Recently added

When to use I²R, V²/R or VI while calculating Electric Power?

-
Image
I came across a question that was asked to me quite a couple of time: When to use I²R, V²/R or VI while calculating power? At first, the question looks simple and as if it needs no formal explanation but that's not the case. Use of any of them will give the correct result provided that you apply it correctly. Correct application is possible only when you understand the type of circuit you are dealing with. Another important point is to use the one which is going to take less time and help you calculate easily. All of the three equations tell the same thing but their usage is subject to the type of problem you're trying to solve. Let us understand when, how an what to use while calculating power in an electrical circuit.
Post a Comment

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

-
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 even better CRGO steel. CRGO steels have low reluctance in the path of flow of flux and comparatively high in the other directions. CRGO steels are used as cores to power transformers.

P.S. You can compare magnetic flux to electric current and reluctance to impedance. The current always follows the path of least impedance. Similarly the flux choses path if minimum reluctance (the voltage source can be compared to MMF if you want to know which is equal to product of Amperes and turns). So, we can increase the mmf by increasing number of turns which would give us required flux as Reluctance is a constant quantity. Moreover, the required inductance also increases as the square of number of turns as it is given by

L=µ(N^2)A/l

A being area of cross section and l being length of the coil (length of coil means length of the winding not the conductor).

Subscribe to my Youtube channel to get informative videos on Electrical and Electronics Engineering. 
 

Comments

Post a Comment

Popular posts from this blog

Why earth pin in a 3 pin plug made thicker and longer than other 2?

-
Image
We have been using various electrical appliances in our household having such socket plugs as shown above. The upper pin is called an earth pin while the lower two are live and Neutral. But have you ever wondered why the earth pin looks so different than the other two pins? If you had, here's the answer. An earth pin is used to discharge any electric current flowing through the metallic enclosure of an electric appliance due to some internal fault or loose connection to the earth. The current flowing through the metallic enclosure is taken up by an earth wire in the appliance and is sent to earth through the earth pin in the socket.  Now in no way, the earth pin should be inserted in live or neutral hole on the socket because in that case, current would flow through the earth pin to the appliance and also will result in burn-out as well as insulation breakdown. That's why, the earth pin is made thick or different in dimension than the other two pins so that
Read more

CONVERT AC TO DC using transistors cheaply and Easily | RECTIFIER

-
Image
 Happy New Year everybody out there and sorry for the late update. So, This video describes how to make a full bridge rectifier SIMPLY and CHEAPLY at home using basic transistors. Must watch. I hope you will like this video. Please share this video if you have liked and do subscribe to my channel. This encourages me to bring more such informative videos on Electrical Engineering in future for you. Thanks.
Read more

Working & Application of a Variable Voltage Variable Frequency Drive (VVVfD)

-
Image
Variable Voltage Variable Frequency Drive (VVVfD) is one of the best and efficient methods of starting an Induction Motor Drive as well as it provides a smooth and wide range of Torque-Speed control. It saves electrical power and provides good motor starting and running characterstics. VVVfD controls the V/f (Volt/Hz) fraction to let the motor drive achieve good Torque-Speed characterstics as required. Hence it is also called, VSD - Variable Speed Drive or AFD - Adjustable Frequency Drive or Inverter based Drive as it uses Inverter to achieve the set points.  But how VVVfD works and why it is better than various other methods of Starting and Speed Control of Induction Motor based applications. Let's discuss the Theory, Working, Advantages and Applications of a VVVfD in detail.          
Read more