Differences b/w Power Supplies

Replies

• 

  narayana murthy

  as per my knowledge what happens is a 11kv is generated and it is generated to 440kv and stepped down to 132k then 11k then 220
  to overcome transmission losses i think you are asking about this if not post your question clearly
• 

  ABCD ABCD

  NO, i know abt transmission losses. My question was commercial which operate at 220V are lighted using 11kV. Why is this like that?
  I guess it's all to do with maximum current that can be drawn. See my 1st post clearly.
• 

  narayana murthy

  mreccentric

  NO, i know abt transmission losses. My question was commercial which operate at 220V are lighted using 11kV. Why is this like that?
  I guess it's all to do with maximum current that can be drawn. See my 1st post clearly.

  oh k then but i think in commercial use they are at high ratings
• 

  ABCD ABCD

  narayana murthy

  oh k then but i think in commercial use they are at high ratings

  may be that's the reason, but i'm not sure. On what factor does max current from power supply depend?
• 

  Emanresu

  Think of it as power demand and not power supply. Max amount of power.
  
  You may get a comprehensive answer.
  
  
• 

  maraitamilan

  Dont just think of lighting in commercial side theres high rated machines which have high losses for that 220V is not enough so they are swithcing on to 11kv
• 

  praba230890

  We are giving 11KV for commercial and industrial purposes to avoid the overload problem. It is similar to the reason why we are giving 3 phase to some homes instead of 1 phase supply.
  

  mreccentric

  Electricity Board supplies electricity, here as 220V and 11kV. The later is again decreased to 220V and then used. My question is what is the need for 11kV supply. I know that they are used in commercial complexes and industries, but why not just 220V?
  (I'm talking about only 2-phase).
  Another question: What is the maximum current that i can draw from these supplies? On what does it depend?

• 

  ratmo

  It is a nice sharing..........
• 

  RRITESH

  Another question: What is the maximum current that i can draw from these supplies? On what does it depend?

  Hi,
  
  you want to know maximum current drawn from transmission lines or supply depend on the rating of transformer.....
  
  for e.g.:- if you have 50VA transformer of 12V then the maximum current load can drive will be: P=VI acc. to this 50/12= 4amp (near by)
  
  it is the maximum current i f you connect a small light motor across it like 500mA, then it will drawn 500mA only not 4amp, it depend on the load how much it will take current. according to ohms law..!!!
• 

  ABCD ABCD

  RRITESH

  Hi,
  
  you want to know maximum current drawn from transmission lines or supply depend on the rating of transformer.....
  
  for e.g.:- if you have 50VA transformer of 12V then the maximum current load can drive will be: P=VI acc. to this 50/12= 4amp (near by)
  
  it is the maximum current i f you connect a small light motor across it like 500mA, then it will drawn 500mA only not 4amp, it depend on the load how much it will take current. according to ohms law..!!!

  "o/p of a transformers", thanks - that must be the answer.
• 

  d_vipul

  Hey Cean,
  
  The Voltage level is depend upon the power required..........
  Like For a 50kW machine to drive, if we use 11kV the current required to meet this loading is less where as if we use 220V then this required current is much much more......
  
  Reasons:
  
  1. To carry this high current at 220V we need larger diameter conductor which then creates problem while jointing and all......Instead if we use 11kV the conductor size decreases.........
  2. Losses at high voltage is low.......
  3. Low copper required for high voltage transmission and distribution........
  4. Higher Efficiency at 11kV than at 220V.............
  
  Hope this answer satisfies your requirement.........
  If Not then feel free to ask here..........
  
  Regards,
  Vipul
• 

  RRITESH

  Hello,
  
  If you have a load of 50W of 12V rating, then it does not mean that for equally power you will give any voltage & current to it......., in this 50W if you will try to give it 150V with few milli amps the load can be destroy permanently
  this is small e.g.: it depend on the rating of voltage also not only power!!
  
  a fan is voltage controlled device it will work without current limiting resistance, but in case of LED is a current limiting device supply directly without resistance the led will burn out.!!
• 

  PraveenKumar Purushothaman

  In simple terms, power is the capacity to drive the electrical component and the voltage is the potential required to drive it... 😀
• 

  d_vipul

  hey for 50W loads are available in both voltage ratings 12V as well as 50 V as well as in 150 Volts........
  but according to application supply rating you are supposed to use it...........
  
  But is kept in mind the same..........
  thats why I gave example of 50 kW machine.......which is an Industrial load.............
• 

  RRITESH

  I have a exhaust fan which run in 220V say it power is 400W, that doesn't mean i can give it more supply voltage then it maximum...like 350V it will sure burn out after few sec....
• 

  Chandrakiran

  Power and Voltage are inter related,
  I will ask a question, consider i have to deliver 500MW power through transmission lines and i have option to choose 400kV and 220kV what is the difference between the two? For 220kV lines to transmit the same power more lines are required compared to 400kV else line losses will be very high.
  Similarly, for commercial establishments and industries feeder from 132/11kV substation is directly taken because load requirement is very high in such cases. In industries below 160kW motors can be operated using 415V supply, but power rating more than 160kW requires 6.6kV supply to operate. If low voltage is given motor will not start and damages the windings of the motor. For particular power, it to be remembered that providing low voltage not only increases the line losses but also damages the load connected.
  Hence what i say is the voltage required for the load depends on the power rating of the load. I hope it helps..
• 

  RRITESH

  I will ask a question, consider i have to deliver 500MW power through transmission lines and i have option to choose 400kV and 220kV what is the difference between the two? For 220kV lines to transmit the same power more lines are required compared to 400kV else line losses will be very high.

  Hello,
  
  The question was different & your answer is pretty different, because transmission of power through line from one place to another station is different any voltage is chosen ( as P=v^2/r or P= I^2*R ) we use high voltage.............
  but if you have a load e.g; an home appliance will run only at its rating of volatge you can't drive a tube light at KV.......!!
• 

  Chandrakiran

  Electricity Board supplies electricity, here as 220V and 11kV. The later is again decreased to 220V and then used. My question is what is the need for 11kV supply. I know that they are used in commercial complexes and industries, but why not just 220V?
  
  @RRITESH:You did not read completely what i was presented. I was just answering the first post of the thread not other. iam not asking to connect the tube light to 220kV. I just quoted as an example how power and voltages are inter related as example.Coming to question it asks about why we are using different voltages (220 and 11kV) why don't we use 220V instead. I just explained that voltage rating of the electrical equipment depends on the power it is rated. If low voltage is provided it not only increases the line losses but also damages the machine.
• 

  RRITESH

  Ok........
• 

  PraveenKumar Purushothaman

  @Chandrakiran, great explanation!!! 😀
• 

  saketsingh

  Well if we are using the 11kv then the rating of the current will be less which will reduce our copper losses and safes the winding of the machines.
  Using 220v for the same power rating machine will incresase the current and thus losses including heat will increase.
• 

  praba230890

  Yeah you may be right saketsingh......but if that is considered for transmission. Here we are talking about distribution of power. Here the load is the deciding factor. If we wouldn't supply 11kv to commercial or industrial's and if we consider supplying them from a normal distribution transformer that supplies an area. Then due to high energy requirement there will be overloading of transformers and will bust out the supply to that whole area.
  

  saketsingh

  Well if we are using the 11kv then the rating of the current will be less which will reduce our copper losses and safes the winding of the machines.
  Using 220v for the same power rating machine will incresase the current and thus losses including heat will increase.