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

...
อ่านเพิ่มเติม อ่านน้อยกว่า

คัดกรอง / Filters

กำลังดูสินค้า 1 - 20 รายการจาก 71 รายการ / Viewing 1 - 20 of 71 products
ผลการค้นหาต่อหน้า / Results Per Page
รายละเอียดสินค้า / Description ราคา / Price Number of Poles Current Rating Model Number Range Series Rated AC Voltage Tripping Characteristics Breaking Capacity Mounting Style Rated DC Voltage Length Width Depth Application
RS Stock No. 731-9730
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 078 34
Brand :Legrand
THB7,984.91
Each
Units
3 50 A - DX Range DX3 230 V, 400 V Type C 10 kA - - - - - -
RS Stock No. 731-9718
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 078 27
Brand :Legrand
THB3,480.64
Each
Units
3 10 A - DX Range DX3 230 V, 400 V Type C 10 kA - - - - - -
RS Stock No. 823-4668
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 067 83
Brand :Legrand
THB858.37
Each
Units
1 16 A - DX Range DNX3 250 V Type C 4.5 kA - 12V 77.7mm - 94.8mm -
RS Stock No. 731-9689
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 077 02
Brand :Legrand
THB2,455.17
Each
Units
1 + N 25 A - DX Range DX3 230 V Type C 10 kA - - - - - -
RS Stock No. 823-4683
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 068 83
Brand :Legrand
THB827.24
Each
Units
1 16 A - DX Range DX3 250 V Type C 4.5 kA - 12V 77.7mm - 94.8mm -
RS Stock No. 731-9755
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 078 99
Brand :Legrand
THB4,660.84
Each
Units
4 20 A - DX Range DX3 230 V, 400 V Type C 10 kA - - - - - -
RS Stock No. 731-9780
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 062 58
Brand :Legrand
THB1,105.12
Each
Units
- 6 A - - DX3 250 V - - - - - - - -
RS Stock No. 731-9777
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 093 62
Brand :Legrand
THB17,931.03
Each
Units
4 80 A - DX Range DX3 - Type C 16 kA - - - - - -
RS Stock No. 731-9679
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 076 92
Brand :Legrand
THB2,947.76
Each
Units
1 + N 1 A - DX Range DX3 230 V Type C 10 kA - - - - - -
RS Stock No. 731-9566
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 077 15
Brand :Legrand
THB2,221.24
Each
Units
1 + N 20 A - DX Range DX3 230 V Type C 10 kA - - - - - -
RS Stock No. 731-9682
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 076 94
Brand :Legrand
THB2,858.03
Each
Units
1 + N 3 A - DX Range DX3 230 V Type C 10 kA - - - - - -
RS Stock No. 731-9685
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 076 95
Brand :Legrand
THB2,858.03
Each
Units
1 + N 4 A - DX Range DX3 230 V Type C 10 kA - - - - - -
RS Stock No. 620-2971
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.0 225 15
Brand :Legrand
THB5,696.84
Each
Units
4 63 A - - Vistop 400 V - 15 kA - - 90mm 125mm 104mm -
RS Stock No. 823-4674
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 068 81
Brand :Legrand
THB827.24
Each
Units
1 10 A - DX Range DX3 250 V Type C 4.5 kA - 12V - 17.8mm 94.8mm -
RS Stock No. 731-9461
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 077 14
Brand :Legrand
THB2,061.46
Each
Units
1 + N 16 A - DX Range DX3 230 V Type C 10 kA - - - - - -
RS Stock No. 731-9443
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 067 73
Brand :Legrand
THB771.80
Each
Units
1 + N 10 A - DX Range DNX3 - Type C 4.5 kA - - - - - -
RS Stock No. 293-1417
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.0 058 11
Brand :Legrand
THB381.80
Each
Units
1 16 A - - - - - - - - - - - -
RS Stock No. 731-9449
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 067 71
Brand :Legrand
THB1,130.30
Each
Units
1 + N 2 A - DX Range DNX3 - Type C 4.5 kA - - - - - -
RS Stock No. 731-9705
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 077 78
Brand :Legrand
THB3,629.42
Each
Units
2 3 A - DX Range DX3 230 V, 400 V Type C 10 kA - - - - - -
RS Stock No. 731-9483
หมายเลขชิ้นส่วนของผู้ผลิต / Mfr. Part No.4 077 82
Brand :Legrand
THB2,161.26
Each
Units
2 10 A - DX Range DX3 230 V, 400 V Type C 10 kA - - - - - -