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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RS Stock No. 849-6525
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC1P50C
Brand :Europa
THB122.36
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1 50 A - EU EUC 230/400 V Type C 10 kA - - 18mm 78mm 87mm -
RS Stock No. 849-6550
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC2P20C
Brand :Europa
THB426.55
Each
Units
2 20 A - EU EUC 230/400 V Type C 10 kA - - 36mm 78mm 87mm -
RS Stock No. 849-6522
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC1P40C
Brand :Europa
THB229.41
Each
Units
1 40 A - EU EUC 230/400 V Type C 10 kA - - 18mm 78mm 87mm -
RS Stock No. 849-6591
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC3P32C
Brand :Europa
THB648.93
Each
Units
3 32 A - EU EUC 230/400 V Type C 10 kA - - 54mm 78mm 87mm -
RS Stock No. 849-6531
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC2P2C
Brand :Europa
THB426.55
Each
Units
2 2 A - EU EUC 230/400 V Type C 10 kA - - 36mm 78mm 87mm -
RS Stock No. 849-6597
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC3P25C
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THB721.14
Each
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3 25 A - EU EUC 230/400 V Type C 10 kA - - 54mm 78mm 87mm -
RS Stock No. 849-6572
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC3P1C
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THB663.37
Each
Units
3 1 A - EU EUC 230/400 V Type C 10 kA - - 54mm 78mm 87mm -
RS Stock No. 849-6496
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC1P2C
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THB196.03
Each
Units
1 2 A - EU EUC 230/400 V Type C 10 kA - - 18mm 78mm 87mm -
RS Stock No. 849-6553
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC2P25C
Brand :Europa
THB471.84
Each
Units
2 25 A - EU EUC 230/400 V Type C 10 kA - - 36mm 78mm 87mm -
RS Stock No. 849-6484
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC1P63B
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THB139.59
Each
Units
1 63 A - EU EUB 230/400 V Type B 10 kA - - 18mm 78mm 87mm -
RS Stock No. 849-6529
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC1P63C
Brand :Europa
THB211.18
Each
Units
1 63 A - EU EUC 230/400 V Type C 10 kA - - 18mm 78mm 87mm -
RS Stock No. 849-6563
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC2P63C
Brand :Europa
THB471.84
Each
Units
2 63 A - EU EUC 230/400 V Type C 10 kA - - 36mm 78mm 87mm -
RS Stock No. 849-6519
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC1P25C
Brand :Europa
THB229.41
Each
Units
1 25 A - EU EUC 230/400 V Type C 10 kA - - 18mm 78mm 87mm -
RS Stock No. 849-6581
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC3P10C
Brand :Europa
THB616.50
Each
Units
3 10 A - EU EUC 230/400 V Type C 10 kA - - 54mm 78mm 87mm -
RS Stock No. 849-6594
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC3P20C
Brand :Europa
THB648.93
Each
Units
3 20 A - EU EUC 230/400 V Type C 10 kA - - 54mm 78mm 87mm -
RS Stock No. 849-6538
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC2P1C
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THB434.20
Each
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2 1 A - EU EUC 230/400 V Type C 10 kA - - 36mm 78mm 87mm -
RS Stock No. 849-6575
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC3P2C
Brand :Europa
THB648.93
Each
Units
3 2 A - EU EUC 230/400 V Type C 10 kA - - 54mm 78mm 87mm -
RS Stock No. 849-6557
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC2P32C
Brand :Europa
THB524.40
Each
Units
2 32 A - EU EUC 230/400 V Type C 10 kA - - 36mm 78mm 87mm -
RS Stock No. 849-6490
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC1P4C
Brand :Europa
THB200.53
Each
Units
1 4 A - EU EUC 230/400 V Type C 10 kA - - 18mm 78mm 87mm -
RS Stock No. 849-6601
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.EUC3P40C
Brand :Europa
THB648.93
Each
Units
3 40 A - EU EUC 230/400 V Type C 10 kA - - 54mm 78mm 87mm -