The Electrical Engr.

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ARCING at the circuit breaker contacts | Reasons, Risks and Remedy

- July 16, 2019

Arcing at Circuit Breaker Contacts Reasons•Risk•Remedy Arcing is a phenomenon commonly seen whenever a circuit breaker is operated. This video describes the reason of arcing, why it is dangerous and how to stop it. Watch here

If two coils are wound on a wooden core insulated from each other, will there be mutual inductance between them?

- June 14, 2019

Yes for small power like RF application, wooden core is used. Wood has permeability almost equal to that of air. Most of the RF applications require air core winding which removes the complexity of non-linear behavior of a magnetic core having low reluctance. That's why such a core can't be pushed into saturation and the reluctance strictly depends on mean core length (lg) and area of cross section (Ag) given by the relation Reluctance, R=lg/µAg Where µ is the permeability. Permeability simply means the ease with which magnetic flux can pass through a material. As seen, Reluctance increases with decreasing µ and vice versa, hence the reluctance called as magnetic resistance. For higher power application it is not suitable but windings which require air core can use woods (and are used to provide strength and rigidness to the windings). Here µ can be called permeability of air which is 4π×10^(-7). A good material used for core in power applications is Silicon Steels or e...

Why an SCR/Thyristor can't be turned OFF?

- May 31, 2019

An SCR or thyristor is a semi-controlled power electronic switch. Semicontrolled means you can turn it on but can't turn it off. An SCR in simple meaning is a latched NPN and PNP transistor model. Once the trigger given, both the transistor helps to drive each other and in this way the conduction through an SCR sustains. I simulated an SCR and explained what is latching and why SCR can't be turned off by switching the gate potential off. This simulation might give you a clear idea what's happening exactly in an SCR without going much in design details. For more such informative videos on Electrical and Electronics Engineering, Subscribe to my channel on Youtube by the button given below.