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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Description Price Number of Poles Current Rating Model Number Range Series Rated AC Voltage Tripping Characteristics Mounting Style Rated DC Voltage Breaking Capacity at Maximum Voltage Rating Length Width Depth Break Time
RS庫存編號 131-955
製造零件編號2CDS272001R0324 S202M-C32
BrandABB
TWD1,658.00
單位
2 32 A - System M Pro S200 440V Type C - 125V 10 kA 88mm 35mm 75.8mm -
RS庫存編號 746-7986
製造零件編號2CDS252001R0377 S202-K6
BrandABB
TWD2,382.00
單位
2 6 A - System M Pro S200 400V Type K - - 6 kA 88mm 35mm 69mm -
RS庫存編號 746-7659
製造零件編號2CDS251001R0084 S201-C8
BrandABB
TWD573.00
單位
1 8 A - System M Pro S200 230V Type C - - 6 kA 88mm 17.5mm 69mm -
RS庫存編號 539-8144
製造零件編號2CDS211001R0105 SH201-B10
BrandABB
TWD470.00
單位
1 10 A - System M Pro S200 440V Type B - 60V 6 kA 85mm 17.5mm 69mm -
RS庫存編號 746-7762
製造零件編號2CDS253001R0134 S203-C13
BrandABB
TWD2,167.00
單位
3 13 A - System M Pro S200 400V Type C - - 6 kA 88mm 52.5mm 69mm -
RS庫存編號 132-059
製造零件編號2CDS272001R0325 S202M-B32
BrandABB
TWD1,462.00
單位
2 32 A - System M Pro S200 440V Type B - 125V 10 kA 88mm 35mm 75.8mm -
RS庫存編號 539-8188
製造零件編號2CDS211001R0325 SH201-B32
BrandABB
TWD470.00
單位
1 32 A - System M Pro S200 440V Type B - 60V 6 kA 85mm 17.5mm 69mm -
RS庫存編號 514-0080
製造零件編號2CDS251001R0217 S201-K1
BrandABB
TWD978.00
單位
1 1 A - System M Pro S200 253V Type K - 72V 6 kA - 17.5mm 75.8mm -
RS庫存編號 746-8078
製造零件編號2CDS254001R0607 S204-K63
BrandABB
TWD7,852.00
單位
4 63 A - System M Pro S200 400V Type K - - 6 kA - - 69mm -
RS庫存編號 746-7573
製造零件編號2CDS252001R0255 S202-B25
BrandABB
TWD1,362.00
單位
2 25 A - System M Pro S200 400V Type B - - 6 kA 88mm 35mm 69mm -
全新
RS庫存編號 212-1627
製造零件編號2CDS252280R0165
BrandABB
TWD1,408.00
單位
2P 16 A S202C-B16 Compact S200C - Type B - - - - - - -
RS庫存編號 746-8012
製造零件編號2CDS252001R0607 S202-K63
BrandABB
TWD2,993.00
單位
2 63 A - System M Pro S200 400V Type K - - 6 kA 88mm - 69mm -
RS庫存編號 535-4166
製造零件編號2CDS271001R0204 S201M-C20
BrandABB
TWD641.00
單位
1 20 A - System M Pro S200 253V Type C - 72V 10 kA 88mm 17.5mm 75.8mm -
RS庫存編號 192-0891
製造零件編號66806
BrandABB
TWD11,783.00
單位
- - - - - - - - - - - - - -
全新
RS庫存編號 212-1638
製造零件編號2CDS253280R0025
BrandABB
TWD2,231.00
單位
3P 2 A S203C-B2 Compact S200C - Type B - - - - - - -
全新
RS庫存編號 212-1628
製造零件編號2CDS252280R0204
BrandABB
TWD1,408.00
單位
2P 20 A S202C-C20 Compact S200C - Type C - - - - - - -
RS庫存編號 746-8043
製造零件編號2CDS253001R0607 S203-K63
BrandABB
TWD4,672.00
單位
3 63 A - System M Pro S200 400V Type K - - 6 kA - 52.5mm 69mm -
RS庫存編號 535-4172
製造零件編號2CDS271001R0254 S201M-C25
BrandABB
TWD641.00
單位
1 25 A - System M Pro S200 253V Type C - 72V 10 kA 88mm 17.5mm 75.8mm -
全新
RS庫存編號 212-1629
製造零件編號2CDS252280R0205
BrandABB
TWD1,408.00
單位
2P 20 A S202C-B20 Compact S200C - Type B - - - - - - -
RS庫存編號 535-6049
製造零件編號2CDS271001R0505 S201M-B50
BrandABB
TWD735.00
單位
1 50 A - System M Pro S200 253V Type B - 72V 10 kA 88mm 17.5mm 75.8mm -