Now, we will study the function of different fuses and miniature circuit breakers (M.C.B.’s) used to protect the appliances/circuits from over-current flow. Due to this over current flow the wires and switches starts overheating and finally catch fire. The current drawn by appliances or a circuit from the main supply depends upon its internal resistance. Under normal working conditions, the current drawn by the appliance will be within the safe limit. So the temperature of the connecting wires and switches, will remain within safe limit. Suppose the appliance or circuit starts drawing more current, due to occurrence of any kinds of fault, the heat generation in the wires and switches, starts increasing. As the temperature goes on increasing, the insulation between the wires starts melting and the circuit resistance reduces to very low and further increase in current drawn. So, the higher currents will start flowing in the connecting wires and switches, which will results in set fire to wires and even to building also. So, we have to make some arrangement to limit this current by providing a week (Thin) point in the circuit. This week point should break the connection, by melting/fusing itself, when the circuit current exceeds the safe limit. This device is known as fuse. The materials, used in fuse wire, are tin,lead, zinc silver, antimony, copper, aluminium etc. Copper or lead tin alloy is mostly used in ordinary rewirable fuses.
We know that once the fuse is blown, we need to rewire it, which is a time consuming job and requires lot of safety precautions. To replace a blown fuse especially in marriages and parties becomes critical, as it requires lot of time and skill. So, keeping in view, different problems associated with fuse, another safety device is now a day is being used, known as “Miniature Circuit Breaker” A Miniature Circuit Breaker (MCB) is today’s version of old fuses. Today in most of the homes, factories, plants and offices miniature circuit breakers are installed replacing the earlier rewirable or cartridge fuses. The miniature circuit breakers(MCB) are more safe, convenient and reliable than the old fuses. If the circuit or appliance starts drawing more than the rated current due to overloading or occurrence of any other faults, the MCB will get tripped and hence supply circuit is switched off immediately. After removing the fault, we can restore the power supply just switch on the MCB. It is so easy and safe, like putting on the light switch on that even a child can operate it.
We know that once the fuse is blown, we need to rewire it, which is a time consuming job and requires lot of safety precautions. To replace a blown fuse especially in marriages and parties becomes critical, as it requires lot of time and skill. So, keeping in view, different problems associated with fuse, another safety device is now a day is being used, known as “Miniature Circuit Breaker” A Miniature Circuit Breaker (MCB) is today’s version of old fuses. Today in most of the homes, factories, plants and offices miniature circuit breakers are installed replacing the earlier rewirable or cartridge fuses. The miniature circuit breakers(MCB) are more safe, convenient and reliable than the old fuses. If the circuit or appliance starts drawing more than the rated current due to overloading or occurrence of any other faults, the MCB will get tripped and hence supply circuit is switched off immediately. After removing the fault, we can restore the power supply just switch on the MCB. It is so easy and safe, like putting on the light switch on that even a child can operate it.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.