 230 V - 6 kA - - 36mm - -
RS-stocknr. 734-9226
FabrikantnummerA9F74201
€ 103,20
Each
Aantal stuks
2 1 A - Acti 9 iC60N Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - - - -
RS-stocknr. 791-3408
FabrikantnummerA9F54340
€ 76,19
Each
Aantal stuks
3 40 A - Acti 9 iC60H Type C 12 → 133 V, 220 → 240 V, 380 → 415 V, 440 V 100 → 133V 10 kA DIN Rail 85mm 54mm 78.5mm -
RS-stocknr. 734-9131
FabrikantnummerA9F74202
€ 103,20
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, 440 V 12 → 144V 6 kA - - 36mm - -
RS-stocknr. 734-9220
FabrikantnummerA9F74204
€ 103,20
Each
Aantal stuks
2 4 A - Acti 9 iC60N Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - - - -
RS-stocknr. 734-9664
FabrikantnummerA9F75216
€ 66,83
Each
Aantal stuks
2 16 A - Acti 9 iC60N Type D 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - 36mm - -
RS-stocknr. 734-9652
FabrikantnummerA9F75206
€ 81,66
Each
Aantal stuks
2 6 A - Acti 9 iC60N Type D 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - - - -
RS-stocknr. 734-9251
FabrikantnummerA9F74604
€ 94,20
Each
Aantal stuks
1 + N 4 A - Acti 9 iC60N Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 230 V - 6 kA - - 36mm - -
RS-stocknr. 814-7438
Fabrikantnummer60105
€ 32,50
Each
Aantal stuks
1 4 A - - C60 Type C 120 → 240 V 60V 10 kA rms @ 240 V ac, 10 kA rms @ 60 V dc - 107mm 18mm 78.5mm -
RS-stocknr. 734-9686
FabrikantnummerA9F75332
€ 121,80
Each
Aantal stuks
3 32 A - Acti 9 iC60N Type D 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - 54mm - -
RS-stocknr. 734-9692
FabrikantnummerA9F75463
€ 308,84
Each
Aantal stuks
4 63 A - Acti 9 iC60N Type D 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 250V 6 kA - - 72mm - -
RS-stocknr. 814-7532
Fabrikantnummer60127
€ 69,61
Each
Aantal stuks
1 10 A - - C60 Type D 120 → 240 V 60V 10 kA rms @ 240 V ac, 10 kA rms @ 60 V dc - 107mm 18mm 78.5mm -
RS-stocknr. 734-9661
FabrikantnummerA9F75210
€ 66,83
Each
Aantal stuks
2 10 A - Acti 9 iC60N Type D 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - - - -
RS-stocknr. 814-7526
Fabrikantnummer60122
€ 76,31
Each
Aantal stuks
1 4 A - - C60 Type D 120 → 240 V 60V 10 kA rms @ 240 V ac, 10 kA rms @ 60 V dc - 107mm 18mm 78.5mm -
RS-stocknr. 734-9318
FabrikantnummerA9F94220
€ 102,67
Each
Aantal stuks
2 20 A - Acti 9 iC60L Type C 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 10 kA - - - - -
RS-stocknr. 734-9674
FabrikantnummerA9F75310
€ 104,87
Each
Aantal stuks
3 10 A - Acti 9 iC60N Type D 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - - - -
RS-stocknr. 734-9734
FabrikantnummerA9F75325
€ 116,17
Each
Aantal stuks
3 25 A - Acti 9 iC60N Type D 12 → 60 V, 100 → 130 V, 220 → 240 V, 380 → 415 V, 400 V, 440 V 12 → 144V 6 kA - - - - -
RS-stocknr. 814-7469
Fabrikantnummer60143
€ 148,73
Each
Aantal stuks
2 8 A - - C60 Type C 120 → 240 V 125V 10 kA rms @ 125 V dc, 20 kA rms @ 240 V ac - 107mm 36mm 78.5mm -
RS-stocknr. 814-7508
Fabrikantnummer60179
€ 217,37
Each
Aantal stuks
3 15 A - - C60 Type C 120 → 240 V - 20 kA rms @ 240 V ac - 107mm 54mm 78.5mm -