ELECTRICITY - Safety FIRST


Electricity symbol


                     We have already discussed about the Shock less electricity in one of our previous post  (* recommended read this), following the shock less electricity in this blog we'll discuss about how the traditional components work & how to implement them!!

                          

Traditional components:

  •       FUSE
  •       MCB
  •       ELCB                     
Fuse


       Fuses are the very oldest – simplest productive device for our electrical and electronics equipment. Fuse will be placed at the starting of the circuit (Technically soon after the supply from mainboard, prior to all electrical equipment). 

The fuse is just the small metal "wire or strip" which melts when the current exceeds the rated value… by this concept, the circuit will become open circuit, soon the current stops to flow since the current flows only in a closed path/circuit.

 We must use a fuse in our home/factory etc..by including the fuse we can protect the faults like short circuits, over current, overloading, mismatched loads & device failures.

         !! Wait for a minute but the fuse can’t achieve shock-less electricity, yes the fuse has some problems/bugs in its operations.!!

HERE COMES OUR SUPER SAVER-MCB                                                      

Miniature circuit breaker


         MCB (Miniature circuit breaker) is one of the protective devices for our electrical/electronic equipment. The actual purpose of the MCB is to do the work as same as a fuse (basically all protective elements will first aim to disconnect the loads from the main supply). 

        You may ask "But why MCB,we already have a fuse!! for circuit protection. The reason is that as we discussed earlier about fuse which has some operating bugs, one of the major bugs is that once the fuse operator is melted totally we must need to replace it,that means a fuse will be used till it dies,after successfully melting for protecting our devices it can't be reused.

        To overcome this major issue MCB’s are introduced as a secondary protective layer. In MCB as well as Fuse the operating key is current, in fuse when the rated current is exceeded it will melt out totally but the MCB has a thermal mechanism & it will work based on heat – here the heat will be generated by the current. 

        The thermal mechanism will trigger the tripper inside the MCB then the system will become an open circuit and hence as a result the equipments are protected. Soon after the MCB is triggered off we can simply reset the MCB once after the electrical issue/fault is rectified and we can reuse the same MCB.

 

Drawbacks!

          We can't prevent shocks from electricity only with the use of these FUSE & MCBs,

Rectification to prevent leakage current:

         Sometimes there will be a leakage current in any part of the circuit.It has to be safely grounded..so that a person who touches the device won't be affected. Now the game-changer is introduced in the circuit breaker industry. That is named "ELCB".


Earth leakage circuit breaker (ELCB) :

Earth leakage circuit breaker

       It is also a safety device that is used to prevent electrical shock. It works based on the differential transformer. This key concept has been taken from the clamp amp meter. In the domestic electricity (Home) it contains two lines basically, one is phase and another is neutral (for single-phase supply). 

       The Phase is also called as live wire - current follows through phase and returns through neutral after its usage by the load, the amount of current in & out (magnitude of current in phase & neutral) is almost equal.

By this theory of the concept, it led to invert the ELCB. In most of the traditional safety devices (like a fuse, MCB, etc.) They sense the flow of current in either phase or in neutral (but mostly it will be in the phase for safety, as phase is the live conductor). But the ELCB senses (actually compares) the current in both phase and neutral. When the balance of current in phase & neutral fails the circuit breaker will trigger the circuit and the main circuit will be made open, by this way if there is any leakage current in either phase or neutral can be found (by comparing the incoming[phase] & outgoing[neutral] currents).

 The leakage can’t be taken much easier in electricity because it’s the main reason for shock in the human body. The leakage current will be flowing in the body of the device, when a person touches the device unknowingly he may get shock.

By using a differential transformer, the current is compared in the phase & neutral then if needed (fault occurs) it operates the trigger mechanism.

            As ELCB can’t protect the devices from overload and short circuit current the Fuse and MCB are must in domestic/industrial electrical connections. By the combo of traditional protective devices which include ELCB the electrical/electronic devices, as well as the human life, could be saved from leakage/over electricity at an affordable cost. 

 


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