What is the  Differences between AC and DC Current 

 

            Hi friends Today, I explain the difference between AC & DC current, I will explain 22 differences,difference between ac and dc current

       

  1) AC means alternative current, if it is voltage, then also, it is called AC voltage.

             DC means direct current

         2)  AC reverse direction periodically, DC flows only in 1 direction.

         3)  Magnitude of current vary with time in AC,like this

how ac current works

alternating current graph explained

             In the case of DC, current value may be constant, this is magnitude, this is time scale, value is     fixed, like this

what is dc power

Every where equal, so it is called constant or DC value may vary with time, value is changing with time, But, current direction remains same. DC was pure at the time of invention, this type came later, this is called DC with ripple.

          4)  The frequency of AC is 50 Hz or 60 Hz ,The one cycle of AC show in figure below

 50 Hz means, 50 cycles like this in 1 secs. 60 cycles in a sec means 60 Hz, frequency is country based, it is 50 Hz in India.

               Pure DC means zero frequency, this has zero frequency, but there may be ripple                        also,

          Voltage may be pure DC in Laptop, mobiles etc, but current load will not be pure DC, current may be different, Many IC and transistor in the circuits, will go on becoming ON and OFF, so DC current value will be changing, 

        

            5)  In past wireless Radio, Tv transmission uses high frequency AC In Analog, But                           Now days analog is very less, 

               Now days mostly digital transmission is use, DC pulses are used in DC, Pulse will 

               come like ON, OFF, ON, OFF, DC pulses will come in sequence.

            

             6) AC is mostly sinusoidal, like this, in plus and minus both, small signal may be trapezoidal, like this, small AC signal may be triangular like this, or square like this, signal is in plus & minus both in all these, 

               All these wave pes wshaill be in DC also, but value will be only in plus or minus, these signals are also called pulsating DC, DC wave in figure. 

 

     7) AC equation is written like this, V=20 Sin(omega)t .this 20 is peak value, not RMS 

                  value.

                 Voltage is fixed in DC, Equation for pure DC, will be V=20 (example), If DC has 

                 some portion of AC ripple also, then we write like this V=20 + 5 Sin(omega)t, 

     8) AC can be generated mechanically such as a generator,

                 DC also cam be generated using generator with some ripple and also with battery.

      

    9)  A rectifier is required to convert AC into DC, but inverter is required to convert DC                      into  AC.

  10) AC is not portable, it can be generated by using portable generator,

                  DC can be carries around in form of battery.so ,it is use in portable electronics like                                  mobiles,meters,radios,laptop etc.

          

  11) Electricity is supplied to consumer in AC form, not in DC form.

  12)  It is easier to protect AC current,because, zero crossing will come in AC after                           some time, there, it may be zero volt or zero current, so current will reduce, after 

                    some time in case of fault, 

                 But it does not happens in DC, it is difficult to protect DC current, DC MCB may be                             expensive, 

  13) Rating of AC fused gets reduced in DC circuit, if fuse is rated for 230 volt AC,                            then same fuse may work, up to 40 or 50 volt in DC circuit.

  14) AC Is not store,if AC power fail then use another AC Source or use DC with 

                    Inverter.

                     DC is stored direct in DC form.

  15) AC voltage can be changed easily using transformer, It is difficult to change 

                     voltage in DC, we require complex power circuit, to change DC voltage, that will 

                     be expensive also.

  16) AC is used in loads like motors,light,heating etc in industry and houses.

                      DC is used in low power and low voltage electronics devices.one more use of 

                      DC ,In chemical industry 50000 amp D  current s require,there is 50000 amp 

                       rectifier is use. 

                      it's call HCR ( high current rectifier)

  17) In AC ,2 power generating station, with different frequency, are difficult to 

                       connect in parallel, but paralleling is must, because, if one station fails, then     

                       other station can be used, so both are synchronized.

                               A DC link is connected between 2 generating stations, 1st AC is      

                       converted into DC, then DC is converted into AC, so 2 generating stations of     

                      different frequencies, can be inter connected, this is called HVDC, also called 

                      back to back HVDC link.

  18)AC POWER can't be transmitted for vary long  distance due to stability 

                         problem,

                        Power in DC form, can be transmitted for long distance, using HVDC, high 

                        voltage DC transmission.

  19)  AC transmission is economical for less distance, DC transmission is 

                          economical for long distance.

  20)  AC transmission is efficient for less distance, DC transmission is efficient for 

                           long distance, 

  21) Storage of DC power is possible in Battery, Controllability of DC is also 

                           better, So DC can be used, for high power also many places, 1st AC is       

                           converted into DC, then DC is converted again into AC, 

                   Some example are VFD, HVDC, UPS, and also control system supply in Industry, 

                  

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