Miniature Circuit Breaker
MCB (Miniature Circuit Breaker ( BS 3871 ) is a mechanical device operate automatic operation designed to connect and disconnect the electrical circuit in the ordinary and extraordinary situation.Suitable for AC and DC voltage.It mean main function is to protected equipment or circuit from overload and short circuit.
The size of MCB is small and usually use for household appliance and domestic.Average fix ampere rating from 6 Amp up to 125 Amp. It can be reset back to the normal condition after trip but cannot adjusted ampere rating.It can be found for single phase 1ø and three phase 3ø voltage power supply.
Basic construction
- A switching mechanism
- An automated operation device
- Arc extinguisher
- Have a fixed contact and moving contact
- Comply with IEC 60898
- Breaking capacity not less than 6 kA ( RMS )
- The tripping element
MCB Type,Instant trip and Application table
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1 2.7 – 4 In Domestic and commercial
B 3 – 5 In
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2 4 – 7 In
C 5 – 10 In General use,small motor
3 7 – 10 In
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D 10 – 20 In High in rush equipment
4 10 – 50 In
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K Frequent short duration
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Z Semiconductor devices
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Description of MCB ( Miniature circuit breaker )
Detail of MCB
1) Actuator piker ( for trip and reset )
2) Actuator Device mechanism
3) Main contact ( flow of current )
4) Terminal Block
5) Bimetallic steel strip
6) Tripping calibration screw
7) Solenoid coil
8) Arc extinguisher
How many pole for Miniature circuit breaker?
There are four designs in the market for MCB
1) One (1) pole
For single phase use ( Live )
2) Two (2) pole
For single phase use ( Live & Neutral )
3) Three (3) pole
For three phase use ( R,S,T ) or TP ( three pole )
4) Four (4) pole
For three phase use ( R,S,T,Neutral) or TPN ( three pole & neutral )
I already discuss in my post about how to sizing the circuit breaker :D feel free to visit :D
Dear sir,
This is Mr. Vemula Balaiah
I am Graduate Electrical Engineer
Please clarify the below Doubts.
How we can select the MCB Rating?
it depends on load? if yes please clarify the below ratings.
Data is : 3-Phase, 50HZ , 415V .
1. if Load is 1000 Watts then what is the MCB Rating?
2. if load is 1500 Watts then What is the MCB Rating?
3. if Load is 2500 Watts then what is the MCB Rating?
4. if Load is 2000 Watts then what is the MCB Rating?
5. If Load is 640 Whats then what is the MCB Rating?
plz revert to me as early as possible.
i am waiting for your early kind response.
Thanking you sir,
Thanks and regards,
Mr.Vemula Balaiah
HYDERABAD, A.P.,. INDIA
Dear mr vemula balaiah
how to set MCB rating…
rating for MCB depend on AMPERE
so,first u must confirm the FULL LOAD AMPERE for your load then u can set the MCB rating.. or u can use this formula for get your ampere I = P / ( I x V x 1.732 )
second,u must know what type for your MCB depend on your application..i already expalin detail about type off MCB
please refer my post…
thanks for your question…
sorry for the late reply :D
Im using 6 drives with 0.5 hp,i want to know the MCB rating for each VFD
Dear Siva,
I already explain in my last post
http://www.electricneutron.com/circuit-breaker/miniature-circuit-breaker-sizing/
i hope it can answer ur question
Sir,
We are using capictors for power factor improvement.Please suggest us the
Rating of MCB for 15Kvar,20Kvar capacitors,.also give us the methode for the calculation of MCB Rating..
dear mahesh kulkarni..for the simple calculation for mcb sizing,please refer the FULL LOAD AMPERE for your capacitor,and multiply with 0.25 for safety factor.u can get the rated ampere for your mcb. Example : the full load ampere is 25 ampere,multiply with 0.25 and you get 31.25 ampere…so from the mcb ampere rated from manufacture,you can use mcb 32 ampere rated current…refer to my post about mcb sizing
dear sir,
A machine 380v,60hz,its full load amps is 244.
which amps mcb we can use this circuit.pls reply as soon as possible to my mail id.
Dear kunhimon,maximum MCB rated ampere only until 125 ampere.So..from your data,the full load machine is 244 ampere..you cannot use the MCB…
I suggest you to use the MCCB ( molded case circuit breaker ) because it have bigger ampere range,from 15 amp until 2000 amp.
For this machine i suggest you to use 300 ampere of MCCB.
DEAR SIR,
i WANT TO KNOW HOW TO SELECT MCB FOR DIFFERENT RATINGS MOTOR PLS GIVE ME FORMULA FOR THIS.
THANK YOU…
hi bhargav,please read my last post about how to sizing mcb.i explain detail about it.thanks
MCB DEPAIND ON FLA
SO
FLA*1.5
yes..true…it depend on full load ampere and our application
sir i need connection diagram of star delta stator motor
I will attach the control diagram of star delta starter for ur reference.
timer connection of star delta startor
sir i don’t know how to connect timer in star delta stator
up to how much kw motor can we use DOL starter?
Dear anil nair
please refer to my last post about motor starter…
http://www.electricneutron.com/motor-control/motor-starter-method/
thanks
I have two (2) generators of 5.6KW,112v D.C/ 8KVA 220 A.C generator and One (1) generator of 7.5KVA for a complex which has total equipment load of 30 Amps. Can you please suggest where all should I put MCB and of what all rating.
The set up is like
8KVA GenNo 1 + 8KVA Gen No 2—- CHANGEOVER 1
8 KVA Gen No 1 + 7.5 KVA Gen —— CHANGEOVER 2 —CHANGEOVER No2 —CHANGEOVER NO3.
MAIN and Output of Changeover 2 goes to Changeover 3.
and output of changeover 3 goes to Distribution box. and from distribution box the output goes to various rooms and equipment rooms. can you please suggest broadly where all MCB should be put and of what rating
Dear sir
i want “forward revers” star delta starter connection diagram if use with four contactor only this starter useing from up& down lifting machine
witch side is load side, mean where i connect load at top side or bottom side.
Normal practice :
Top side : incoming power supply
Bottom side : outgoing to load
dear sir
If dc current flowing in 6 amp.AC mcb how much take current to trip 6 amp.ac mcb