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. 772-1476
Fabrikantnummer5SY6006-6
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€ 23,90
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1 + N 6 A - Sentron 5SY6 Type B 230 V - 6 kA - 90mm 18mm 77mm -
RS-stocknr. 772-1486
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RS-stocknr. 772-1482
Fabrikantnummer5SY6010-7
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€ 25,20
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1 + N 10 A - Sentron 5SY6 Type C 230 V - 6 kA - - 18mm 77mm -
RS-stocknr. 772-1470
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€ 54,50
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1 + N 6 A - Sentron 5SY6 Type C 230 V - 6 kA - - 18mm 77mm -
RS-stocknr. 383-2018
Fabrikantnummer5SY4106-7
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€ 26,50
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1 6 A - Sentron 5SY4 Type C 400 V - 10 kA - 89.8mm 17.6mm 76.4mm -
RS-stocknr. 772-1296
Fabrikantnummer5SY4206-7
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€ 63,50
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2 6 A - Sentron 5SY4 Type C 400 V - 10 kA - 90mm 36mm 76mm -
RS-stocknr. 521-4939
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€ 26,90
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1 2 A - Sentron 5SY6 Type C 230 V, 400 V - 6 kA - 89.8mm 17.6mm 76.4mm -
RS-stocknr. 772-1495
Fabrikantnummer5SY6016-7
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€ 25,20
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1 + N 16 A - Sentron 5SY6 Type C 230 V - 6 kA - 90mm 18mm 77mm -
RS-stocknr. 489-6704
Fabrikantnummer5SY6110-6
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€ 12,20
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1 10 A - Sentron 5SY6 Type B 230 V, 400 V - 6 kA - 89.8mm 17.6mm 76.4mm -
RS-stocknr. 521-4945
Fabrikantnummer5SY6103-7
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€ 26,90
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1 3 A - Sentron 5SY6 Type C 230 V, 400 V - 6 kA - 89.8mm 17.6mm 76.4mm -
RS-stocknr. 772-1432
Fabrikantnummer5SY4516-6
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€ 45,10
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1 + N 16 A - Sentron 5SY4 Type B 230 V - 10 kA - 90mm 36mm 76mm -
RS-stocknr. 772-1280
Fabrikantnummer5SY4204-7
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€ 69,30
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2 4 A - Sentron 5SY4 Type C 400 V - 10 kA - 90mm 36mm 76mm -
RS-stocknr. 489-6710
Fabrikantnummer5SY6316-7
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€ 90,90
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3 16 A - Sentron 5SY6 Type C 400 V - 6 kA - 89.8mm 52.8mm 76mm -
RS-stocknr. 489-6625
Fabrikantnummer5SY6106-7
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€ 24,60
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1 6 A - Sentron 5SY6 Type C 230 V, 400 V - 6 kA - 89.8mm 17.6mm 76.4mm -
RS-stocknr. 521-4951
Fabrikantnummer5SY6104-7
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€ 26,90
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1 4 A - Sentron 5SY6 Type C 230 V, 400 V - 6 kA - 89.8mm 17.6mm 76.4mm -
RS-stocknr. 772-1372
Fabrikantnummer5SY4310-7
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€ 100,00
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3 10 A - Sentron 5SY4 Type C 400 V - 10 kA - 89.8mm 52.8mm 76mm -
RS-stocknr. 772-1414
Fabrikantnummer5SY4506-7
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€ 50,20
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1 + N 6 A - Sentron 5SY4 Type C 230 V - 10 kA - 90mm 36mm 76mm -
RS-stocknr. 622-0036
Fabrikantnummer5SY4104-7
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€ 27,00
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1 4 A - Sentron 5SY4 Type C 230 V, 400 V - 10 kA - 89.8mm 17.6mm 76.4mm -
RS-stocknr. 383-2125
Fabrikantnummer5SY4316-7
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€ 93,60
Each
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3 16 A - Sentron 5SY4 Type C 400 V - 10 kA - 89.8mm 52.8mm 76mm -
RS-stocknr. 124-3151
Fabrikantnummer5SY4101-8
FabrikantSiemens
€ 38,40
Each
Aantal stuks
1 1 A - Sentron 5SY4 Type D 230 V, 400 V - 10 kA - 17.6mm 76.4mm 89.8mm Industrial, Plant Engineering