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

...
Read more Read less

Filters

Viewing 2581 - 2600 of 2951 products
Results per page
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 Stock No. 849-6566
Mfr. Part No.EUC2P40C
BrandEuropa
HK$138.77
Each
units
2 40 A - EU EUC 230/400V Type C - - 10 kA 36mm 78mm 87mm -
RS Stock No. 188-1657
Mfr. Part No.P1MBUH3PC10
BrandLovato
HK$992.19
Each
units
3 - - - - - - DIN Rail Mount - - 54mm 75.52mm 116mm -
RS Stock No. 293-1401
Mfr. Part No.0 058 10
BrandLegrand
HK$115.45
Each
units
1 10 A - - - - - - - - - - - -
RS Stock No. 124-3174
Mfr. Part No.5SY4263-8
BrandSiemens
HK$1,289.55
Each
units
2 63 A - Sentron 5SY4 400V Type D - - 10 kA 35.2mm 76mm 89.8mm -
RS Stock No. 191-6100
Mfr. Part No.A9P22740
HK$2,032.20
Each
units
- 40 A A9P22740 Acti 9 Acti9iDT40T - Type C DIN Rail - 6 kA 18mm 78mm 81mm -
RS Stock No. 532-5045
Mfr. Part No.278609 & FAZ-S4/1
BrandEaton
HK$191.96
Each
units
1 4 A - XEffect FAZ 230V Type S - - 10 kA 80mm 17.5mm 73.5mm -
RS Stock No. 539-8302
Mfr. Part No.2CDS213001R0205
BrandABB
HK$414.71
Each
units
3 20 A - System M Pro S200 440V Type B - - 6 kA 85mm 52.5mm 69mm -
RS Stock No. 191-6086
Mfr. Part No.A9P22604
HK$449.25
Each
units
- 4 A A9P22604 Acti 9 Acti9iDT40T - Type C DIN Rail - 6 kA 18mm 78mm 81mm -
RS Stock No. 124-3044
Mfr. Part No.EMCH310 & EMCH310
BrandEaton
HK$661.24
Each
units
3 10 A - MEMShield EMCH 230 V, 240V Type C - 48V 10 kA 54mm 75mm 80mm Instantaneous
RS Stock No. 746-8015
Mfr. Part No.S202-K40
BrandABB
HK$689.85
Each
units
2 40 A - System M Pro S200 400V Type K - - 6 kA 88mm 35mm 69mm -
RS Stock No. 772-1509
Mfr. Part No.A9N61508
HK$740.57
Each
units
1 10 A - Acti 9 C60H-DC - Type C - 250V - - 18mm 73mm -
RS Stock No. 922-7144
Mfr. Part No.279061 & FAZ-C16/4
BrandEaton
HK$1,196.65
Each
units
4 16 A - XEffect FAZ 240 → 415V Type C - 96V 10 kA 70.8mm 65.5mm 80mm Instantaneous
New
RS Stock No. 210-3382
Mfr. Part No.5SL4516-6
BrandSiemens
HK$329.03
Each
units
5 16 A 5SL4516 SENTRON 5SL4 - - - - - - - - -
RS Stock No. 791-3313
Mfr. Part No.A9F54140
HK$265.34
Each
units
1 40 A - Acti 9 iC60H 12 → 60 V, 100 → 133 V, 220 → 240V Type C DIN Rail 12 → 48V, 72 V 10 kA 85mm 18mm 78.5mm -
RS Stock No. 769-4545
Mfr. Part No.239060 & FAZ6-C10/1N
BrandEaton
HK$333.21
Each
units
- 10 A - XEffect FAZ6 230 → 400V Type C - - 6 kA 80mm 17.5mm 61.5mm -
RS Stock No. 776-3222
Mfr. Part No.A9N61539
HK$1,328.28
Each
units
2 63 A - Acti 9 C60H-DC - Type C - 500V 20 kA - - 81mm -
RS Stock No. 435-273
Mfr. Part No.2CCS892001R0801
BrandABB
HK$1,626.35
Each
units
2 80 A - High Performance S800 400 V, 690V Type D - - 36 kA - - 88.5mm -
RS Stock No. 847-3526
Mfr. Part No.278896 & FAZ-D16/3
BrandEaton
HK$609.37
Each
units
3 16 A - XEffect FAZ 240 → 415V Type D - - 10 kA 54mm 84.7mm 72.6mm -
RS Stock No. 183-3619
Mfr. Part No.352225
BrandABB
HK$767.41
Each
units
2 500 mA S202 - S202 440V Type C DIN Rail 125V 10 kA 35mm 69mm 88mm -
RS Stock No. 124-3195
Mfr. Part No.5SY4410-8
BrandSiemens
HK$1,139.89
Each
units
4 10 A - Sentron 5SY4 400V Type D - - 10 kA 70.4mm 76mm 89.8mm -
Related Products
From RS Pro a high quality and durable ...
Description:
From RS Pro a high quality and durable power cable assembly or power cord for connecting an appliance to a mains power supply. This power cord is fully equipped with a UK BS1363 3 pin mains plug on one end ...
RS Pro power cord in black colour, has ...
Description:
RS Pro power cord in black colour, has C13 x2 connector A on one end and UK Plug connector B on the other end. It is current rated for 10 A, 3/5/10/13 A and voltage rated for 250 V. This ...
From APC, this 10 A C13 to C14 ...
Description:
From APC, this 10 A C13 to C14 jumper cable has fully moulded connectors with integral strain relief. With a 2.5m long cable, power cable assembly is ideal as an extension for C13/C14 connectors, and is commonly used in office ...
Brought to you under the trusted RS Brand, ...
Description:
Brought to you under the trusted RS Brand, this Schucko plug to C13 connector power cord has a coiled lead for convenience in storage and connection. This Schuko power cord is able to be used in many European countries, and ...