What is a miniature circuit breaker or MCB


Miniature circuit breaker or MCB is an electrical protection device which cuts off electric circuit from power source during short circuit. During short circuit the circuit draws abnormally high current which can cause fire or other damage. To avoid such damage it is a must to isolate the shorted circuit from the rest of the power system or the power source. A miniature circuit breaker acts like an automatic fuse. In older days fuse was used in electrical system to protect the circuit. Whereas in today's modern installations circuit breakers are used in place of fuse. Fuse has the same function but it could not be switched on back after tripping once it broke. It requires to replace the whole burned fuse or to rewire it in case of re-wire-able fuse. Whereas in case of miniature circuit breaker, it could be reset after short circuit repair like a switch. The reset time is way too less for a miniature circuit breaker compared to a fuse repair or replacement. MCB or miniature circuit breaker is frequently used in latest installations and wiring. Some people think that miniature circuit breaker or MCB is more sensitive than a fuse. But this is not the reality. In reality the fuse is way too sensitive then miniature circuit breaker or mcb and a fuse works in almost all conditions. But in some special cases like in elcb or earth leakage circuit breaker. In case of earth leakage circuit breaker it provides a special feature of protection which a fuse can't provide. The research says that it needs half a cycle time of ac wave form to blow a fuse whereas a miniature circuit breaker needs one complete cycle or even more to trip it and to isolate the circuit. Anyway miniature circuit breaker is still the best choice of protection.


How MCB or miniature circuit breaker works

There are two types of trip arrangements in MCB or miniature circuit breaker. First is bimetallic temperature trip and second is electromagnetic trip. If high current or over current flows through bimetallic strip, it bends due to over temperature. A mechanical latching mechanism is attached to the bimetallic strip. The bend of bimetallic strip releases the latch. The mechanical latch is further attached to the tripping mechanism of the circuit breaker. The release of the latch cases to trip the circuit breaker and opens the contact and isolate the circuit attach to it. The other way is opening the contacts by electromagnetic force. When high current flows through the mcb, the electromagnet inside the mcb becomes stronger and attracting the plunger inside. The plunger is attached to the latch. the attraction of the plunger releases the latch and in this way the tripping mechanism of the circuit breaker is activated to the circuit breaker tirps and isolates the defective circuit from the power source.

MCB is designed to use and is not repaired if it is going defective. Normally they are thrown and replaced when they become defective. The replacement of the mcb is easy and it takes less time to replace. There are two types of protections inside an mcb. It provides protection against short circuit as well as against overloading. The electromagnet part provides protection against short circuit and the bimetallic part provides protection against overloading.

Comments

Post a Comment

Popular posts from this blog

Microwave oven front panel keypad repair and modification

Image
Here is the video on youtube. You must watch it if you are a Urdu to Hindi viewer: Here is the video on youtube. You must watch it if you are an English viewer: The microwave oven is a useful machine to preheat or cook food. The microwave oven is working reliably but now a days Chinese microwave oven have big front panel keypad failure. The keypad is breaking down in one year of less time. The repair is not easy and sometimes the replacement parts are not readily available then it becomes another problem. The solution to such a problem is a modification with existing easily available parts and some wire connections to the main board. The modification is a very robust an reliable work so that will never break down or if breaks down, the repair would be way easy and low cost. Here is a little detail with images is included for such a modification work. Most of the images are from the video associated with this blog post. Anyhow it will further explain the important
Read more

Sandwich maker or sandwich grill repair and maintenance

Image
Here is a youtube video covering all these details in video: Sandwich maker or sandwich grill is a common house hold electrical appliance used in every house and every facility. They are daily use electrical appliances. They are of different make and model. One thing is common in all of them is the heating element and a sort of temperature controlling switch operated on some preset or selectable temperature range. The heating element are heated by line power and are switched off when the desired temperature is reached. By that way the grill or heating plate is heated and the toast put there is also grilled or heated by that temperature. Sandwich makers or sandwich grill are reliable equipment but some times they develop troubles. The result is no heating grill or heating plates. Normally there are electrical connection problem or temperature controlling switch problem. The heating element failure is also possible but that is a rare fault. So if a grill or sandwich
Read more

How to check SMD or surface mount resistances value from their code and test on multimeter

Image
Test smd resistor using a multimeter Digit code for smd resistors Here is the video on this topic you can watch for further details: Surface mount resistors or SMD resistors are very commonly used in electrical and electronics circuits. They are found everywhere in all electronics equipment today. They have certain value in resistance or Ohms which is mentioned on them in the form of a digital code. Here the following image is showing a surface mounted resistors circuit where you can see the SMD resistors and the rest of soldering on the PCB. Her in this image you can see the surface mounted or SMD resistances with a digital code on them. The resistors have a specific value code on them. This code is easy to learn and off course easy to print on the small and tiny body of an SMD resistor. This code consists of three digits or three value alfa numeric code is also used. Sometimes this could be a four digit code also in case of very high precision resistors. We will only dis
Read more